Abstract: 

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Environmental factors, such as high ambient temperature, low humidity, high wind, or both low humidity and high wind, affect concrete properties and the construction operations of mixing, transporting, and placing of the concrete materials. This guide provides measures that can be taken to minimize the undesirable effects of these environmental factors and reduce the potential for serious problems.

This guide defines hot weather, discusses potential problems, and presents practices intended to minimize them. These practices include selecting materials and proportions, precooling ingredients, and batching. Other topics discussed include length of haul, consideration of concrete temperature as placed, facilities for handling concrete at the site, and, during the early curing period, placing and curing techniques, and appropriate testing and inspection procedures in hot weather conditions. The materials, processes, quality control measures, and inspections described in this document should be tested, monitored, or performed as applicable only by individuals holding the appropriate ACI certifications or equivalent.

Keywords: air entrainment; cooling; curing; evaporation; high temperature; hot weather construction; plastic shrinkage; production methods; retempering; slump tests; water content.

Contents: Chapter 1—Introduction and scope, p. 2

1.1—Introduction

1.2—Scope

Chapter 2—Notation and definitions, p. 2

2.1—Notation

2.2—Definitions

Chapter 3—Potential problems and practices, p. 3

3.1—Potential problems in hot weather

3.2—Potential problems related to other factors

3.3—Practices for hot weather concreting

Chapter 4—Effects of hot weather on concrete properties, p. 3

4.1—General

4.2—Estimating evaporation rate

4.3—Temperature of concrete

4.4—Ambient conditions

4.5—Water

4.6—Cement

4.7—Supplementary cementitious materials

4.8—Chemical admixtures

4.9—Aggregates

4.10—Proportioning

Chapter 5—Production and delivery, p. 14

5.1—General

5.2—Temperature control of concrete

5.3—Batching and mixing

5.4—Delivery

5.5—Slump adjustment

5.6—Properties of concrete mixtures

5.7—Retempering

Chapter 6—Placing and curing, p. 16

6.1—General

6.2—Preparations for placing and curing

6.3—Placement and finishing

6.4—Curing and protection

Chapter 7—Testing and inspection, p. 19

7.1—Testing

7.2—Inspection

Chapter 8—References, p. 20

8.1—Referenced standards and reports

8.2—Cited references

Appendix A—Estimating concrete temperature,pp. 22

A.1—Estimating temperature of freshly mixed concrete

A.2—Estimating temperature of concrete with ice

Appendix B—Methods for cooling fresh concrete,p. 23

B.1—Cooling with chilled mixing water

B.2—Liquid nitrogen cooling of mixing water

B.3—Cooling concrete with ice

B.4—Cooling mixed concrete with liquid nitrogen

B.5—Cooling of coarse aggregates