Slab-on-Grade
Remake batch 22: rewritten from scratch under the authoring cheatsheet with datasheet constraints; scope boundaries restated against the remade neighbors
Showing changes from Rev 3
to Rev 4
in Slab-on-Grade.
---
title: Slab-on-Grade
category: Structural / Concrete
−toc_depth: 3
description: >
− When to use: cast-in-place slab-on-grade construction for commercial, industrial,
− warehouse, institutional, and retail buildings — unreinforced, conventionally
− reinforced, post-tensioned, or fiber-reinforced slabs bearing directly on compacted
− subgrade or subbase. Covers the full assembly: subgrade preparation and compaction,
− granular subbase, vapor retarder placement, mix design, thickness, reinforcement or
− fiber dosage, joint layout, curing, and flatness/levelness tolerances for interior
− floors, exterior aprons, dock pads, equipment pads, and utility slabs.
− Not intended for: structural mix proportioning, formwork, and placement of elevated
− or formed concrete (sync/cast-in-place-concrete); rebar schedules, splices, and bar
− placement tolerances (sync/concrete-reinforcement); vapor retarder material selection,
− perm ratings, and seaming (sync/vapor-retarders); decorative grinding, densifiers,
− and sealers (sync/polished-concrete); concrete pavements designed for AASHTO vehicular
− loading; and structural mat foundations or PT transfer slabs that resist column loads.
+ When to use: Concrete slabs on ground that serve as building floors on commercial, institutional, industrial, warehouse, and pre-engineered metal building projects, bearing directly on a prepared subgrade or on a granular subbase rather than on a structural frame. Covers the decisions that make a floor slab a designed element rather than a poured surface: the design basis the Engineer of Record records (subgrade modulus, design loads, thickness), the granular subbase and its surface, the condition of the supporting surface when concrete is placed, whether a vapor retarder is provided beneath the slab and the sequence it fixes, the crack-control strategy (plain, welded wire reinforcement, deformed bars, steel or synthetic macrofibers, shrinkage-compensating concrete, or post-tensioning) and the form, position, and support of reinforcement within the slab, thickened edges that act as integral grade beams, contraction, isolation, and construction joint layout, load transfer across joints, joint filling, floor flatness and levelness by F-numbers, the pre-placement verification, and acceptance of the finished floor.
+
+ Not intended for: The concrete itself, its mixture classes, strength, drying shrinkage limit, delivery, placement, consolidation, weather protection, and strength acceptance (see [[sync/cast-in-place-concrete]]); reinforcing steel products, grades, bending, splices, cover, and corrosion protection (see [[sync/concrete-reinforcement]]); edge forms, bulkheads, and release agents (see [[sync/concrete-formwork]]); curing methods and duration, surface finishing, and surface-defect acceptance (see [[sync/concrete-curing-and-finishing]]); the vapor retarder product, its ASTM E1745 class and permeance, laps, seams, penetration sealing, and repair (see [[sync/vapor-barriers-under-slab]]); bar supports, chairs, and the embedded plates and anchor rods cast into the slab (see [[sync/concrete-accessories]]); preformed compressible filler materials and waterstops (see [[sync/concrete-joints-and-waterstops]]); excavation, fill, compaction, proof rolling, and acceptance of the subgrade (see [[sync/earthwork]]); the material, lift placement, and compaction of a dense-graded aggregate base used as the subbase (see [[sync/aggregate-base-course]]); spread and strip footings and the foundation walls the slab abuts (see [[sync/shallow-foundations]]); prestressing strand, anchorages, sheathing, and stressing of a post-tensioned slab (see [[sync/post-tensioned-concrete]]); grinding, densifying, and polishing of the hardened surface (see [[sync/polished-concrete]]); moisture testing of the slab before a floor covering is installed and topical moisture mitigation, which belong to the standard for the covering (see [[sync/resilient-flooring]], [[sync/wood-flooring]], [[sync/carpet]], and [[sync/resinous-flooring]]); exterior pavements, aprons, sidewalks, and curbs (see [[sync/concrete-paving]]); equipment pads and housekeeping pads (see [[sync/concrete-pads]]); elevated slabs, structural mats, and transfer slabs that span to a frame or resist column loads; and assessment and repair of hardened or deteriorated concrete (see [[sync/concrete-repair-and-restoration]]).
---
# Scope {toc}
−## This standard covers cast-in-place concrete slabs supported by and in direct contact with the ground, where the soil and any subbase carry the slab loads rather than a structural frame. {note}
+## This standard covers concrete slabs on ground that serve as building floors: the design basis recorded for them, the subbase and the supporting surface beneath them, the vapor retarder decision and the sequence it fixes, the crack-control strategy and the reinforcement or fibers within the slab, thickened edges, joint layout and load transfer, joint filling, flatness and levelness, the pre-placement verification, and acceptance of the finished floor. {note}
−## A slab-on-grade (SOG) is a ground-supported floor: the subgrade, not beams or columns, provides the reaction to applied loads. This distinguishes it from a structurally supported slab, where the design and detailing are fundamentally different. Because the slab and the ground act as a system, the quality of the finished floor depends as much on subgrade preparation and joint layout as on the concrete itself. {note}
+## A slab on ground is supported continuously by the soil beneath it, and that single fact separates it from every other concrete element in the building. It does not span, so its thickness is set by wheel and post loads against the stiffness of the subgrade rather than by bending between supports. It shrinks against the friction of the ground it sits on, so it cracks unless the cracks are given somewhere to form. And it is the one element whose top surface is the finished product: the flatness a lift truck feels, the joint edge a pallet jack strikes, and the moisture a flooring adhesive sees are all properties of the slab itself. The decisions this standard records are the ones that determine whether those properties are designed or accidental. {note}
−## The slab assembly addressed here includes the prepared subgrade, granular subbase, vapor retarder, reinforcement or fiber, concrete, joints, curing, and surface tolerances as a coordinated whole. {note}
+## The structural design of the slab, its thickness, its reinforcement, its joint spacing, and the loads it carries, is performed by the Engineer of Record under ACI 360R and recorded on the contract documents. This standard records the design basis the Engineer of Record selected, states how the slab is built to that design, and states how the finished floor is verified; it does not produce the design, and no value in it substitutes for a project-specific analysis. {note}
−## This standard applies to interior building floors, exterior aprons, dock and equipment pads, and utility slabs where the slab bears on the ground. {note}
+## The work of the following standards applies to slabs on ground and is not restated here. {note}
−## The following are outside this standard and are governed elsewhere. {note}
+- The concrete: mixture classes, specified strength, the drying shrinkage limit, delivery, placement, consolidation, hot- and cold-weather protection, field testing, and strength acceptance, under [[sync/cast-in-place-concrete]]
+- Reinforcing steel products, grades, bending, splices, cover, and corrosion protection, under [[sync/concrete-reinforcement]]
+- Bar supports and chairs, and the embedded plates and anchor rods cast into the slab, under [[sync/concrete-accessories]]
+- Edge forms, bulkheads, blockouts, and release agents, under [[sync/concrete-formwork]]
+- Curing methods and duration, surface finishing, evaporation retarder, and surface-defect acceptance, under [[sync/concrete-curing-and-finishing]]
+- The vapor retarder product, its ASTM E1745 class and permeance, its position, laps, seams, penetration sealing, repair, and protection before the pour, under [[sync/vapor-barriers-under-slab]]
+- Preformed compressible filler materials and waterstops, under [[sync/concrete-joints-and-waterstops]]
+- Excavation, fill, compaction, proof rolling, and acceptance of the subgrade, under [[sync/earthwork]]
+- The material, lift placement, and compaction of a dense-graded aggregate base, under [[sync/aggregate-base-course]]
+- Spread and strip footings and the foundation walls the slab abuts, under [[sync/shallow-foundations]]
+- Prestressing strand, anchorages, sheathing, stressing, and stressing records of a post-tensioned slab, under [[sync/post-tensioned-concrete]]
+- Equipment pads and housekeeping pads cast on the slab, under [[sync/concrete-pads]]
+- Grinding, densifying, and polishing of the hardened surface, under [[sync/polished-concrete]]
+- Assessment and repair of cracks and defects in the hardened slab, under [[sync/concrete-repair-and-restoration]]
−- Structural mix proportioning, formwork, and placement for elevated and formed concrete — see [[sync/cast-in-place-concrete]].
−- Reinforcing bar schedules, lap splices, hooks, and bar placement tolerances — see [[sync/concrete-reinforcement]].
−- Vapor retarder material classification, permeance, and seaming requirements — see [[sync/vapor-retarders]].
−- Decorative grinding, densifiers, stains, and sealer systems on finished surfaces — see [[sync/polished-concrete]].
−- Concrete pavements and roadways designed for vehicular traffic under AASHTO methods.
−- Structural mat foundations and post-tensioned transfer slabs that resist column loads.
+## Moisture testing of the slab before a floor covering is installed, and any topical moisture mitigation applied to the hardened surface, are specified by the standard for the covering: [[sync/resilient-flooring]], [[sync/wood-flooring]], [[sync/carpet]], and [[sync/resinous-flooring]] each state the test method, the limit, and the mitigation they require. This standard governs the conditions that let the slab dry from one face only: the vapor retarder beneath it and the sequence of its placement. {note}
−## Slab classification {toc}
+## Exterior pavements, aprons, sidewalks, and curbs are governed by [[sync/concrete-paving]]; elevated slabs, structural mats, and transfer slabs that span to a frame or resist column loads are governed by [[sync/cast-in-place-concrete]] and the structural drawings. {note}
−### The slab classification shall be selected to match the structural demand and crack-control strategy of the application.
+## Slabs on ground shall comply with [[sync/cast-in-place-concrete]] except as modified by this standard.
−```datasheet
−label: Slab classification
−type: radio
−options:
− - Plain (unreinforced) — crack control by joint spacing only
− - Conventionally reinforced — WWR or rebar for temperature/shrinkage
− - Steel fiber-reinforced
− - Synthetic macro-fiber reinforced
− - Post-tensioned (unbonded tendons)
−default: Conventionally reinforced — WWR or rebar for temperature/shrinkage
−```
+## Where this standard and a standard it references conflict, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
−### Classification drives nearly every downstream decision — thickness, reinforcement, joint spacing, and tolerance. Selecting it first prevents the common error of specifying a reinforcement type that is incompatible with the chosen joint strategy (for example, leaving wide-spaced joints in a plain slab carrying forklift loads). {note}
+## The Contractor shall not reduce the slab thickness, the reinforcement, the subbase thickness, or the dowel size shown on the contract documents, and shall not widen the joint spacing shown, without the written approval of the Engineer of Record.
−### Plain slabs rely entirely on closely spaced contraction joints to control random cracking and are appropriate only for lightly and uniformly loaded floors. {note}
−
−### Conventionally reinforced slabs carry welded wire reinforcement or a light rebar grid sized for temperature and shrinkage, not to prevent cracking but to hold crack widths tight between joints. {note}
−
−### Steel and synthetic macro-fiber slabs distribute reinforcement three-dimensionally through the section, providing post-crack toughness and allowing wider joint spacing than plain slabs. {note}
−
−### Post-tensioned slabs on grade use unbonded tendons with edge beams to precompress the slab, controlling cracking over expansive soils and across large jointless areas. {note}
−
# Referenced Standards {toc}
−## Materials, design, and construction shall comply with the latest adopted edition of each of the following unless a specific edition is cited.
+## Materials, design, construction, and testing shall comply with the latest adopted edition of each of the following unless a specific edition is cited.
