Corpus sync: neutrality remakes, note hygiene, datasheet relocation, transformer-split cross-refs
---
title: Slab-on-Grade
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## Slab classification {toc}
−### The slab classification shall be selected to match the structural demand and crack-control strategy of the application. {note}
+### The slab classification shall be selected to match the structural demand and crack-control strategy of the application.
−### 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
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```
+### 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}
+
### Plain slabs rely entirely on closely spaced contraction joints to control random cracking and are appropriate only for lightly and uniformly loaded floors. {note}
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```
−## The subgrade modulus of subgrade reaction (k-value) used in design shall be established by geotechnical evaluation of the prepared subgrade. {note}
+## The subgrade modulus of subgrade reaction (k-value) used in design shall be established by geotechnical evaluation of the prepared subgrade.
−## 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)
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```
−## 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}
+## 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}
+## Where the slab will receive moisture-sensitive flooring, the design shall account for under-slab moisture control through the vapor retarder and curing method.
+
# Subgrade and Subbase {toc}
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step: 1
unit: '% of optimum'
−setpoints: [-2, 0, 2]
+setpoints: [-3, -2, 0, 2, 3]
default: 0
```
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```
−## The subbase shall be compacted and trimmed to the specified elevation tolerance to control slab thickness. {note}
+## The subbase shall be compacted and trimmed to the specified elevation tolerance to control slab thickness.
## 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}
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step: 0.25
unit: in
−setpoints: [0.5, 0.75]
+setpoints: [0.5, 0.75, 1]
default: 0.75
```
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step: 0.01
unit: w/cm
−setpoints: [0.45, 0.50]
+setpoints: [0.4, 0.45, 0.5, 0.55]
default: 0.50
```
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step: 0.5
unit: in
−setpoints: [4, 5]
+setpoints: [3, 4, 5, 6]
default: 5
```
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## 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}
+## 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)
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## 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}
+## 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.
# Slab Thickness {toc}
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step: 0.5
unit: in
−setpoints: [5, 6, 8]
+setpoints: [4, 5, 6, 8, 12]
default: 6
```
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step: 0.125
unit: in
−setpoints: [-0.375, 0.375]
+setpoints: [-0.375, 0.375, 0.5]
default: -0.375
```
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```
−### 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}
+### Contraction joint panels shall be kept as close to square as practical, with the long-to-short side ratio not exceeding the specified maximum.
−### 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
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```
+### 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}
+
### 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.
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```
−### Saw-cutting shall begin as soon as the concrete will support the saw without raveling and before shrinkage cracking develops. {note}
+### Saw-cutting shall begin as soon as the concrete will support the saw without raveling and before shrinkage cracking develops.
### 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}
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step: 1
unit: hours
−setpoints: [4, 8]
+setpoints: [2, 4, 8, 12]
default: 4
```
## 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}
+### Isolation joints shall be provided at all columns, walls, footings, equipment pads, and fixed penetrations to separate the slab from restraint.
### 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}
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```
−### Column isolation joints shall be diamond-shaped (turned 45°) or circular so the slab can shrink away from the column on all sides. {note}
+### Column isolation joints shall be diamond-shaped (turned 45°) or circular so the slab can shrink away from the column on all sides.
## 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}
+### 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.
### 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}
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step: 1
unit: days
−setpoints: [3, 7]
+setpoints: [3, 7, 14]
default: 7
```
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## 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}
+## In hot, dry, or windy conditions, an evaporation retarder shall be applied to the bleeding surface to prevent plastic shrinkage cracking before final finishing.
## 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}
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step: 5
unit: FF
−setpoints: [25, 35]
+setpoints: [20, 25, 35, 50]
default: 35
```
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step: 5
unit: FL
−setpoints: [20, 25]
+setpoints: [15, 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}
+## Defined-traffic floors shall meet the directional flatness and levelness limits along the defined wheel paths as scheduled.
## 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}
+## The slab shall be placed, struck off, and finished in a continuous operation per section, working from the established screed lines and joints.
## Concrete shall not be placed when ambient or material temperatures fall outside the specified range without approved cold- or hot-weather protection.
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step: 5
unit: °F
−setpoints: [50, 80]
+setpoints: [40, 50, 80, 90]
default: 80
```
## 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}
+## Finishing operations shall not begin while bleed water is present on the surface.
## 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}
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## 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}
+## The finished slab shall be inspected for cracking, and any crack exceeding the specified width shall be evaluated and repaired as directed.
```datasheet
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```
−## 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}
+## Cracking, spalling, scaling, or dusting attributable to defective materials or workmanship within the warranty period shall be repaired at no cost to the Owner.
# 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}
+## The Contractor shall deliver to the Owner the specified quantity of joint filler and sealant matching that installed, for future joint maintenance.
```datasheet
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default: 2
```