Abstract: 

Preview

The objectives of cold weather concreting practices are to prevent damage to concrete due to freezing at early ages, ensure that the concrete develops the required strength for safe removal of forms, maintain curing conditions that foster normal strength development, limit rapid temperature changes, and provide protection consistent with the intended serviceability of the structure.

Concrete placed during cold weather will develop sufficient strength and durability to satisfy intended service requirements when it is properly produced, placed, and protected. This guide provides information for the contractor to select the best methods to satisfy the minimum cold weather concreting requirements.

This guide discusses: concrete temperature during mixing and placing, temperature loss during delivery, preparation for cold weather concreting, protection requirements for concrete that does not require construction supports, estimating strength development, methods of protection, curing requirements, and admixtures for accelerating setting and strength gain including antifreeze admixtures. 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: accelerating admixtures; antifreeze admixtures; cold weather concreting; concrete temperature; curing; enclosures; form removal; freezing and thawing; heaters; heating aggregates; insulating materials; maturity testing; protection; strength development.

Contents: Chapter 1—Introduction, p. 2

Chapter 2—Notation and definitions, p. 2

2.1—Notation

2.2—Definitions

Chapter 3—Objectives, principles, and economy,p. 3

3.1—Objectives

3.2—Principles

3.3—Economy

Chapter 4—General requirements, p. 4

4.1—Planning

4.2—Protection during unexpected freezing

4.3—Concrete temperature

4.4—Temperature records

4.5—Heated enclosures

4.6—Finishing air-entrained slabs

4.7—Concrete workability

Chapter 5—Temperature of concrete as mixed and placed, and heating of materials, p. 5

5.1—Placement temperature

5.2—Mixing temperature

5.3—Heating mixing water

5.4—Heating aggregates

5.5—Steam heating of aggregates

5.6—Overheating of aggregates

5.7—Calculation of mixture temperature

5.8—Temperature loss during delivery

Chapter 6—Preparation before concreting, p. 7

6.1—Preparation of surfaces in contact with fresh concrete

6.2—Massive metallic embedments

6.3—Subgrade condition

Chapter 7—Protection against freezing and protection for concrete not requiring construction supports, p. 8

7.1—Protection methods

7.2—Protection period

7.3—Protection for strength gain

7.4—Temperature drop after removal of protection

7.5—Allowable temperature differential during stripping

Chapter 8—Protection for structural concrete requiring construction supports, p. 9

8.1—Introduction

8.2—Field-cured cylinders

8.3—In-place testing

8.4—Maturity testing

8.5—Attainment of design strength

8.6—Increasing early strength

8.7—Cooling of concrete

8.8—Estimating strength development

8.9—Removal of forms and supports

8.10—Specification recommendations

8.11—Estimating strength development—modeling of cold weather placements

Chapter 9—Equipment, materials, and methods of temperature protection, p. 14

9.1—Introduction

9.2—Insulating materials

9.3—Selection of insulation when supplementary heat is not used

9.4—Selection of insulation for use with hydronic heaters

9.5—Heaters

9.6—Enclosures

9.7—Internal heating

9.8—Temperature monitoring

9.9—Temporary removal of protection

9.10—Insulated forms

Chapter 10—Curing requirements and methods, p. 21

10.1—Introduction

10.2—Curing during the protection period

10.3—Curing following the protection period

Chapter 11—Acceleration of setting and strength development, p. 21

11.1—Introduction

11.2—Accelerating admixtures

11.3—Rapid-setting cements

Chapter 12—References, p. 24

12.1—Referenced standards and reports

12.2—Cited references