−## Where referenced standards conflict, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
+## Where the contract documents, the adopted building code, or a referenced standard conflict, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
| Standard | Title |
|----------|-------|
−| ACI 360R-10 | Guide to Design of Slabs-on-Ground |
−| ACI 302.1R-15 | Guide to Concrete Floor and Slab Construction |
−| ACI 224.3R-95 | Joints in Concrete Construction |
−| ACI 117-10 | Specification for Tolerances for Concrete Construction and Materials |
−| ASTM E1745 | Plastic Water Vapor Retarders Used in Contact with Soil or Granular Fill under Concrete Slabs |
−| ASTM E1643 | Selection, Design, Installation, and Inspection of Water Vapor Retarders under Concrete Slabs |
−| ASTM E1155 | Determining FF Floor Flatness and FL Floor Levelness Numbers |
+| ACI 117 | Specification for Tolerances for Concrete Construction and Materials |
+| ACI 223R | Guide for the Use of Shrinkage-Compensating Concrete |
+| ACI 224.3R | Joints in Concrete Construction |
+| ACI 301 | Specifications for Concrete Construction |
+| ACI 302.1R | Guide to Concrete Floor and Slab Construction |
+| ACI 302.2R | Guide for Concrete Slabs that Receive Moisture-Sensitive Flooring Materials |
+| ACI 318 | Building Code Requirements for Structural Concrete and Commentary |
+| ACI 360R | Guide to Design of Slabs-on-Ground |
+| ACI 544.4R | Guide to Design with Fiber-Reinforced Concrete |
+| ASTM A36/A36M | Carbon Structural Steel |
+| ASTM A615/A615M | Deformed and Plain Carbon-Steel Bars for Concrete Reinforcement |
+| ASTM A820/A820M | Steel Fibers for Fiber-Reinforced Concrete |
+| ASTM A1064/A1064M | Carbon-Steel Wire and Welded Wire Reinforcement, Plain and Deformed, for Concrete |
| ASTM C920 | Elastomeric Joint Sealants |
−| ASTM D1751 | Preformed Expansion Joint Filler (Nonextruding and Resilient Bituminous Types) |
−| ASTM C33 | Concrete Aggregates |
−| ASTM C309 | Liquid Membrane-Forming Compounds for Curing Concrete |
−| ASTM C1315 | Liquid Membrane-Forming Compounds Having Special Properties for Curing and Sealing Concrete |
−| ASTM A1064 | Steel Wire and Welded Wire Reinforcement for Concrete |
−| ASTM D698 | Laboratory Compaction Characteristics of Soil (Standard Proctor) |
−| ASTM D1557 | Laboratory Compaction Characteristics of Soil (Modified Proctor) |
−| ASTM D6938 | In-Place Density and Water Content of Soil by Nuclear Methods |
−| IBC 2024 §1907 | Concrete Slabs-on-Ground |
−| IRC 2024 §R506 | Concrete Floors (On Ground) |
−| PTI DC80.3 | Design of Post-Tensioned Slabs-on-Ground |
+| ASTM C1116/C1116M | Fiber-Reinforced Concrete |
+| ASTM C1609/C1609M | Flexural Performance of Fiber-Reinforced Concrete (Using Beam With Third-Point Loading) |
+| ASTM D2240 | Rubber Property, Durometer Hardness |
+| ASTM D7508/D7508M | Polyolefin Chopped Strands for Use in Concrete |
+| ASTM E1155 | Determining FF Floor Flatness and FL Floor Levelness Numbers |
+| ICC IBC | International Building Code (Chapter 19, Concrete) |
+| PTI DC10.5 | Standard Requirements for Design and Analysis of Shallow Post-Tensioned Concrete Foundations on Expansive Soils |
+| PTI M10.2 | Specification for Unbonded Single Strand Tendons |
# Submittals {toc}
## Action Submittals {toc}
−### The Contractor shall submit the following action items for review before placing concrete:
+### The Contractor shall submit the following for review and acceptance before the subbase is placed beneath the first slab and before any slab concrete is placed:
−- Concrete mix design(s) with compressive strength, w/cm ratio, aggregate gradation, cement type, and supplementary cementitious material proportions.
−- Reinforcement shop drawings or fiber dosage data, including fiber type, length, and aspect ratio.
−- Joint layout drawing showing contraction, isolation, and construction joints with dimensions and saw-cut timing.
−- Vapor retarder product data with ASTM E1745 class, thickness, and permeance.
−- Curing method and product data, including ASTM C309 or C1315 classification.
−- Manufacturer data for dowels, joint filler, and sealant.
+- Slab placement and joint layout plan, drawn over the floor plan, showing the sequence and limits of each placement, construction joint locations, contraction joint lines and spacing, isolation joints at columns, walls, footings, pads, pits, and penetrations, the joints that receive load-transfer devices, the strike-off method and placement widths, and the sawing method and target timing
+- Reinforcement placing drawings for the slab, showing the welded wire reinforcement sheet designation and lap, or the bar size and spacing, the position of the reinforcement within the slab thickness, the support plan, and the treatment of the reinforcement at each joint
+- Fiber product data for steel or synthetic macrofibers, with the proposed dosage, the batching and mixing procedure, and an ASTM C1609/C1609M test report at that dosage in the project mixture
+- Product data for load-transfer devices, including dowel diameter and length, plate dowel geometry, baskets, sleeves, and alignment hardware
+- Product data for the semi-rigid joint filler or elastomeric sealant, including hardness, cure time, and the manufacturer's required slab age before filling
+- Material source and gradation for a subbase that is not a dense-graded aggregate base
+- Trial placement plan, where a trial placement is required, giving its location, size, equipment, and the measurements to be taken on it
```datasheet
−label: Action submittals
+label: Action Submittals Required
type: checkbox
options:
− - Concrete mix design(s)
− - Reinforcement shop drawings / fiber dosage data
− - Joint layout drawing
− - Vapor retarder product data
− - Curing method and product data
− - Dowel, filler, and sealant data
+ - "Slab placement and joint layout plan"
+ - "Reinforcement placing drawings for the slab"
+ - "Fiber product data, dosage, and ASTM C1609 report"
+ - "Load-transfer device product data"
+ - "Joint filler or sealant product data"
+ - "Subbase material source and gradation"
+ - "Trial placement plan"
+default:
+ - "Slab placement and joint layout plan"
+ - "Reinforcement placing drawings for the slab"
+ - "Load-transfer device product data"
+ - "Joint filler or sealant product data"
+constraint: all_of
```
+### Slab concrete shall not be placed until the submittals covering that placement have been reviewed and returned.
+
## Informational Submittals {toc}
−### The Contractor shall submit the following informational items:
+### The Contractor shall submit the following before the first slab is placed, or as each item is produced:
−- Subgrade and subbase compaction test reports with Proctor reference and field densities.
−- Aggregate source and gradation reports per ASTM C33.
−- Concrete delivery tickets with batch time, water added, and admixture quantities.
−- Field test reports for slump, air, temperature, and compressive strength.
+- Subbase surface survey for each placement area, showing the measured elevation against the design elevation on the grid the Engineer of Record accepts
+- Pre-placement verification record for each placement, made in accordance with this standard
+- Trial placement report, where a trial placement is required, with the F-numbers measured on it and the sawing timing observed
+- Saw-cutting log recording, for each placement, the time of final finishing and the time each contraction joint was cut
+- Qualification of the party performing the floor flatness and levelness survey, and the calibration record for the instrument used
```datasheet
−label: Informational submittals
+label: Informational Submittals Required
type: checkbox
options:
− - Compaction test reports
− - Aggregate gradation reports
− - Concrete delivery tickets
− - Field test reports (slump, air, strength)
+ - "Subbase surface survey for each placement area"
+ - "Pre-placement verification record for each placement"
+ - "Trial placement report"
+ - "Saw-cutting log"
+ - "Floor survey party qualification and instrument calibration"
+default:
+ - "Subbase surface survey for each placement area"
+ - "Pre-placement verification record for each placement"
+ - "Saw-cutting log"
+ - "Floor survey party qualification and instrument calibration"
+constraint: all_of
```
## Closeout Submittals {toc}
−### The Contractor shall submit the following closeout items at substantial completion:
+### The Contractor shall submit the following before the slab work is accepted:
−- Floor flatness/levelness (FF/FL) survey reports per ASTM E1155.
−- As-built joint layout reflecting field deviations from the approved layout.
−- Moisture test results where required for flooring installation.
+- Floor flatness and levelness reports per ASTM E1155 for every test section, identifying the section, the date and time of placement and of measurement, the overall and local F-numbers, and conformance to the specified values
+- As-built joint layout, recording every departure from the accepted joint layout plan
+- Joint filling record, giving the slab age at filling, the product, and the lots used for each placement
+- Record of every random crack reported to the Engineer of Record, with its location, measured width, and the disposition directed
+- Thickness verification record for each placement
```datasheet
−label: Closeout submittals
+label: Closeout Submittals Required
type: checkbox
options:
− - FF/FL survey reports
− - As-built joint layout
− - Moisture test results
+ - "Floor flatness and levelness reports per ASTM E1155"
+ - "As-built joint layout"
+ - "Joint filling record"
+ - "Random crack reports and dispositions"
+ - "Thickness verification record"
+default:
+ - "Floor flatness and levelness reports per ASTM E1155"
+ - "As-built joint layout"
+ - "Joint filling record"
+ - "Random crack reports and dispositions"
+ - "Thickness verification record"
+constraint: all_of
```
# Quality Assurance {toc}
−## The slab-on-grade is a single integrated system, and acceptance depends on documented control of the subgrade, the concrete, and the finished surface in equal measure. {note}
+## Pre-Slab Conference {toc}
−## The most damaging SOG failures — random cracking, curling, joint spalling, and flooring adhesive failure — usually trace to a controllable process that was never tested, not to a hidden material defect. Quality assurance for SOG is therefore weighted heavily toward field verification at the moment work is performed. {note}
+### A conference shall be held before the subbase is placed beneath the first slab.
−## The Contractor shall hold a pre-placement conference with the Engineer of Record, testing agency, and finishing crew before the first placement.
+### The conference shall be attended by the Contractor's superintendent, the concrete subcontractor and the finishing foreman, the ready-mixed concrete supplier, the testing agency, the sawing subcontractor, the flooring installer where a moisture-sensitive covering is scheduled on the slab, and the Engineer of Record.
−## The Contractor shall not place concrete on a subgrade or subbase that has not passed compaction testing.
+### The conference agenda shall cover the subbase and its surface tolerance, the vapor retarder decision and the sequence it fixes, the placement sequence and strike-off method, the reinforcement or fiber and its support, the joint layout and the sawing method and timing, the load-transfer devices, the F-numbers and how they will be measured, the finishing and curing method assigned to the scheduled floor covering, the strength required before construction traffic, and the procedure for reporting random cracks.
−## The Contractor shall not place concrete on frozen, saturated, or unstable subgrade.
+### A floor is built in one pass by a crew that cannot stop to consult the documents, and the decisions that govern its quality are the ones every party in the room has to carry out in the same order on the same day. The conference exists so that the finishing foreman, the saw operator, and the testing technician have agreed on timing before the first truck arrives rather than at the first joint. {note}
−## Subgrade and subbase compaction shall be field-tested at the frequency specified, with each lift verified before the next is placed.
+## Trial Placement {toc}
+### A trial placement is a production-sized panel built with the production crew, mixture, equipment, and method before the floor itself, and measured as the floor will be measured. It costs a day and a panel of concrete, and it buys the F-numbers, the sawing window, and the finishing timing for the actual mixture and the actual weather instead of the values assumed in the plan. It earns its cost where the specified tolerances are tighter than the crew has recently achieved, where the mixture carries fibers or a shrinkage limit the finishers have not worked with, or where the floor will remain exposed as the finished surface. {note}
+
+### Whether a trial placement is required before the first production slab shall be as indicated in the datasheet.
+
```datasheet
−label: Compaction test frequency
−type: select
+label: Trial Placement Before Production Slabs
+type: radio
options:
− - 1 test per 2,000 sq ft per lift
− - 1 test per 5,000 sq ft per lift
− - 1 test per 10,000 sq ft per lift
−unit: sq ft per test
−default: 1 test per 5,000 sq ft per lift
+ - "Required before the first production placement"
+ - "Not required"
+default: "Not required"
```
−## Concrete field tests shall be taken at the frequency required by the project specifications, with a minimum of one set of strength cylinders per 100 cubic yards or per day of placement.
+### Where a trial placement is required, it shall be of not less than the area indicated in the datasheet and shall be built with the same subbase, vapor retarder, reinforcement or fiber, mixture, crew, equipment, strike-off method, and finishing and curing method as the production slabs.
−## The testing agency shall verify slump, air content, and concrete temperature on each load sampled.
