+---
+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.
+---
+
+# 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}
+
+## 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}
+
+## 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}
+
+## 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 following are outside this standard and are governed elsewhere. {note}
+
+- 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.
+
+## Slab classification {toc}
+
+### The slab classification shall be selected to match the structural demand and crack-control strategy of the application. {note}
+
+### 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}
+
+```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
+```
+
+### 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.
+
+## Where referenced standards 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 |
+| 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 |
+
+# Submittals {toc}
+
+## Action Submittals {toc}
+
+### The Contractor shall submit the following action items for review before placing concrete:
+
+- 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.
+
+```datasheet
+label: Action submittals
+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
+```
+
+## Informational Submittals {toc}
+
+### The Contractor shall submit the following informational items:
+
+- 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.
+
+```datasheet
+label: Informational submittals
+type: checkbox
+options:
+ - Compaction test reports
+ - Aggregate gradation reports
+ - Concrete delivery tickets
+ - Field test reports (slump, air, strength)
+```
+
+## Closeout Submittals {toc}
+
+### The Contractor shall submit the following closeout items at substantial completion:
+
+- 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.
+
+```datasheet
+label: Closeout submittals
+type: checkbox
+options:
+ - FF/FL survey reports
+ - As-built joint layout
+ - Moisture test results
+```
+
+# 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}
+
+## 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}
+
+## The Contractor shall hold a pre-placement conference with the Engineer of Record, testing agency, and finishing crew before the first placement.
+
+## The Contractor shall not place concrete on a subgrade or subbase that has not passed compaction testing.
+
+## The Contractor shall not place concrete on frozen, saturated, or unstable subgrade.
+
+## Subgrade and subbase compaction shall be field-tested at the frequency specified, with each lift verified before the next is placed.
+
+```datasheet
+label: Compaction test frequency
+type: select
+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
+```
+
+## 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.
+
+## The testing agency shall verify slump, air content, and concrete temperature on each load sampled.
+
+# Environmental and Service Conditions {toc}
+
+## 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}
+
+## 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}
+
+## The design loads imposed on the slab shall be defined and the slab designed to resist them per ACI 360R-10.
+
+```datasheet
+label: Governing service load type
+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
+```
+
+```datasheet
+label: Design uniform live load
+type: range
+min: 100
+max: 1000
+step: 50
+unit: psf
+default: 250
+```
+
+## The subgrade modulus of subgrade reaction (k-value) used in design shall be established by geotechnical evaluation of the prepared subgrade. {note}
+
+## 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}
+
+```datasheet
+label: Design modulus of subgrade reaction (k)
+type: range
+min: 50
+max: 400
+step: 25
+unit: pci
+default: 150
+```
+
+## Where the slab will receive moisture-sensitive flooring, the design shall account for under-slab moisture control through the vapor retarder and curing method. {note}
+
+# Subgrade and Subbase {toc}
+
+## 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
+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)
+```
+
+## The subgrade moisture content at compaction shall be maintained within the range specified relative to optimum.
+
+```datasheet
+label: Compaction moisture tolerance
+type: range
+min: -3
+max: 3
+step: 1
+unit: % of optimum
+setpoints: [-2, 0, 2]
+default: 0
+```
+
+## Soft, yielding, or organic material encountered in the subgrade shall be removed and replaced with approved engineered fill compacted to the specified density.
+
+## Engineered fill shall be placed in lifts not exceeding the specified maximum loose thickness and compacted before the next lift is placed.
+
+```datasheet
+label: Maximum fill lift thickness (loose)
+type: range
+min: 6
+max: 12
+step: 2
+unit: in
+default: 8
+```
+
+## 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}
+
+## 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 granular subbase shall be provided where specified, of the type and thickness selected below.
+
+```datasheet
+label: Subbase type
+type: radio
+options:
+ - None (slab on prepared subgrade)
+ - Crushed stone / crushed gravel
+ - Lean concrete base (LCB)
+default: Crushed stone / crushed gravel
+```
+
+```datasheet
+label: Granular subbase thickness
+type: range
+min: 4
+max: 12
+step: 2
+unit: in
+default: 4
+```
+
+## The subbase shall be compacted and trimmed to the specified elevation tolerance to control slab thickness. {note}
+
+## 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}
+
+## The compacted subbase surface shall be maintained within the specified elevation tolerance before vapor retarder placement.
