302.1R-04: Guide for Concrete Floor and Slab Construction

302.1R-04: Guide for Concrete Floor and Slab Construction

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The quality of a concrete floor or slab is highly dependent on achieving a hard and durable surface that is flat, relatively free of cracks, and at the proper grade and elevation. Properties of the surface are determined by the mixture proportions and the quality of the concreting and jointing operations. The timing of concreting operations--especially finishing, jointing, and curing--is critical. Failure to address this issue can contribute to undesirable characteristics in the wearing surface such as cracking, low resistance to wear, dusting, scaling, high or low spots, poor drainage, and increasing the potential for curling.

Concrete floor slabs employing portland cement, regardless of slump, will start to experience a reduction in volume as soon as they are placed. This phenomenon will continue as long as any water, heat, or both, is being released to the surroundings. Moreover, because the drying and cooling rates at the top and bottom of the slab will never be the same, the shrinkage will vary throughout the depth, causing the as-cast shape to be distorted and reduced in volume.

This guide contains recommendations for controlling random cracking and edge curling caused by the concrete’s normal volume change. Application of present technology permits only a reduction in cracking and curling, not elimination. Even with the best floor designs and proper construction, it is unrealistic to expect crack-free and curl-free floors. Consequently, every owner should be advised by both the designer and contractor that it is normal to expect some amount of cracking and curling on every project, and that such occurrence does not necessarily reflect adversely on either the adequacy of the floor’s design or the quality of its construction (Ytterberg 1987; Campbell et al. 1976).

Refer to the latest edition of ACI 360R for a detailed discussion of shrinkage and curling in slabs-on-ground. Refer to the latest edition of ACI 224R for a detailed discussion of cracking in reinforced and nonreinforced concrete slabs.

This guide describes how to produce high-quality concrete slabs-onground and suspended floors for various classes of service. It emphasizes aspects of construction such as site preparation, concreting materials, concrete mixture proportions, concreting workmanship, joint construction, load transfer across joints, form stripping procedures, finishing methods, and curing. Flatness/levelness requirements and measurements are outlined. A thorough preconstruction meeting is critical to facilitate communication among key participants and to clearly establish expectations and procedures that will be employed during construction to achieve the floor qualities required by the project specifications. Adequate supervision and inspection are required for job operations, particularly those of finishing.

Keywords: admixture; aggregate; concrete; consolidation; contract docu-ments;

curing; curling; deflection; durability; form; fracture; joint; mixture

proportioning; mortar, paste, placing; quality control; slab-on-ground;

slabs; slump test; specification.


Document Details

Author: ACI Committee 302

Publication Year: 2004

Pages: 76

ISBN: 9780870311512

Categories: Slabs

Formats: Protected PDF/Web View

This document is Historical

Table of Contents

Chapter 1—Introduction

1.1—Purpose and scope


1.3—Related work of other committees

Chapter 2—Classes of floors

2.1—Classification of floors

2.2—Single-course monolithic floors: Classes 1, 2, 4, 5,and 6

2.3—Two-course floors: Classes 3, 7, and 8

2.4—Class 9 floors

2.5—Special finish floors

Chapter 3—Design considerations



3.3—Suspended slabs

3.4—Miscellaneous details

Chapter 4—Site preparation and placing environment

4.1—Soil-support system preparation

4.2—Suspended slabs


4.4—Setting screed guides

4.5—Installation of auxiliary materials

4.6—Concrete placement conditions

Chapter 5—Materials



5.3—Portland cement



5.6—Curing materials


5.8—Liquid surface treatments


5.10—Evaporation reducers

5.11—Gloss-imparting waxes

5.12—Joint materials

5.13—Volatile organic compounds (VOC)

Chapter 6—Concrete properties and consistency

6.1—Concrete properties

6.2—Recommended concrete mixture

6.3—Concrete mixture analysis

Chapter 7—Batching, mixing, and transporting




Chapter 8—Placing, consolidating, and finishing

8.1—Placing operations

8.2—Tools for spreading, consolidating, and finishing

8.3—Spreading, consolidating, and finishing operations

8.4—Finishing Class 1, 2, and 3 floors

8.5—Finishing Class 4 and 5 floors

8.6—Finishing Class 6 floors and monolithic-surface

treatments for wear resistance

8.7—Finishing Class 7 floors

8.8—Finishing Class 8 floors (two-course unbonded)

8.9—Finishing Class 9 floors

8.10—Toppings for precast floors

8.11—Finishing lightweight concrete

8.12—Nonslip floors

8.13—Decorative and nonslip treatments

8.14—Grinding as a repair procedure

8.15—Floor flatness and levelness

8.16—Treatment when bleeding is a problem

8.17—Delays in cold-weather finishing

Chapter 9—Curing, protection, and joint filling

9.1—Purpose of curing

9.2—Methods of curing

9.3—Curing at joints

9.4—Curing special concrete

9.5—Length of curing

9.6—Preventing plastic-shrinkage cracking

9.7—Curing after grinding

9.8—Protection of slab during construction

9.9—Temperature drawdown in cold storage and freezer rooms

9.10—Joint filling and sealing

Chapter 10—Quality control checklist


10.2—Partial list of important items to be observed

Chapter 11—Causes of floor and slab surface imperfections



11.3—Low wear resistance




11.7—Blisters and delamination



11.10—Low spots and poor drainage


11.12—Analysis of surface imperfections

Chapter 12—References

12.1—Referenced standards and reports

12.2—Cited references

12.3—Other references


Any applicable errata are included with individual documents at the time of purchase. Errata are not included for collections or sets of documents such as the Manual of Concrete Practice (MCP). For a listing of and access to all product errata, visit the Errata page.

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