+```datasheet
+label: Trial Placement Area
+type: range
+unit: "ft²"
+options:
+ min: 500
+ max: 5000
+ setpoints: [500, 1000, 1500, 2000, 3000, 5000]
+constraint: min
+```
−# Environmental and Service Conditions {toc}
+### The trial placement shall be surveyed for F-numbers and its contraction joints cut by the production method, and the results shall be reviewed with the Engineer of Record before the first production placement.
−## Slab thickness, reinforcement, and joint spacing are governed by the service loads the floor must carry, which must be defined before any element is sized. {note}
+### Where the Engineer of Record accepts the trial placement in writing, it shall remain as part of the work; otherwise the Contractor shall remove it at no cost to the Owner.
−## A warehouse floor carrying loaded rack posts and narrow-aisle lift trucks demands a completely different design than a retail sales floor carrying uniform live load. Stating the governing loads converts the slab from a guess into an engineered element. {note}
+## Floor Survey {toc}
−## The design loads imposed on the slab shall be defined and the slab designed to resist them per ACI 360R-10.
+### The floor flatness and levelness survey shall be performed by the party indicated in the datasheet.
```datasheet
−label: Governing service load type
+label: Party Performing the Floor Flatness and Levelness Survey
type: radio
options:
− - Uniform distributed load only
− - Rack / storage post loads
− - Forklift / hard-wheeled vehicle loads
− - Concentrated equipment / point loads
−default: Uniform distributed load only
+ - "Independent testing agency engaged by the Owner"
+ - "Independent testing agency engaged by the Contractor"
+ - "Contractor's own personnel using a calibrated instrument"
+default: "Independent testing agency engaged by the Owner"
```
−```datasheet
−label: Design uniform live load
−type: range
−min: 100
−max: 1000
−step: 50
−unit: psf
−default: 250
−```
+### An Owner-engaged agency makes the survey an acceptance test independent of the party whose work it measures, at the Owner's cost; a Contractor-engaged agency keeps the same instrument and procedure on the Contractor's side of the contract, which suits a floor the Contractor is also responsible for correcting; the Contractor's own personnel can survey within the 72 hour window on a remote site where no agency is available, at the cost of an acceptance record produced by the party it judges. {note}
−## The subgrade modulus of subgrade reaction (k-value) used in design shall be established by geotechnical evaluation of the prepared subgrade.
+### The survey instrument shall be of a type ASTM E1155 permits and shall carry a calibration record not older than one year at the time of the survey.
+# Design Basis {toc}
+
+## ACI 360R sizes a slab on ground for the loads that cross it against the stiffness of the ground that supports it. Three inputs decide the outcome: the modulus of subgrade reaction, the loads, and the crack-control strategy, because the strategy fixes the joint spacing and the joint spacing fixes how much of the slab's capacity is spent on shrinkage restraint before any load is applied. {note}
+
+## The modulus of subgrade reaction used in the slab design shall be as indicated in the datasheet.
+
```datasheet
−label: Design modulus of subgrade reaction (k)
+label: Modulus of Subgrade Reaction
type: range
−min: 50
−max: 400
−step: 25
unit: pci
−default: 150
+drawing_ref: "the geotechnical report"
+options:
+ min: 25
+ max: 500
+ step: 5
+default: deferred
+constraint: exact
```
−## The k-value quantifies how much the soil deflects under load and is the single most influential soil parameter in slab thickness design. A subbase amplifies the effective k-value, which is one reason a granular subbase is specified even where bearing is otherwise adequate. {note}
+## The modulus is a measure of how much the ground deflects under a loaded plate, and it is the single most influential soil input to slab thickness. It is a property of the prepared subgrade together with the subbase, not of the native soil alone, which is why a granular subbase is specified even where bearing is already adequate: it raises the effective modulus and, more importantly, makes it uniform across the floor. {note}
−## Where the slab will receive moisture-sensitive flooring, the design shall account for under-slab moisture control through the vapor retarder and curing method.
+## The slab design shall be based on the uniform loads, rack and post loads, and vehicle wheel and axle loads indicated on [[drawing: the structural general notes]].
−# Subgrade and Subbase {toc}
+## The crack-control strategy for the slab shall be as indicated in the datasheet.
−## A uniform, properly compacted subgrade is the foundation of a crack-free slab, because differential settlement produces cracks that no concrete quality can prevent. {note}
−
−## Slabs do not span; they are supported continuously. When a soft spot or uncompacted backfill settles under a loaded slab, the slab bends to follow it and cracks. Because such cracks look identical to shrinkage cracks, they are routinely and wrongly blamed on the concrete. Verified, uniform compaction is the only defense. {note}
−
−## The subgrade shall be compacted to the specified percentage of maximum dry density determined by the referenced Proctor method.
−
```datasheet
−label: Subgrade compaction requirement
+label: Crack-Control Strategy
type: radio
options:
− - 95% of Standard Proctor maximum dry density (ASTM D698)
− - 98% of Standard Proctor maximum dry density (ASTM D698)
− - 95% of Modified Proctor maximum dry density (ASTM D1557)
− - 98% of Modified Proctor maximum dry density (ASTM D1557)
−default: 95% of Standard Proctor maximum dry density (ASTM D698)
+ - "Plain concrete, with cracking controlled by contraction joints alone"
+ - "Welded wire reinforcement"
+ - "Deformed reinforcing bars"
+ - "Steel fiber reinforcement"
+ - "Synthetic macrofiber reinforcement"
+ - "Shrinkage-compensating concrete"
+ - "Post-tensioned, unbonded tendons"
```
−## The subgrade moisture content at compaction shall be maintained within the range specified relative to optimum.
+## A slab on ground cracks because the concrete shrinks while the ground holds it still, and every strategy on the list is a different answer to where that crack goes. A plain slab puts it at a closely spaced contraction joint and relies on nothing else, which is economical where the floor is lightly and uniformly loaded and the joint count is acceptable. Welded wire and deformed bars do not stop the crack from forming; they hold it tight between joints so it stays narrow, and they permit the joints to be spaced farther apart at the cost of placing and supporting steel. Steel and synthetic macrofibers do the same job distributed through the section, with no steel to chair and no position to verify, at the cost of a mixture that batches and finishes differently and a surface on which fibers can show. Shrinkage-compensating concrete expands against its reinforcement during the first days and then shrinks back to roughly its original length, so the slab arrives at service with little net shrinkage and few joints, at the cost of a cement the supplier has to source and a curing regime that cannot be shortened. Post-tensioning puts the slab in compression so it does not crack at all and needs no contraction joints, and it is the strategy for large jointless floors and for slabs that must bridge expansive or compressible soil, at the cost of a stressing operation and tendon layout the other strategies do not need. {note}
+## Where the slab is of shrinkage-compensating concrete, the concrete, its reinforcement, and the curing it requires shall conform to ACI 223R.
+
+## Where the slab is post-tensioned, strand, anchorages, sheathing, and stressing shall conform to [[sync/post-tensioned-concrete]] and to PTI M10.2.
+
+## Where a post-tensioned slab also serves as the foundation of the building on expansive or compressible soil, it shall be designed in accordance with PTI DC10.5.
+
+# Slab Thickness {toc}
+
+## The slab thickness shall be as indicated in the datasheet.
+
```datasheet
−label: Compaction moisture tolerance
+label: Slab Thickness
type: range
−min: -3
−max: 3
−step: 1
−unit: '% of optimum'
−setpoints: [-3, -2, 0, 2, 3]
−default: 0
+unit: in
+drawing_ref: "the slab-on-grade schedule on the structural drawings"
+options:
+ min: 3.5
+ max: 24
+ step: 0.5
+default: deferred
+constraint: exact
```
−## Soft, yielding, or organic material encountered in the subgrade shall be removed and replaced with approved engineered fill compacted to the specified density.
+## The slab thickness shall be not less than the prescriptive minimum that [[parameter: adopted-building-code]] sets for a concrete floor slab on ground.
−## Engineered fill shall be placed in lifts not exceeding the specified maximum loose thickness and compacted before the next lift is placed.
+## Thickness is the design output, not a rule of thumb. It is set by the governing wheel, post, or uniform load against the modulus of subgrade reaction, and it is the dimension that a high spot in the subbase silently reduces exactly where a loaded wheel will find it. The thickness tolerance and the subbase surface tolerance are therefore specified together, because the second is what protects the first. {note}
+## The thickness of the placed slab shall be within the tolerance ACI 117 specifies for slabs on ground.
+
+## Slab thickness shall be verified for each placement as this standard requires under Field Quality Control.
+
+# Slab Edge at the Building Perimeter {toc}
+
+## The relation between the slab edge and the foundation decides whether the floor moves with the building or independently of it. A turned-down edge makes the slab its own perimeter foundation, which is the usual construction for a pre-engineered metal building or a lightly loaded single-story structure on competent soil. A free edge separated from the foundation wall by a full-depth isolation joint lets the floor shrink and curl without dragging on a wall that is not moving, which is why it is the usual detail where the building has its own footings. An edge resting on a ledge or haunch cast into the foundation keeps the slab edge from settling with the backfill beside the wall while a bond breaker still lets it move horizontally. A doweled edge ties the slab to the wall for load transfer where the wall and the slab are designed to act together, and it restrains the slab in return. {note}
+
+## The slab edge at the building perimeter shall be as indicated in the datasheet.
+
```datasheet
−label: Maximum fill lift thickness (loose)
−type: range
−min: 6
−max: 12
−step: 2
−unit: in
−default: 8
+label: Slab Edge at the Building Perimeter
+type: radio
+options:
+ - "Monolithic turned-down edge serving as an integral grade beam"
+ - "Free edge separated from the foundation by a full-depth isolation joint"
+ - "Edge bearing on a foundation ledge or haunch over a bond breaker"
+ - "Edge doweled to the foundation wall"
```
−## A granular subbase increases the effective subgrade modulus, provides a level working platform for placing concrete, and gives a capillary break above the soil. {note}
+## Turned-down edge and thickened edge dimensions and reinforcement shall be as shown on [[drawing: the foundation plan and slab edge details]].
−## Even where the native soil bears adequately, a crushed-stone subbase is specified on most SOG projects because it produces a uniform, free-draining surface that finishers can work from and that protects the vapor retarder during placement. {note}
+## A turned-down edge that serves as the perimeter foundation of the building shall bear below [[parameter: frost-depth]], or shall be designed as a frost-protected shallow foundation in accordance with [[parameter: adopted-building-code]].
−## A granular subbase shall be provided where specified, of the type and thickness selected below.
+## Thickened slab sections beneath interior bearing walls, rack post lines, and equipment shall be located as shown on [[drawing: the foundation plan]].
+## Turned-down edges and thickened sections shall be placed monolithically with the slab they stiffen.
+
+## Where a thickened section cannot be placed monolithically with the slab, the Contractor shall notify the Engineer of Record, who shall direct in writing the location and the load transfer at the resulting construction joint.
+
+## Bars in a turned-down edge or thickened section shall be furnished, bent, and spliced under [[sync/concrete-reinforcement]] and positioned as the slab edge details show.
+
+## Where the slab edge bears on a ledge or haunch, a bond breaker shall be placed on the bearing surface before the slab is placed, and no reinforcement shall cross from the slab into the foundation.
+
+# Subgrade Beneath the Slab {toc}
+
+## Uniform support matters more to a slab on ground than strong support. A slab does not span, so when a soft pocket, an uncompacted trench, or a lens of organic material settles under a loaded panel the slab follows it and cracks, and the crack looks exactly like a shrinkage crack. Such cracks are routinely blamed on the concrete. The only defense is a subgrade that was compacted, proof-rolled, and accepted before anything was placed on it, and that was not disturbed afterward. {note}
+
+## The subgrade shall be excavated or filled, compacted, proof-rolled, and accepted in accordance with [[sync/earthwork]] before any material is placed on it.
+
+## Where soft or yielding areas are found after the subgrade was accepted, the Contractor shall correct them under [[sync/earthwork]] before placing anything over them.
+
+## Backfill of utility trenches crossing beneath the slab shall be compacted under [[sync/earthwork]] to the target for fill beneath slabs and shall be accepted before it is covered.
+
+## Where the geotechnical report requires lime, cement, or fly ash treatment of the subgrade, the treatment shall be performed under [[sync/soil-stabilization]].