+
+```datasheet
+label: Subbase surface elevation tolerance
+type: range
+min: 0
+max: 1
+step: 0.25
+unit: in
+setpoints: [0.5, 0.75]
+default: 0.75
+```
+
+# Vapor Retarder {toc}
+
+## The vapor retarder placement plane is a recurring source of RFIs and flooring failures, so this standard states the placement position explicitly. {note}
+
+## 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}
+
+## 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.
+
+```datasheet
+label: Vapor retarder placement plane
+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)
+```
+
+## The vapor retarder class shall be selected per ASTM E1745 to suit the floor covering and moisture sensitivity of the space.
+
+```datasheet
+label: Vapor retarder class (ASTM E1745)
+type: radio
+options:
+ - Class A
+ - Class B
+ - Class C
+default: Class A
+```
+
+## The vapor retarder shall be installed per ASTM E1643, with laps, seams, and penetration sealing as required by [[sync/vapor-retarders]].
+
+## Vapor retarder penetrations for pipes, conduit sleeves, and column anchors shall be sealed so the membrane remains continuous. {note}
+
+## 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}
+
+## Every penetration through the vapor retarder shall be sealed to maintain continuity of the moisture barrier.
+
+# Concrete {toc}
+
+## 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}
+
+## 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}
+
+## The concrete compressive strength at 28 days shall be not less than the specified value.
+
+```datasheet
+label: Specified compressive strength (f'c) at 28 days
+type: range
+min: 3000
+max: 5000
+step: 500
+unit: psi
+default: 4000
+```
+
+## The water-cementitious materials ratio shall not exceed the specified maximum.
+
+```datasheet
+label: Maximum water-cementitious materials ratio
+type: range
+min: 0.40
+max: 0.55
+step: 0.01
+unit: w/cm
+setpoints: [0.45, 0.50]
+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
+```
+
+## Concrete aggregates shall conform to ASTM C33 for grading and quality.
+
+## The slump at the point of placement shall be within the specified range, measured after any permitted water or admixture addition.
+
+```datasheet
+label: Slump at point of placement
+type: range
+min: 3
+max: 6
+step: 0.5
+unit: in
+setpoints: [4, 5]
+default: 5
+```
+
+## Supplementary cementitious materials may be used within the proportions specified to reduce permeability and heat of hydration. {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}
+
+```datasheet
+label: Maximum SCM replacement (fly ash and/or slag)
+type: range
+min: 0
+max: 50
+step: 5
+unit: % of cementitious
+default: 25
+```
+
+## A shrinkage-reducing admixture should be specified for large jointless placements or floors with tight crack-width limits. {note}
+
+# Reinforcement and Fiber {toc}
+
+## 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}
+
+## 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}
+
+## Where conventional reinforcement is specified, it shall be welded wire reinforcement conforming to ASTM A1064 or deformed bars as scheduled.
+
+```datasheet
+label: Conventional reinforcement type
+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)
+```
+
+## Welded wire reinforcement shall be supported on chairs at the specified height within the slab so it is positioned, not left on the subgrade.
+
+```datasheet
+label: Reinforcement position from top of slab
+type: range
+min: 1.5
+max: 3
+step: 0.5
+unit: in
+default: 2
+```
+
+### 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}
+
+## Where steel fiber reinforcement is specified, the dosage shall be not less than the specified value, uniformly distributed throughout the mix.
+
+```datasheet
+label: Steel fiber dosage
+type: range
+min: 15
+max: 60
+step: 5
+unit: lb/cy
+default: 33
+```
+
+## Where synthetic macro-fiber reinforcement is specified, the dosage shall be not less than the specified value.
+
+```datasheet
+label: Synthetic macro-fiber dosage
+type: range
+min: 3
+max: 12
+step: 0.5
+unit: lb/cy
+default: 5
+```
+
+## Fibers shall be charged and mixed per the manufacturer's procedure so that balling is avoided and distribution is uniform.