+
+## Where [[parameter: seasonal-high-groundwater-elevation]] lies within 2 ft of the underside of the slab, the Engineer of Record shall determine whether an under-slab drainage layer is required, and any drainage layer shall be as specified under [[sync/subdrainage]].
+
+## Where no subbase is provided, the subgrade surface shall be fine-graded to the elevation tolerance this standard sets for the subbase surface.
+
+# Granular Subbase {toc}
+
+## A subbase buys three things at once: a uniform, higher modulus of subgrade reaction across the whole floor; a capillary break between the soil and the slab; and a working platform that trucks, pump hoses, and finishers can operate on without rutting the subgrade. A dense-graded crushed aggregate base provides all three and trims to a tight surface. An open-graded crushed stone layer provides the strongest capillary break and drains, but its surface cannot be trimmed to tolerance or walked on without displacing stone, so it is finished with a fine-graded choker course on which the vapor retarder lies. A cushion of sand or screenings alone gives the trimmable surface and some protection to the retarder without the stiffness or the drainage of a stone layer. No subbase at all places the slab on the prepared subgrade, which the geotechnical engineer of record permits where the subgrade is granular, uniform, and already drains. {note}
+
+## The subbase beneath the slab shall be of the type indicated in the datasheet.
+
```datasheet
−label: Subbase type
+label: Subbase Type
type: radio
options:
− - None (slab on prepared subgrade)
− - Crushed stone / crushed gravel
− - Lean concrete base (LCB)
−default: Crushed stone / crushed gravel
+ - "Dense-graded crushed aggregate base"
+ - "Open-graded crushed stone capillary break with a fine-graded choker course at the surface"
+ - "Fine-graded compactible cushion of sand or stone screenings only"
+ - "No subbase, with the slab placed on the prepared subgrade"
+default: "Dense-graded crushed aggregate base"
```
+## The subbase thickness shall be as indicated in the datasheet.
+
```datasheet
−label: Granular subbase thickness
+label: Subbase Thickness
type: range
−min: 4
−max: 12
−step: 2
unit: in
−default: 4
+drawing_ref: "the slab-on-grade section on the structural drawings or the geotechnical report"
+options:
+ min: 2
+ max: 24
+ step: 1
+default: deferred
+constraint: exact
```
−## The subbase shall be compacted and trimmed to the specified elevation tolerance to control slab thickness.
+## A dense-graded crushed aggregate base shall be furnished, placed in lifts, and compacted in accordance with [[sync/aggregate-base-course]].
−## A subbase that is high in spots robs the slab of thickness exactly where it may be thinnest, while low spots waste concrete. Trimming to tolerance protects the design thickness. {note}
+## Open-graded crushed stone shall be placed in lifts not exceeding 6 in. and shall be compacted with vibratory equipment until the surface no longer moves under the compactor, as confirmed by the geotechnical engineer of record.
−## The compacted subbase surface shall be maintained within the specified elevation tolerance before vapor retarder placement.
+## A choker course or cushion shall be a fine-graded, compactible material placed and compacted to a surface that the vapor retarder can be laid on and walked on without displacement.
+## The finished subbase surface shall be within the elevation tolerance indicated in the datasheet of the design elevation.
+
```datasheet
−label: Subbase surface elevation tolerance
+label: Subbase Surface Elevation Tolerance
type: range
−min: 0
−max: 1
−step: 0.25
unit: in
−setpoints: [0.5, 0.75, 1]
+options:
+ min: 0.25
+ max: 1
+ setpoints: [0.25, 0.5, 0.75, 1]
default: 0.75
+constraint: max
```
−# Vapor Retarder {toc}
+## A high spot in the subbase takes its height out of the slab, and a low spot is paid for in concrete; a tolerance of three-quarters of an inch is the common pairing with the ACI 117 thickness tolerance, and a tighter value is set where the slab is thin, where the floor is a defined-traffic floor whose thickness governs its stiffness, or where the quantity of concrete is being controlled closely. {note}
−## The vapor retarder placement plane is a recurring source of RFIs and flooring failures, so this standard states the placement position explicitly. {note}
+## The finished subbase surface shall be surveyed on the grid the Engineer of Record accepts, and the survey shall be submitted before the vapor retarder or the slab is placed over it.
−## Two practices exist: placing the retarder directly under the slab, and placing it lower on a granular blotter layer. ACI 302.1R-15 directs placement directly under the slab for floors that will receive moisture-sensitive flooring, because a blotter layer above the retarder traps mix and bleed water that has nowhere to drain, increasing surface bleeding, scaling, and delamination. Material selection, permeance, and seaming are governed by [[sync/vapor-retarders]]. {note}
+## Construction traffic on the finished subbase shall be limited to the vehicles the placement plan identifies, and ruts, displaced material, and contamination shall be regraded and recompacted before the slab is placed.
−## The vapor retarder shall be placed directly beneath the slab, in contact with the bottom of the concrete, unless the Engineer of Record directs a blotter-layer placement in writing.
+## At the time concrete is placed, the subbase or subgrade surface beneath the slab shall be damp, with no standing water, mud, ice, snow, or frozen material.
+## Where no vapor retarder is provided, the subbase or subgrade surface shall be wetted before concrete is placed so that it does not absorb water from the concrete, with no free water remaining on the surface at placement.
+
+## A dry absorptive base pulls water out of the bottom of the slab as it is placed, which stiffens the bottom, starves the hydration there, and sets up the moisture gradient that curls the slab; a saturated base supplies water the slab cannot shed and keeps the bottom wet for months. Damp with no free water is the condition between the two. {note}
+
+# Vapor Retarder Beneath the Slab {toc}
+
+## Whether a vapor retarder is placed beneath the slab is a design decision about where the slab is allowed to dry, not a detail. With a retarder directly beneath it the slab dries upward only, which takes longer but ends, and the floor covering above it sees no soil moisture. Without one the slab dries from both faces and curls less, but soil moisture moves through it indefinitely, so any adhesive, coating, or covering above it is exposed to that moisture for the life of the floor. ACI 302.1R and ACI 302.2R work through the choice as a sequence of questions about the floor covering, the occupancy, and the soil, and ASTM F710 requires an effective retarder beneath any slab that will receive resilient flooring. {note}
+
+## Whether a vapor retarder is provided beneath the slab shall be as indicated in the datasheet.
+
```datasheet
−label: Vapor retarder placement plane
+label: Vapor Retarder Beneath the Slab
type: radio
options:
− - Directly under slab (ACI 302.1R-15 recommendation)
− - On blotter layer 2 to 4 in. below slab
−default: Directly under slab (ACI 302.1R-15 recommendation)
+ - "Provided"
+ - "Not provided"
+default: "Provided"
```
−## The vapor retarder class shall be selected per ASTM E1745 to suit the floor covering and moisture sensitivity of the space.
+## A retarder is omitted where the slab will remain bare or will receive only a breathable covering, where the space is unconditioned, and where the geotechnical engineer of record confirms that the subbase drains and the soil carries no moisture source the slab needs protection from; the floors of an open warehouse, an unconditioned industrial bay, or a covered loading area are the usual cases. Omitting it where any adhered or coated finish is later installed converts a saved roll of polyethylene into a flooring failure. {note}
+## Where a moisture-sensitive floor covering, coating, or adhesive is scheduled on the slab, a vapor retarder shall be provided beneath it unless the Engineer of Record directs otherwise in writing.
+
+## Where a vapor retarder is provided, its product, class, permeance, position, laps, seams, penetration sealing, repair, and protection before the pour shall conform to [[sync/vapor-barriers-under-slab]].
+
+## The vapor retarder shall not be placed until the subbase surface has been accepted and surveyed.
+
+## Where termiticide soil treatment is specified, it shall be applied and accepted under [[sync/soil-treatment-for-termite-control]] before the membrane is laid over the treated soil.
+
+## Bar supports, dowel baskets, edge forms, and stakes shall be set on the vapor retarder without puncturing it, and punctures made by supports, stakes, or traffic shall be repaired under [[sync/vapor-barriers-under-slab]] before concrete is placed.
+
+## A retarder directly beneath the slab removes the base that would otherwise absorb bleed water, so a mixture placed on it bleeds longer, finishes later, and curls more than the same mixture on a granular base. The adjustments that compensate, a lower water content, a larger aggregate, and a cementitious content that does not depend on the base to take water away, are mixture decisions made under [[sync/cast-in-place-concrete]] with the retarder in view. {note}
+
+# Concrete for the Slab {toc}
+
+## Slab concrete shall be the slab-on-grade mixture class specified under [[sync/cast-in-place-concrete]], with the specified compressive strength, the drying shrinkage limit, the water-cementitious materials ratio, and the nominal maximum aggregate size assigned to that class.
+
+## Where the contraction joint spacing exceeds 30 times the slab thickness, or where the slab will remain exposed as the finished floor, the Engineer of Record shall assign a drying shrinkage limit to the slab mixture class under [[sync/cast-in-place-concrete]].
+
+## Strength is the property a cylinder measures and shrinkage is the property a floor exhibits, and the two are set by different parts of the mixture. A floor cracks between its joints, curls at them, and spalls along them in proportion to how much water and paste it carried, not to how many pounds per square inch it reached, so a slab mixture is controlled through its water content, its aggregate volume, and a measured shrinkage limit where joint spacing or an exposed finish makes shrinkage the governing property. {note}
+
+## Where fibers are part of the crack-control strategy, the slab concrete shall also conform to ASTM C1116/C1116M.
+
+# Reinforcement Within the Slab {toc}
+
+## Reinforcement in a slab on ground controls the width of the cracks that form; it does not prevent them. A light mat of welded wire or bars adds nothing to the slab's capacity to carry load and nothing to its resistance to cracking; its entire value is in holding a crack closed after it opens, which it does only if it is in the upper part of the slab where the crack opens widest and only if it is still there, in that position, after the concrete is placed. {note}
+
+## Welded Wire Reinforcement {toc}
+
+### Welded wire reinforcement in the slab shall conform to ASTM A1064/A1064M and shall be furnished in the form indicated in the datasheet.
+
```datasheet
−label: Vapor retarder class (ASTM E1745)
+label: Welded Wire Reinforcement Form
type: radio
options:
− - Class A
− - Class B
− - Class C
−default: Class A
+ - "Flat sheets"
+ - "Rolls"
+default: "Flat sheets"
```
−## The vapor retarder shall be installed per ASTM E1643, with laps, seams, and penetration sealing as required by [[sync/vapor-retarders]].
+### Reinforcement from a roll holds the curvature it was wound to, and in a slab the spring-back lifts the mat off its supports and up through the surface in one place while it lies on the subbase in another; flat sheets lie where they are chaired, which is why ACI 301 requires them and rolls are selected only for the lightest mats, where the Contractor will flatten and secure them in a way the Engineer of Record accepts. {note}
−## Vapor retarder penetrations for pipes, conduit sleeves, and column anchors shall be sealed so the membrane remains continuous. {note}
+### Where rolls are selected, the reinforcement shall be flattened before placement and tied to its supports so that no part of the mat rises above or falls below its specified position during concrete placement.
−## An unsealed penetration is a direct moisture path that negates the entire barrier and commonly surfaces as adhesive failure under occupancy. Sealing every penetration is not optional detailing — it is what makes the retarder function. {note}
+### The welded wire reinforcement sheet designation shall be as indicated in the datasheet.
−## Every penetration through the vapor retarder shall be sealed to maintain continuity of the moisture barrier.
+```datasheet
+label: Welded Wire Reinforcement Sheet Designation
+type: text
+drawing_ref: "the slab-on-grade schedule on the structural drawings"
+default: deferred
+```
−# Concrete {toc}
+### Sheets shall be lapped not less than one spacing of the cross wires plus 2 in. for plain wire, and not less than the lap length ACI 318 requires for deformed wire, and the laps shall be tied.
−## Specifying a strength class alone does not produce a durable floor; the water-cementitious ratio and aggregate gradation control the shrinkage and surface quality that determine how the slab performs. {note}
+## Deformed Bars {toc}
−## A high-strength mix with an uncontrolled w/cm and a poor gradation will shrink, curl, crack, and dust despite passing its cylinder breaks. The mix design must control strength, water, aggregate, and admixtures together. Structural mix proportioning principles are detailed in [[sync/cast-in-place-concrete]]; this section sets the SOG-specific limits. {note}
+### Deformed bars in the slab shall be furnished, bent, and spliced under [[sync/concrete-reinforcement]].
−## The concrete compressive strength at 28 days shall be not less than the specified value.
+### The bar designation shall be as indicated in the datasheet.
```datasheet
−label: Specified compressive strength (f'c) at 28 days
+label: Reinforcing Bar Designation
type: range
−min: 3000
−max: 5000
−step: 500
−unit: psi
−default: 4000
+drawing_ref: "the slab-on-grade schedule on the structural drawings"
+options:
+ min: 3
+ max: 6
+ step: 1
+default: deferred
+constraint: exact
```
−## The water-cementitious materials ratio shall not exceed the specified maximum.
+### The bar spacing in each direction shall be as indicated in the datasheet.
```datasheet
−label: Maximum water-cementitious materials ratio
+label: Reinforcing Bar Spacing Each Way
type: range
−min: 0.40
−max: 0.55
−step: 0.01
−unit: w/cm
−setpoints: [0.4, 0.45, 0.5, 0.55]
−default: 0.50
−```
−
−## The nominal maximum aggregate size shall be the largest size consistent with slab thickness and reinforcement clearance, to reduce paste content and shrinkage.
−
−```datasheet
−label: Nominal maximum aggregate size
−type: select
−options:
− - 3/8 in
− - 1/2 in
− - 3/4 in
− - 1 in
− - 1-1/2 in
unit: in
−default: 1 in
+drawing_ref: "the slab-on-grade schedule on the structural drawings"
+options:
+ min: 6
+ max: 24
+ step: 1
+default: deferred
+constraint: exact
```
−## Concrete aggregates shall conform to ASTM C33 for grading and quality.
+## Position and Support {toc}
−## The slump at the point of placement shall be within the specified range, measured after any permitted water or admixture addition.
+### Welded wire reinforcement and bars in the slab shall be positioned at the depth below the finished surface indicated in the datasheet.
```datasheet
−label: Slump at point of placement
+label: Reinforcement Depth Below the Finished Surface
type: range
−min: 3
−max: 6
−step: 0.5
unit: in
−setpoints: [3, 4, 5, 6]
−default: 5
+options:
+ min: 1.5
+ max: 4
+ setpoints: [1.5, 2, 2.5, 3, 3.5, 4]
+default: 2
+constraint: exact
```
−## Supplementary cementitious materials may be used within the proportions specified to reduce permeability and heat of hydration. {note}
+### A shrinkage crack opens widest at the top of the slab and narrows toward the bottom, so the steel that holds it closed belongs in the upper part of the section, 2 in. below the surface on a slab of ordinary thickness and at about one-third of the depth on a thick one. Placed higher it loses its cover and rusts at the first crack; placed at mid-depth or below it is simply not where the crack is. {note}
−## Fly ash and slag improve workability and long-term durability, but excessive replacement can delay set and bleeding, complicating finishing on a slab where surface quality is paramount. The proportions below bound the substitution. {note}
+### Reinforcement shall be supported on bar supports furnished under [[sync/concrete-accessories]], spaced not more than the distance indicated in the datasheet in each direction.
−## The maximum permitted fly ash and/or slag replacement of cementitious content shall be specified to bound substitution while preserving the finishing quality of the slab surface.
−
```datasheet
−label: Maximum SCM replacement (fly ash and/or slag)
+label: Bar Support Spacing Beneath Slab Reinforcement
type: range
−min: 0
−max: 50
−step: 5
−unit: '% of cementitious'
−default: 25
+unit: in
+options:
+ min: 24
+ max: 48
+ setpoints: [24, 30, 36, 48]
+constraint: max
```
−## A shrinkage-reducing admixture should be specified for large jointless placements or floors with tight crack-width limits. {note}
+### Bar supports bearing on the vapor retarder shall have plate or precast bases that do not puncture the membrane.
−# Reinforcement and Fiber {toc}
+### Reinforcement shall not be laid on the subbase or the vapor retarder and lifted during concrete placement.
−## Reinforcement in a ground-supported slab controls crack width; it does not prevent cracking, and confusing the two leads to under- or over-designed slabs. {note}
+### Reinforcement lifted into position by hand from beneath the fresh concrete ends up wherever the hook left it, which the record of every cored slab shows is the bottom. Supports close enough that a finisher's weight between them does not push the mat down are the only method that puts the steel where the design assumes it. {note}
−## A SOG cracks because concrete shrinks while the subgrade restrains it. Temperature/shrinkage reinforcement does not stop that crack from forming — it holds the crack tight so it stays narrow and does not progress. Fiber reinforcement works the same way at the section level. Structural reinforcement detailing, splices, and placement tolerances are governed by [[sync/concrete-reinforcement]]. {note}
+### The position of the reinforcement within the slab shall be within the tolerance of ACI 117.
−## Where conventional reinforcement is specified, it shall be welded wire reinforcement conforming to ASTM A1064 or deformed bars as scheduled.
+## Reinforcement at Contraction Joints {toc}
+### The treatment of the reinforcement at contraction joints shall be as indicated in the datasheet.
+
```datasheet
−label: Conventional reinforcement type
+label: Reinforcement at Contraction Joints
type: radio
options:
− - Welded wire reinforcement (flat sheets, ASTM A1064)
− - Deformed reinforcing bar grid
− - None (fiber or plain slab)
−default: Welded wire reinforcement (flat sheets, ASTM A1064)
+ - "Discontinued at every contraction joint"
+ - "Continued through the joint with alternate wires or bars cut"
+ - "Continued through the joint without interruption"
+default: "Discontinued at every contraction joint"
```
−## Welded wire reinforcement shall be supported on chairs at the specified height within the slab so it is positioned, not left on the subgrade.
+### Steel that crosses a contraction joint restrains it, and a joint that cannot open does not relieve the shrinkage, which then cracks the panel somewhere else. Discontinuing the reinforcement at every joint lets the joint work and relies on dowels or aggregate interlock for load transfer across it. Cutting alternate wires or bars halves the restraint while keeping some steel across the joint to hold it from opening wide, a compromise used where no dowels are provided and the joint will be filled. Continuing the reinforcement without interruption is the detail for a joint that is intended not to open, which makes sense only where the design accepts cracking between joints or where the steel area is large enough to hold those cracks tight. {note}
+### Reinforcement shall not cross an isolation joint.
+
+### Reinforcement shall be stopped at construction joints, with load transferred by the devices this standard requires, unless the accepted joint layout plan shows it continuing.
+
+## Fiber Reinforcement {toc}
+
+### Steel fibers shall conform to ASTM A820/A820M and shall be of the type indicated in the datasheet.
+
```datasheet
−label: Reinforcement position from top of slab
−type: range
−min: 1.5
−max: 3
−step: 0.5
−unit: in
−default: 2
+label: Steel Fiber Type per ASTM A820
+type: select
+options:
+ - "Type I, cold-drawn wire"
+ - "Type II, cut sheet"
+ - "Type III, melt-extracted"
+ - "Type IV, mill cut"
+ - "Type V, modified cold-drawn wire"
+default: "Type I, cold-drawn wire"
```
−### Reinforcement laid directly on the subgrade and "hooked up" during placement ends up at the bottom of the slab where it does nothing for surface crack control. {note}
+### Cold-drawn wire fibers, usually with hooked or crimped ends, give the highest residual strength per pound and are the type the floor market is built around; cut sheet and mill-cut fibers are shorter and stiffer, pump and finish more easily, and deliver less post-crack toughness per pound; melt-extracted fibers are the corrosion-resistant stainless product for an exposed or aggressive environment; modified cold-drawn wire covers the proprietary geometries that trade anchorage against fiber count at a fixed dosage. {note}
−## Where steel fiber reinforcement is specified, the dosage shall be not less than the specified value, uniformly distributed throughout the mix.
+### Where steel fibers are the crack-control strategy, the dosage shall be not less than that indicated in the datasheet.
```datasheet
−label: Steel fiber dosage
+label: Steel Fiber Dosage
type: range
−min: 15
−max: 60
−step: 5
−unit: lb/cy
−default: 35
+unit: "lb/yd³"
+options:
+ min: 15
+ max: 100
+ step: 5
+constraint: min
```
−## Where synthetic macro-fiber reinforcement is specified, the dosage shall be not less than the specified value.
+### Synthetic macrofibers shall conform to ASTM D7508/D7508M.
+### Where synthetic macrofibers are the crack-control strategy, the dosage shall be not less than that indicated in the datasheet.
+
```datasheet
−label: Synthetic macro-fiber dosage
+label: Synthetic Macrofiber Dosage
type: range
−min: 3
−max: 12
−step: 0.5
−unit: lb/cy
−default: 5
+unit: "lb/yd³"
+options:
+ min: 3
+ max: 12
+ step: 0.5
+constraint: min
```
−## Fibers shall be charged and mixed per the manufacturer's procedure so that balling is avoided and distribution is uniform.
+### Steel fibers and synthetic macrofibers occupy different parts of the dosage scale for the same crack-control effect because they differ by roughly an order of magnitude in density, so a dosage is meaningful only beside the fiber it was set for; the design value that compares them is the residual strength the fiber-reinforced concrete develops in the ASTM C1609/C1609M beam test at the proposed dosage. {note}
−## Post-tensioned slabs on grade shall be designed per PTI DC80.3 with unbonded tendons and edge beams as required for the soil and loading.
+### The fiber type and dosage shall provide the residual strength under ASTM C1609/C1609M that the slab design under ACI 360R and ACI 544.4R requires, as demonstrated by the test report submitted.
−# Slab Thickness {toc}
+### Fibers shall be added to the mixture and mixed by the method the fiber manufacturer publishes, so that they are distributed through the load without balling.
−## Slab thickness is the result of a load analysis, not a rule of thumb, and selecting it from joint-spacing tables alone leaves the slab undersized for concentrated loads. {note}
+### A load in which fiber balls are observed at discharge shall be rejected at the Contractor's cost.
−## ACI 360R-10 provides Westergaard and finite-element methods that size the slab for the governing wheel, post, or uniform load against the design k-value. The datasheet below records the design output; it is not a substitute for the analysis. {note}
+### Whether microsynthetic fibers for plastic shrinkage control are included in the slab mixture shall be as indicated in the datasheet.
−## The slab thickness shall be the greater of the thickness required by the load analysis per ACI 360R-10 and the prescriptive minimum of the adopted building code.
−
```datasheet
−label: Design slab thickness
−type: range
−min: 4
−max: 12
−step: 0.5
−unit: in
−setpoints: [4, 5, 6, 8, 12]
−default: 6
+label: Microsynthetic Fibers for Plastic Shrinkage Control
+type: radio
+options:
+ - "Included"
+ - "Not included"
```
−### For commercial slabs-on-ground, IBC 2024 §1907 and IRC 2024 §R506 establish prescriptive minimum thickness and fill requirements that the design shall not fall below. {note}
+### Fibrillated or monofilament microsynthetic fibers at a fraction of a pound per cubic yard hold the surface together during the first hours, while the concrete is plastic and evaporation is pulling it apart; they do nothing for drying shrinkage cracking afterward and are not a crack-control strategy, which is why they are specified as a separate decision and never in place of one. {note}
−## The slab thickness shall be held within the tolerance of ACI 117-10, verified against the trimmed subbase elevation.
+## Post-Tensioned Slabs {toc}
−```datasheet
−label: Slab thickness tolerance
−type: range
−min: -0.375
−max: 0.5
−step: 0.125
−unit: in
−setpoints: [-0.375, 0.375, 0.5]
−default: -0.375
−```
+### A post-tensioned slab shall be placed on a friction-reducing layer of two sheets of polyethylene, or the alternative layer the slab design specifies, laid over the subbase or the vapor retarder.
+### Tendon profile, spacing, and anchorage locations shall be as shown on [[drawing: the tendon layout drawings]].
+
+### A post-tensioned slab shall have no contraction joints, and its construction joints and pour strips shall be located where the tendon layout drawings show them.
+
+## Shrinkage-Compensating Slabs {toc}
+
+### A shrinkage-compensating slab shall carry the reinforcement, in the position, that ACI 223R requires for the expansion the mixture is designed to develop.