+
+## 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. {note}
+
+# Slab Thickness {toc}
+
+## 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}
+
+## 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}
+
+## 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: [5, 6, 8]
+default: 6
+```
+
+### 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}
+
+## The slab thickness shall be held within the tolerance of ACI 117-10, verified against the trimmed subbase elevation.
+
+```datasheet
+label: Slab thickness tolerance
+type: range
+min: -0.375
+max: 0.5
+step: 0.125
+unit: in
+setpoints: [-0.375, 0.375]
+default: -0.375
+```
+
+# 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}
+
+## 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}
+
+## 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.
+
+```datasheet
+label: Contraction joint spacing factor
+type: range
+min: 24
+max: 36
+step: 2
+unit: × slab thickness (in) = spacing (ft)
+setpoints: [24, 30, 36]
+default: 30
+```
+
+### Contraction joint panels shall be kept as close to square as practical, with the long-to-short side ratio not exceeding the specified maximum. {note}
+
+### 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}
+
+```datasheet
+label: Maximum panel aspect ratio
+type: range
+min: 1.0
+max: 1.5
+step: 0.25
+unit: long:short
+default: 1.5
+```
+
+### 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.
+
+```datasheet
+label: Saw-cut joint depth
+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)
+```
+
+### Saw-cutting shall begin as soon as the concrete will support the saw without raveling and before shrinkage cracking develops. {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}
+
+### 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
+type: range
+min: 2
+max: 12
+step: 1
+unit: hours
+setpoints: [4, 8]
+default: 6
+```
+
+## Isolation Joints {toc}
+
+### Isolation joints shall be provided at all columns, walls, footings, equipment pads, and fixed penetrations to separate the slab from restraint. {note}
+
+### 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}
+
+### A full-depth isolation joint shall be provided around every column and at every junction with a wall or footing.
+
+### Isolation joints shall be formed with preformed filler conforming to ASTM D1751 at the specified thickness.
+
+```datasheet
+label: Isolation joint filler thickness
+type: select
+options:
+ - 1/4 in
+ - 3/8 in
+ - 1/2 in
+unit: in
+default: 1/2 in
+```
+
+### Column isolation joints shall be diamond-shaped (turned 45°) or circular so the slab can shrink away from the column on all sides. {note}
+
+## Construction Joints {toc}
+
+### Construction joints shall be located at the edges of each placement and shall coincide with planned contraction joints wherever practical.
+
+### 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. {note}
+
+### 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 load transfer is required, dowels shall be provided of the type and size selected below.
+
+```datasheet
+label: Load-transfer device type
+type: radio
+options:
+ - None (no hard-wheeled traffic)
+ - Smooth round dowel bars
+ - Square / diamond plate dowels
+default: Smooth round dowel bars
+```
+
+```datasheet
+label: Smooth dowel bar diameter
+type: select
+options:
+ - 3/4 in
+ - 1 in
+ - 1-1/4 in
+ - 1-1/2 in
+unit: in
+default: 1 in
+```
+
+## Joint Filling {toc}
+
+### Whether and how joints are filled depends on the traffic, and leaving joints unfilled under hard wheels guarantees edge spalling. {note}
+
+### 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}
+
+### 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.
+
+### 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
+options:
+ - Semi-rigid epoxy / polyurea filler (hard-wheeled traffic)
+ - Elastomeric sealant (ASTM C920)
+ - Leave open
+default: Semi-rigid epoxy / polyurea filler (hard-wheeled traffic)
+```
+
+### Joint filling shall be deferred until the slab has undergone the specified minimum drying period so the joint opening has substantially stabilized.
+
+```datasheet
+label: Minimum cure before joint filling
+type: range
+min: 28
+max: 90
+step: 7
+unit: days
+setpoints: [28, 60, 90]
+default: 90
+```
+
+# Curing {toc}
+
+## 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}
+
+## 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}
+
+## Curing shall begin immediately after final finishing and shall continue for the specified minimum duration.
+
+```datasheet
+label: Minimum curing duration
+type: range
+min: 3
+max: 14
+step: 1
+unit: days
+setpoints: [3, 7]
+default: 7
+```
+
+## The curing method shall be selected for compatibility with the finished floor covering and the placement conditions.