+
+### Joint spacing and the slip layer beneath a shrinkage-compensating slab shall be as ACI 223R requires and as shown on the joint layout.
+
# Joints {toc}
−## Joints are the slab's deliberate crack-control plan; a slab will crack, and the only choice is whether it cracks where designed or at random. {note}
+## A slab on ground is going to crack, and the joint layout is the choice of where. Contraction joints create planes of weakness so that the shrinkage cracks form in straight lines beneath a saw cut instead of wandering across the floor. Isolation joints separate the slab from the columns, walls, footings, and pads that would otherwise hold it still while it shrinks, so that the restraint of those elements does not crack the field. Construction joints close out each placement and are the one joint type located by the crew's production rate rather than by the shrinkage of the slab, which is why they are made to coincide with the contraction joint lines. ACI 224.3R and ACI 302.1R set out the mechanisms; the layout that applies them is drawn for each floor. {note}
−## Contraction (control) joints create planes of weakness so shrinkage cracks form straight and hidden beneath the joint. Isolation joints separate the slab from columns, walls, and footings so their restraint does not crack the field. Construction joints close out each day's placement. Joint design principles follow ACI 224.3R-95. {note}
+## Joint locations shall be as shown on [[drawing: the slab joint layout on the structural drawings]].
## Contraction Joints {toc}
−### Contraction joints shall be located so that the spacing in feet does not exceed the specified multiple of the slab thickness in inches.
+### Contraction joints shall be spaced so that the distance between joints does not exceed the multiple of the slab thickness indicated in the datasheet, measured in consistent units.
```datasheet
−label: Contraction joint spacing factor
+label: Contraction Joint Spacing as a Multiple of Slab Thickness
type: range
−min: 24
−max: 36
−step: 2
−unit: × slab thickness (in) = spacing (ft)
−setpoints: [24, 30, 36]
−default: 30
+unit: "× slab thickness"
+options:
+ min: 20
+ max: 60
+ step: 2
+constraint: max
```
−### Contraction joint panels shall be kept as close to square as practical, with the long-to-short side ratio not exceeding the specified maximum.
+### At 24 to 36 times the thickness, which is 2 to 3 ft of spacing for each inch of slab, a plain slab of ordinary shrinkage cracks at its joints and nowhere else; a mixture with a measured shrinkage limit, a fiber-reinforced slab, or a slab with a shrinkage-reducing admixture is carried to the upper end of that band or beyond it. Every foot added to the spacing is a joint removed from the floor and a foot added to the opening of the joints that remain, so a wider spacing is paid for in dowels, in filler, and in the width the filler has to bridge. {note}
+### Contraction joint panels shall have a ratio of long side to short side not exceeding the value indicated in the datasheet.
+
```datasheet
−label: Maximum panel aspect ratio
+label: Panel Aspect Ratio
type: range
−min: 1.0
−max: 1.5
−step: 0.25
−unit: long:short
+unit: "long side : short side"
+options:
+ min: 1
+ max: 1.5
+ setpoints: [1, 1.25, 1.5]
default: 1.5
+constraint: max
```
−### Long, narrow panels crack across the middle because shrinkage accumulates along the long dimension faster than the joints can relieve it. Keeping panels near-square keeps cracks at the joints. {note}
+### A long narrow panel cracks across its middle because the shrinkage along its long dimension accumulates faster than the joints at its ends can relieve it; panels kept close to square crack at their joints. {note}
−### Saw-cut contraction joints shall be cut to the specified depth as a fraction of the slab thickness to reliably induce cracking at the joint.
+### Contraction joints shall run through the corners of column isolation joints and shall align with column lines.
+### Contraction joints shall be continuous across the slab from edge to edge, or from an edge to an isolation joint, and shall not stop within a panel.
+
+### A contraction joint or a diagonal reinforcing bar shall be provided at every re-entrant corner in the slab, as the joint layout shows.
+
+### Contraction joints shall be formed by the method indicated in the datasheet.
+
```datasheet
−label: Saw-cut joint depth
+label: Contraction Joint Sawing Method
type: radio
options:
− - 1/4 of slab thickness (early-entry sawing)
− - 1/3 of slab thickness (conventional sawing)
−default: 1/4 of slab thickness (early-entry sawing)
+ - "Conventional wet-cut sawing to one-quarter of the slab thickness"
+ - "Early-entry dry-cut sawing to the depth the saw manufacturer specifies for the slab thickness"
+ - "Preformed plastic insert strip placed in the plastic concrete"
```
−### Saw-cutting shall begin as soon as the concrete will support the saw without raveling and before shrinkage cracking develops.
+### A conventional saw cuts a quarter of the thickness and has to wait until the concrete is hard enough not to ravel, which on a hot day is after the slab has already cracked somewhere else; an early-entry saw cuts a shallower joint within an hour or two of finishing, before the shrinkage stress develops, and relies on the still-weak concrete to crack beneath its shallower cut; a preformed insert pressed into the plastic concrete needs no sawing at all and leaves a joint edge that is harder to fill and more easily damaged, which keeps it to floors without hard-wheeled traffic. {note}
−### The single most common joint failure is cutting too late. Early-entry saws are used within hours of finishing precisely so the cut precedes the shrinkage crack; waiting for conventional saws often lets the slab crack first, defeating the joint. {note}
+### Contraction joints shall be cut as soon as the concrete supports the saw without raveling the cut edge, and in every case within the time after final finishing indicated in the datasheet.
−### Saw-cutting shall be completed within the specified window after final finishing, adjusted for temperature and conditions.
−
```datasheet
−label: Saw-cut timing window after finishing
+label: Time After Final Finishing Within Which Contraction Joints Are Cut
type: range
−min: 2
−max: 12
−step: 1
unit: hours
−setpoints: [2, 4, 8, 12]
−default: 4
+options:
+ min: 1
+ max: 24
+ setpoints: [1, 2, 4, 6, 8, 12, 24]
+constraint: max
```
+### Cutting too late is the single most common joint failure on a floor. Shrinkage stress builds from the moment the slab stops bleeding, and in hot or windy weather a conventional saw cannot get on the slab before the first random crack forms; the window is set against the sawing method and the weather, and the trial placement is where it is confirmed. {note}
+
+### Where a random crack forms before the contraction joints are cut, the Contractor shall notify the Engineer of Record before cutting the joints in that panel.
+
## Isolation Joints {toc}
−### Isolation joints shall be provided at all columns, walls, footings, equipment pads, and fixed penetrations to separate the slab from restraint.
+### A full-depth isolation joint shall be provided around every column, at every wall, footing, and foundation the slab abuts except where the slab edge is doweled to or bears on the foundation, around every equipment pad, pit, trench drain, and sump, and around every pipe, conduit, and duct that penetrates the slab.
−### Anything that restrains the slab while it shrinks becomes a crack origin. Columns are the classic case: without an isolation joint, cracks radiate diagonally from each column corner. Full-depth isolation lets the field move independently. {note}
+### Anything that holds the slab while it shrinks becomes the origin of a crack. Columns are the classic case: without an isolation joint a crack radiates diagonally from each column corner across the panel, and no reinforcement in the slab stops it. The joint is full depth so that nothing at the bottom of the section restrains what the top is free to do. {note}
−### A full-depth isolation joint shall be provided around every column and at every junction with a wall or footing.
+### Isolation joints shall be filled with a preformed compressible filler of the thickness indicated in the datasheet, extending the full depth of the slab.
−### Isolation joints shall be formed with preformed filler conforming to ASTM D1751 at the specified thickness.
+```datasheet
+label: Isolation Joint Filler Thickness
+type: range
+unit: in
+options:
+ min: 0.25
+ max: 1
+ setpoints: [0.25, 0.375, 0.5, 0.75, 1]
+default: 0.5
+constraint: exact
+```
+### The preformed compressible filler shall conform to [[sync/concrete-joints-and-waterstops]].
+
+### Column isolation joints shall be of the shape indicated in the datasheet.
+
```datasheet
−label: Isolation joint filler thickness
−type: select
+label: Column Isolation Joint Shape
+type: radio
options:
− - 1/4 in
− - 3/8 in
− - 1/2 in
−unit: in
−default: 1/2 in
+ - "Diamond, turned 45° to the contraction joint lines"
+ - "Circular"
+ - "Square, with the contraction joints run to its corners"
```
−### Column isolation joints shall be diamond-shaped (turned 45°) or circular so the slab can shrink away from the column on all sides.
+### A diamond turned to the joint lines puts a corner of the isolation joint on each contraction joint, so the joints meet the column and the panel has no re-entrant corner; a circular isolation joint has no corners to crack from and is the detail for a floor that stays exposed, at the cost of a formed circle; a square boxout aligned with the contraction joints is the simplest to form and works only where the joints are run to its corners, because a square with a joint arriving at the middle of a side leaves a re-entrant corner that cracks. {note}
+### Where an isolation joint is sealed, the top of the filler shall be recessed to the depth the sealant manufacturer requires.
+
## Construction Joints {toc}
−### Construction joints shall be located at the edges of each placement and shall coincide with planned contraction joints wherever practical.
+### Construction joints shall be located at the limits of each placement as the accepted joint layout plan shows, and each shall coincide with a contraction joint line.
−### Load-transfer devices shall be provided at construction joints and at contraction joints subject to hard-wheeled traffic, sized to transfer load while permitting horizontal movement.
+### Construction joint faces shall be formed straight and vertical by bulkheads furnished under [[sync/concrete-formwork]] and set true to line.
−### Across a joint carrying forklifts, the two panels must deflect together or the joint edges spall under each wheel pass. Smooth dowels or plate dowels transfer the vertical load while still letting the joint open as the slab shrinks. {note}
+### Where a placement is interrupted long enough that the concrete in place reaches initial set, the Contractor shall terminate the placement at a bulkhead on a planned joint line and shall notify the Engineer of Record.
−### Where load transfer is required, dowels shall be provided of the type and size selected below.
+## Load Transfer Across Joints {toc}
+### Where a loaded wheel crosses a joint, the two panels either deflect together or the loaded edge drops below the unloaded one, and every pass of the wheel then strikes the far edge. Hard wheels on a pallet jack or a lift truck spall an undoweled joint within months. A load-transfer device makes the two panels deflect together while still letting the joint open as the slab shrinks, which is the combination that aggregate interlock alone loses as soon as the joint opens more than a few hundredths of an inch. {note}
+
+### The joints that receive load-transfer devices shall be as indicated in the datasheet.
+
```datasheet
−label: Load-transfer device type
+label: Joints Receiving Load-Transfer Devices
type: radio
options:
− - None (no hard-wheeled traffic)
− - Smooth round dowel bars
− - Square / diamond plate dowels
−default: Smooth round dowel bars
+ - "Construction joints only"
+ - "Construction joints and the contraction joints in areas of hard-wheeled traffic"
+ - "All construction and contraction joints"
+ - "No joints"
```
+### A construction joint is a formed, full-depth separation with no aggregate interlock at all, so it is doweled on nearly every floor that carries anything on wheels; contraction joints keep their interlock until they open, which on a floor with light traffic is enough, and on a floor with hard wheels is not, so they are doweled where the traffic runs and left to interlock elsewhere; doweling every joint is the choice for a floor whose traffic pattern is not known or will change; no devices at all suits a slab that carries foot traffic and pneumatic tires only. {note}
+
+### The load-transfer device shall be as indicated in the datasheet.
+
```datasheet
−label: Smooth dowel bar diameter
−type: select
+label: Load-Transfer Device
+type: radio
options:
− - 3/4 in
− - 1 in
− - 1-1/4 in
− - 1-1/2 in
−unit: in
−default: 1 in
+ - "Smooth round dowel bars"
+ - "Plate dowels, square or diamond"
+ - "Tapered plate dowels"
+ - "Keyed joint"
+ - "Aggregate interlock only, without a device"
```
−## Joint Filling {toc}
+### A smooth round dowel is the least expensive device and the one most sensitive to alignment, because a bar skewed in the joint locks it as the slab shrinks; a square or diamond plate dowel in a sleeve lets the joint move both along and across the bar, so it tolerates the misalignment that locks a round bar and can be used at a joint where panels shrink in two directions; a tapered plate keeps its bearing tight as the joint opens, which holds the deflection down at a joint that will open wide; a keyed joint transfers load through the concrete key itself and loses that transfer as soon as the joint opens, so it serves only a lightly loaded floor; aggregate interlock without a device serves where no hard wheel will cross the joint. {note}
−### Whether and how joints are filled depends on the traffic, and leaving joints unfilled under hard wheels guarantees edge spalling. {note}
+### Dowel diameter shall be as indicated in the datasheet.
−### Contraction joints in a space with hard-wheeled traffic must be filled with a semi-rigid filler that supports the joint edges; leaving them open lets the loaded wheels chip the arrises. In light-traffic spaces, an elastomeric sealant or even an open joint may be acceptable. The filler must not be installed until the slab has done most of its drying shrinkage, or it will be pulled apart as the joint opens. {note}
+```datasheet
+label: Dowel Diameter
+type: range
+unit: in
+drawing_ref: "the slab joint details on the structural drawings"
+options:
+ min: 0.5
+ max: 1.5
+ setpoints: [0.5, 0.625, 0.75, 0.875, 1, 1.25, 1.5]
+default: deferred
+constraint: exact
+```
−### Contraction joints in areas subject to hard-wheeled traffic shall be filled with a semi-rigid epoxy or polyurea filler that supports the joint edges full depth of the saw cut.
+### Dowel length shall be as indicated in the datasheet.
−### Joints not subject to hard-wheeled traffic shall be filled with an elastomeric sealant conforming to ASTM C920 or left open as specified.
−
```datasheet
−label: Joint filling treatment
−type: radio
+label: Dowel Length
+type: range
+unit: in
+drawing_ref: "the slab joint details on the structural drawings"
options:
− - Semi-rigid epoxy / polyurea filler (hard-wheeled traffic)
− - Elastomeric sealant (ASTM C920)
− - Leave open
−default: Semi-rigid epoxy / polyurea filler (hard-wheeled traffic)
+ min: 12
+ max: 24
+ step: 1
+default: deferred
+constraint: exact
```
−### Joint filling shall be deferred until the slab has undergone the specified minimum drying period so the joint opening has substantially stabilized.
+### Dowel spacing along the joint shall be as indicated in the datasheet.
```datasheet
−label: Minimum cure before joint filling
+label: Dowel Spacing Along the Joint
type: range
−min: 28
−max: 90
−step: 7
−unit: days
−setpoints: [28, 60, 90]
−default: 90
+unit: in
+drawing_ref: "the slab joint details on the structural drawings"
+options:
+ min: 12
+ max: 24
+ step: 1
+default: deferred
+constraint: exact
```
−# Curing {toc}
+### Smooth round dowels shall be plain round bars conforming to ASTM A36/A36M or ASTM A615/A615M, with sawn ends free of burrs.
−## Curing keeps water in the concrete during the critical early days when surface strength and abrasion resistance are developing, and inadequate curing is a leading cause of dusting and surface failures. {note}
+### One half of the length of each smooth dowel shall be coated or sleeved so that it does not bond to the concrete.
−## A slab that dries too fast at the surface ends up with a weak, dusting wear layer no matter how strong the body of the concrete is. The curing method must also be compatible with the planned floor covering — a wax-based compound under adhesive flooring can cause bond failure. {note}
+### Plate dowels shall be installed in the sleeves or pockets the manufacturer furnishes, so that the plate can move in the plane of the slab as the joint opens.
−## Curing shall begin immediately after final finishing and shall continue for the specified minimum duration.
+### Dowels shall be held parallel to the slab surface and perpendicular to the joint, within the alignment tolerance of ACI 117, by baskets staked to the subbase or by the bulkhead form.
−```datasheet
−label: Minimum curing duration
−type: range
−min: 3
−max: 14
−step: 1
−unit: days
−setpoints: [3, 7, 14]
−default: 7
−```
+### Dowels shall not be inserted into fresh concrete after placement.
−## The curing method shall be selected for compatibility with the finished floor covering and the placement conditions.
+### The shipping wires that hold a dowel basket square shall be cut before concrete is placed.
+### Where a keyed joint is indicated, the key shall be formed to the profile the joint details show, and a keyed joint shall not be used where hard-wheeled vehicles will cross it unless the Engineer of Record directs otherwise in writing.
+
+## Joint Filling and Sealing {toc}
+
+### Whether a joint is filled depends on what crosses it. A hard wheel striking an unfilled saw cut chips the joint edge on every pass; a semi-rigid filler supports those edges from inside the cut and is the only treatment that protects them. A joint that carries no hard wheels can be sealed to keep water and debris out of it or simply left open. The filler that supports an edge is also the one that cannot stretch, so it has to go in after the slab has done most of its shrinking, or the joint opens and splits it. {note}
+
+### Contraction and construction joints shall receive the treatment indicated in the datasheet.
+
```datasheet
−label: Curing method
+label: Contraction and Construction Joint Treatment
type: radio
options:
− - Wet cure (continuous moisture, burlap/poly)
− - Curing compound, ASTM C309 (resin or wax base)
− - Curing/sealing compound, ASTM C1315 (resin base)
−default: Wet cure (continuous moisture, burlap/poly)
+ - "Semi-rigid epoxy or polyurea filler, full depth of the saw cut"
+ - "Elastomeric sealant over a backer rod"
+ - "Left open and unfilled"
```
−## Where slabs will receive adhesive-applied flooring, a resin-based ASTM C1315 compound shall be used or the compound shall be fully removed before flooring installation. {note}
+### A semi-rigid filler supports the joint edge against wheel impact and is installed full depth without a backer rod, at the cost of a product that cannot follow a joint that keeps opening; an elastomeric sealant follows joint movement and keeps the joint clean and watertight but is soft and offers the edge no support; an open joint costs nothing and collects whatever falls into it, which suits a floor that is covered, bare under foot traffic only, or scheduled for a later finish that fills the joints itself. {note}
−## Where early solar heat gain or surface temperature is a concern, a white-pigmented (Type 2) curing compound shall be specified to reflect heat.
+### Where hard-wheeled vehicles will cross a joint, that joint shall receive a semi-rigid filler unless the datasheet indicates otherwise.
−## In hot, dry, or windy conditions, an evaporation retarder shall be applied to the bleeding surface to prevent plastic shrinkage cracking before final finishing.
+### Semi-rigid filler shall be a two-component epoxy or polyurea with a Shore A hardness of not less than 80 when tested in accordance with ASTM D2240, installed full depth of the saw cut without a backer rod, overfilled, and shaved flush with the floor surface after cure.
−## Plastic shrinkage cracks form when surface water evaporates faster than bleed water rises, which happens quickly under sun and wind. An evaporation retarder is a temporary film that buys the finishers time; it is not a curing compound and does not replace curing. {note}
+### Elastomeric sealant shall conform to ASTM C920 and shall be installed over a backer rod to the width-to-depth ratio the sealant manufacturer requires.
−# Surface Tolerances {toc}
+### Joints shall not be filled until the slab has reached the age indicated in the datasheet.
−## Floor flatness and levelness are specified with F-numbers, but the numbers are meaningless until the surface class is identified, because conventional and defined-traffic floors are measured and built differently. {note}
+```datasheet
+label: Slab Age Before Joints Are Filled
+type: range
+unit: days
+options:
+ min: 28
+ max: 180
+ setpoints: [28, 60, 90, 120, 180]
+constraint: min
+```
−## FF (flatness) governs bumpiness; FL (levelness) governs tilt. A conventional random-traffic floor is specified with overall FF/FL values per ASTM E1155. A defined-traffic (DT) floor for narrow-aisle, high-rack warehouses is measured directionally along the wheel paths and drives the screeding method and pour sequence. Specifying F-numbers without the class leaves the contractor unable to plan the placement. {note}
+### Most of a slab's drying shrinkage occurs in its first months, and a joint filled early is pulled apart as the joint continues to open; delaying the filling as long as the construction schedule permits leaves less movement for the filler to absorb, at the cost of a floor whose joints stay unprotected until the filler goes in. {note}
−## The floor surface class shall be identified before specifying F-number tolerances.
+### Immediately before filling, joints shall be cleaned of curing compound, laitance, and debris by dry sawing or sandblasting and shall be vacuumed.
+### Spalled joint edges shall be repaired with the filler manufacturer's repair material before the joint is filled.
+
+# Floor Flatness and Levelness {toc}
+
+## Floor flatness and levelness are specified by F-numbers because a straightedge cannot measure a floor. FF describes bumpiness over short distances, the waviness a lift truck mast amplifies into sway; FL describes tilt over longer distances, the slope that leaves a rack leg short of the floor. Both are measured by the procedure of ASTM E1155 as an overall value for the whole floor and a minimum local value for each test section, because a floor can average well and still carry a hump that stops a pallet jack. A defined-traffic floor, where very narrow aisle trucks run on fixed wheel paths between high racks, is measured differently: along the wheel paths themselves, by F-min numbers that bound the change in elevation across and along each path. {note}
+
+## The floor surface class shall be as indicated in the datasheet.
+
```datasheet
−label: Floor surface class
+label: Floor Surface Class
type: radio
options:
− - Conventional (random traffic), ASTM E1155 FF/FL
− - Defined-traffic (narrow-aisle), directional tolerance
−default: Conventional (random traffic), ASTM E1155 FF/FL
+ - "Random-traffic floor, measured by overall and local F-numbers per ASTM E1155"
+ - "Defined-traffic floor, measured along the wheel paths by F-min numbers"
+default: "Random-traffic floor, measured by overall and local F-numbers per ASTM E1155"
```
−## For conventional floors, the specified overall flatness (FF) and levelness (FL) shall be achieved and verified per ASTM E1155.
+## The overall flatness of a random-traffic floor shall be not less than the FF value indicated in the datasheet.
```datasheet
−label: Specified overall flatness FF
+label: Overall Flatness FF
type: range
−min: 20
−max: 50
−step: 5
unit: FF
−setpoints: [20, 25, 35, 50]
−default: 35
+options:
+ min: 15
+ max: 100
+ setpoints: [15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 100]
+constraint: min
```
+## The overall levelness of a random-traffic floor shall be not less than the FL value indicated in the datasheet.
+
```datasheet
−label: Specified overall levelness FL
+label: Overall Levelness FL
type: range
−min: 15
−max: 40
−step: 5
unit: FL
−setpoints: [15, 20, 25]
−default: 25
+options:
+ min: 10
+ max: 60
+ setpoints: [10, 15, 20, 25, 30, 35, 40, 50, 60]
+constraint: min
```
−## The F-number survey shall be performed within 72 hours of slab placement, before shoring or curling can alter the result, per ASTM E1155. {note}
+## The local flatness of each test section shall be not less than the FF value indicated in the datasheet.
−## Defined-traffic floors shall meet the directional flatness and levelness limits along the defined wheel paths as scheduled.
+```datasheet
+label: Local Flatness FF
+type: range
+unit: FF
+options:
+ min: 10
+ max: 70
+ setpoints: [10, 13, 15, 17, 20, 24, 25, 30, 35, 40, 50, 70]
+constraint: min
+```
−## The defined-traffic limits and aisle locations are layout-specific and cannot be reduced to a single field; they are coordinated on the floor plan. Aisle and wheel-path locations are indicated [[drawing: defined-traffic aisle layout]]. {note}
+## The local levelness of each test section shall be not less than the FL value indicated in the datasheet.
−# Installation {toc}
+```datasheet
+label: Local Levelness FL
+type: range
+unit: FL
+options:
+ min: 7
+ max: 40
+ setpoints: [7, 10, 12, 13, 15, 17, 20, 25, 30, 35, 40]
+constraint: min
+```
−## The slab shall be placed, struck off, and finished in a continuous operation per section, working from the established screed lines and joints.
+## The F-number ladder tracks what runs on the floor. A slab that will be covered by a thick finish or that carries foot traffic only is built to the low end; an office or retail floor under a thin covering needs the flatness that keeps a resilient tile from telegraphing every bump; a warehouse with lift trucks in open aisles needs the flatness that keeps the mast from swaying and the levelness that keeps the racks plumb; and a floor that stays exposed as the finished surface is built to the number its owner can see. Local values are set at roughly two-thirds of the overall values, so that an individual section can be rougher than the floor's average without being bad enough to notice. Each step up the ladder is paid for in the strike-off method, in narrower placement strips, in the crew's skill, and in the number of sections that fail and are ground. {note}
−## Concrete shall not be placed when ambient or material temperatures fall outside the specified range without approved cold- or hot-weather protection.