+
+```datasheet
+label: Curing method
+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)
+```
+
+## 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}
+
+## Where early solar heat gain or surface temperature is a concern, a white-pigmented (Type 2) curing compound shall be specified to reflect heat.
+
+## In hot, dry, or windy conditions, an evaporation retarder shall be applied to the bleeding surface to prevent plastic shrinkage cracking before final finishing. {note}
+
+## 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}
+
+# Surface Tolerances {toc}
+
+## 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}
+
+## 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}
+
+## The floor surface class shall be identified before specifying F-number tolerances.
+
+```datasheet
+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
+```
+
+## For conventional floors, the specified overall flatness (FF) and levelness (FL) shall be achieved and verified per ASTM E1155.
+
+```datasheet
+label: Specified overall flatness FF
+type: range
+min: 20
+max: 50
+step: 5
+unit: FF
+setpoints: [25, 35]
+default: 35
+```
+
+```datasheet
+label: Specified overall levelness FL
+type: range
+min: 15
+max: 40
+step: 5
+unit: FL
+setpoints: [20, 25]
+default: 25
+```
+
+## 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}
+
+## Defined-traffic floors shall meet the directional flatness and levelness limits along the defined wheel paths as scheduled. {note}
+
+## 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}
+
+# Installation {toc}
+
+## The slab shall be placed, struck off, and finished in a continuous operation per section, working from the established screed lines and joints. {note}
+
+## Concrete shall not be placed when ambient or material temperatures fall outside the specified range without approved cold- or hot-weather protection.
+
+```datasheet
+label: Allowable concrete placement temperature
+type: range
+min: 40
+max: 90
+step: 5
+unit: °F
+setpoints: [50, 80]
+default: 70
+```
+
+## Water shall not be added to the surface to aid finishing, as it weakens the wear surface and causes dusting and scaling.
+
+## Finishing operations shall not begin while bleed water is present on the surface. {note}
+
+## 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}
+
+## The surface finish shall be the type required by the floor's service and any subsequent covering.
+
+```datasheet
+label: Surface finish
+type: radio
+options:
+ - Steel-troweled (hard, dense)
+ - Float finish
+ - Broom finish (exterior / slip resistance)
+default: Steel-troweled (hard, dense)
+```
+
+## Exterior slabs, aprons, and dock pads shall be sloped to drain as indicated and shall receive a broom finish for slip resistance. {note}
+
+## Exterior slab drainage slopes and high/low points are indicated [[drawing: exterior slab drainage]]. {note}
+
+# Field Quality Control {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}
+
+## The testing agency shall record slump, air content, temperature, and unit weight for each sampled load.
+
+## 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.
+
+## The finished slab shall be inspected for cracking, and any crack exceeding the specified width shall be evaluated and repaired as directed. {note}
+
+```datasheet
+label: Maximum acceptable crack width before evaluation
+type: range
+min: 0.01
+max: 0.04
+step: 0.005
+unit: in
+default: 0.02
+```
+
+# Delivery, Storage, and Handling {toc}
+
+## Reinforcement and welded wire reinforcement shall be stored off the ground and protected from contaminants that impair bond.
+
+## Vapor retarder material shall be stored protected from sunlight and physical damage until installation.
+
+## 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}
+
+# Warranty {toc}
+
+## The Contractor shall warrant the slab-on-grade against defective materials and workmanship for the specified period from substantial completion.
+
+```datasheet
+label: Workmanship warranty period
+type: range
+min: 1
+max: 5
+step: 1
+unit: years
+default: 1
+```
+
+## Cracking, spalling, scaling, or dusting attributable to defective materials or workmanship within the warranty period shall be repaired at no cost to the Owner. {note}
+
+# Spare Parts {toc}
+
+## The Contractor shall deliver to the Owner the specified quantity of joint filler and sealant matching that installed, for future joint maintenance. {note}
+
+```datasheet
+label: Spare joint filler / sealant
+type: range
+min: 0
+max: 10
+step: 1
+unit: gal
+default: 2
+```