+## The F-min tolerance of a defined-traffic floor shall be not less than the value indicated in the datasheet, applied along and across each wheel path.
```datasheet
−label: Allowable concrete placement temperature
+label: Defined-Traffic F-min
type: range
−min: 40
−max: 90
−step: 5
−unit: °F
−setpoints: [40, 50, 80, 90]
−default: 80
+unit: F-min
+options:
+ min: 50
+ max: 150
+ setpoints: [50, 60, 75, 100, 125, 150]
+constraint: min
```
−## Water shall not be added to the surface to aid finishing, as it weakens the wear surface and causes dusting and scaling.
+## The aisle and wheel-path locations of a defined-traffic floor shall be as shown on [[drawing: the defined-traffic aisle layout]].
−## Finishing operations shall not begin while bleed water is present on the surface.
+## Floor flatness and levelness shall be measured in accordance with ASTM E1155 within 72 hours after the completion of finishing of each placement and before the placement is loaded.
−## Troweling bleed water back into the surface traps it under a sealed skin and is a direct cause of blistering and delamination. Finishers must wait for the sheen to leave before floating and troweling. {note}
+## Measured later than 72 hours, the survey records curling at the joints rather than the surface the finishers produced, and a slab that was within tolerance when it was finished can then fail a test that no finishing could have passed; measuring early fixes responsibility for the as-finished surface on the finishing crew and for later curling on the mixture and the curing. {note}
−## The surface finish shall be the type required by the floor's service and any subsequent covering.
+## Levelness shall not be applied to a slab placed on a designed slope, and such areas shall be evaluated for flatness only and for conformance to the slope shown on [[drawing: the floor drainage plan]].
+## Test sections outside the specified tolerances shall be corrected by grinding, by removal and replacement, or by another method the Engineer of Record accepts in writing, at the Contractor's cost.
+
+# Placement and Finishing Coordination {toc}
+
+## Pre-Placement Verification {toc}
+
+### Immediately before concrete is placed in each slab area, the Contractor shall verify and record the items indicated in the datasheet.
+
```datasheet
−label: Surface finish
−type: radio
+label: Verification Required Before Slab Concrete Is Placed
+type: checkbox
options:
− - Steel-troweled (hard, dense)
− - Float finish
− - Broom finish (exterior / slip resistance)
−default: Steel-troweled (hard, dense)
+ - "Subbase surface is surveyed, accepted, and within tolerance"
+ - "Subbase or subgrade surface is damp with no free water, mud, ice, or frozen material"
+ - "Vapor retarder is complete, lapped, sealed at penetrations, and repaired"
+ - "Reinforcement or fiber dosage matches the placing drawings and the mixture submittal"
+ - "Reinforcement is at its specified depth on supports at the specified spacing"
+ - "Dowels are aligned and baskets are staked with shipping wires cut"
+ - "Isolation joint filler is in place at every column, wall, pad, pit, and penetration"
+ - "Edge forms and bulkheads are set to line and grade and braced"
+ - "Embedded items, sleeves, and anchor rods are set and secured"
+ - "Saw, blades, and crew are on site and the sawing window is agreed"
+ - "Curing materials are on site in the quantity the placement needs"
+ - "Testing agency technician is present at the point of discharge"
+default:
+ - "Subbase surface is surveyed, accepted, and within tolerance"
+ - "Subbase or subgrade surface is damp with no free water, mud, ice, or frozen material"
+ - "Vapor retarder is complete, lapped, sealed at penetrations, and repaired"
+ - "Reinforcement is at its specified depth on supports at the specified spacing"
+ - "Dowels are aligned and baskets are staked with shipping wires cut"
+ - "Isolation joint filler is in place at every column, wall, pad, pit, and penetration"
+ - "Edge forms and bulkheads are set to line and grade and braced"
+ - "Saw, blades, and crew are on site and the sawing window is agreed"
+ - "Curing materials are on site in the quantity the placement needs"
+constraint: all_of
```
−## Exterior slabs, aprons, and dock pads shall be sloped to drain as indicated and shall receive a broom finish for slip resistance. {note}
+### Concrete shall not be placed until every deficiency found in the verification has been corrected.
−## Exterior slab drainage slopes and high/low points are indicated [[drawing: exterior slab drainage]]. {note}
+### The verification record shall identify the placement, the date, and the person who performed it.
−# Field Quality Control {toc}
+## Placement Sequence and Strike-Off {toc}
−## Acceptance of the finished slab rests on documented field results, not visual inspection alone, because the defects that matter most are dimensional and below the surface. {note}
+### Slab concrete shall be placed in the sequence, within the limits, and by the strike-off method the accepted placement plan states.
−## The testing agency shall record slump, air content, temperature, and unit weight for each sampled load.
+### Each panel bounded by construction joints shall be placed continuously, without a cold joint within the panel.
−## Compressive strength cylinders shall be cast, cured, and tested per the project specifications, and results below the specified strength shall be evaluated per ACI 360R-10.
+### Equipment and personnel routes across the vapor retarder and the placed reinforcement shall be limited to those the placement plan shows, and reinforcement displaced by traffic shall be restored to position before the concrete reaches it.
−## The finished slab shall be inspected for cracking, and any crack exceeding the specified width shall be evaluated and repaired as directed.
+### The strike-off method is what the F-numbers are bought with. A laser-guided screed or a vibrating truss screed riding on set forms produces a flat strip; hand strike-off from wet screeds produces whatever the screed-setter's eye produces. Long narrow placement strips with the screed riding on hard edge forms are how a tight tolerance is reached, and a wide placement finished from the middle is how a loose one is. {note}
+## Finishing and Curing {toc}
+
+### Finishing and curing of the slab shall be performed under [[sync/concrete-curing-and-finishing]], with the finish and the curing method that standard assigns to the scheduled floor covering.
+
+### Water shall not be added to the surface to aid finishing.
+
+### Finishing operations shall not begin while bleed water is present on the surface.
+
+### Troweling bleed water back into the surface traps it under a dense skin, and the blisters and delaminations that result appear weeks later as the trapped water tries to leave. The finishers' waiting for the sheen to go is the step most often skipped on a cold day and most often regretted. {note}
+
+## Protection and Loading {toc}
+
+### Rubber-tired construction equipment shall not operate on the slab, and no material shall be stockpiled on it, until the slab concrete has attained the fraction of its specified compressive strength indicated in the datasheet, demonstrated by field-cured specimens from that placement or by the maturity method.
+
```datasheet
−label: Maximum acceptable crack width before evaluation
+label: Fraction of Specified Compressive Strength Before Construction Traffic
type: range
−min: 0.01
−max: 0.04
−step: 0.005
+unit: "%"
+options:
+ min: 50
+ max: 100
+ setpoints: [50, 60, 70, 75, 80, 100]
+constraint: min
+```
+
+### Early loading drives a wheel across joints that have not yet been cut or filled and over concrete that has not reached the strength the dowels bear on, and the joint edges it breaks are the ones the finished floor will show for its life. {note}
+
+### Saw cuts shall be kept free of debris, and shall be covered or taped where other trades work over the slab, until the joints are filled.
+
+### The slab surface shall be protected from staining, impact, point loads, and the dragging of steel and equipment until the slab work is accepted.
+
+# Field Quality Control {toc}
+
+## The thickness of each placement shall be verified by comparing the subbase surface survey with the finished floor survey at the same grid points.
+
+## Where the survey comparison indicates a thickness below the tolerance of ACI 117, the Engineer of Record shall direct cores at the locations and number the Engineer of Record selects, taken and tested at the Contractor's cost.
+
+## Random cracks wider than the width indicated in the datasheet shall be reported to the Engineer of Record, who shall direct their evaluation and repair under [[sync/concrete-repair-and-restoration]].
+
+```datasheet
+label: Random Crack Width Above Which the Crack Is Reported
+type: range
unit: in
−default: 0.02
+options:
+ min: 0.004
+ max: 0.03
+ setpoints: [0.004, 0.008, 0.012, 0.016, 0.02, 0.03]
+constraint: max
```
+## A hairline crack in a bare warehouse floor is a cosmetic record of where the shrinkage went; the same crack beneath a resilient tile or an epoxy coating telegraphs through the finish and keeps moving under it, which is why the width at which a crack is reported is set by what the floor will carry rather than by the structural significance of the crack, which for a slab on ground is usually nil. {note}
+
+## The cost of evaluating and repairing a random crack attributable to late sawing, inadequate curing, premature loading, or a defect in the subbase placed under this standard shall be borne by the Contractor, and the Engineer of Record shall make the initial determination of the cause.
+
+## Joints shall be inspected for spalling, raveling, and curling before they are filled, and the inspection shall be recorded in the joint filling record.
+
# Delivery, Storage, and Handling {toc}
−## Reinforcement and welded wire reinforcement shall be stored off the ground and protected from contaminants that impair bond.
+## Reinforcing steel for the slab shall be delivered, stored, and handled under [[sync/concrete-reinforcement]].
−## Vapor retarder material shall be stored protected from sunlight and physical damage until installation.
+## Fibers shall be delivered in the manufacturer's packaging in the quantity per package the batching procedure relies on, and shall be stored dry until batched.
−## Joint filler, sealant, and curing materials shall be stored within the manufacturer's specified temperature range and shall not be used past their shelf life. {note}
+## Dowels, plate dowels, baskets, and sleeves shall be stored off the ground, with debonding coatings intact and free of rust that reduces the section or roughens the sliding surface.
+## Joint filler and sealant shall be stored within the temperature limits the manufacturer publishes and shall not be used past the published shelf life.
+
+## Preformed compressible filler shall be stored flat and protected from moisture and crushing.
+
# Warranty {toc}
−## The Contractor shall warrant the slab-on-grade against defective materials and workmanship for the specified period from substantial completion.
+## The Contractor shall warrant the slab work against defects in materials and workmanship for the period indicated in the datasheet, running from the date of substantial completion.
```datasheet
−label: Workmanship warranty period
+label: Installation Warranty Period
type: range
−min: 1
−max: 5
−step: 1
unit: years
+options:
+ min: 1
+ max: 10
+ setpoints: [1, 2, 3, 5, 10]
default: 1
+constraint: min
```
−## Cracking, spalling, scaling, or dusting attributable to defective materials or workmanship within the warranty period shall be repaired at no cost to the Owner.
+## The warranty shall cover random cracking wider than the reporting width, spalling or raveling of joint edges, separation, splitting, or debonding of joint filler and sealant, curling that lifts a joint edge beyond the local levelness tolerance, and settlement of the slab attributable to the subbase placed under this standard.
−# Spare Parts {toc}
+## The warranty shall not cover damage caused by loads exceeding the design basis recorded on the contract documents, by vehicle or equipment impact, by settlement of a subgrade prepared under a scope other than the Contractor's, or by chemical attack the slab was not designed to resist.
−## The Contractor shall deliver to the Owner the specified quantity of joint filler and sealant matching that installed, for future joint maintenance.
+## Whether the Contractor returns within the warranty period to refill joints shall be as indicated in the datasheet.
```datasheet
−label: Spare joint filler / sealant
−type: range
−min: 0
−max: 10
−step: 1
−unit: gal
−default: 2
+label: Joint Refill Visit Within the Warranty Period
+type: radio
+options:
+ - "Required once, after the first year of the warranty period"
+ - "Not required"
```
+
+## Joint filler installed at an age of a few months is installed into a joint that is still opening, and some separation from the joint face is the expected result rather than a defect; a scheduled return to refill the separated joints after the first year costs a day of work and leaves the floor with filler that is bonded to the joint it will serve, where leaving it to the warranty claim process costs the same work plus the dispute over whether the separation is a defect. {note}
+
+## Where a warranty repair is performed, the repaired work shall be warranted for the full original warranty period running from the date of the repair, or for the remainder of the original period, whichever ends later.
+
+## The Contractor shall bear the cost of a warranty repair and of removing and reinstalling floor covering, racks, and equipment to gain access for it, except where the Owner's own forces caused the condition repaired.