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Chemical admixtures, which are primarily water-soluble substances, are discussed in detail and, in this report, are classified into 13 groups: airentraining; accelerating; water-reducing and set-retarding; admixtures for flowing concrete; admixtures for self-consolidating concrete; cold weather admixture systems; admixtures for very high-early-strength concrete; extended set control; shrinkage-reducing; corrosion-inhibiting; lithium; permeability-reducing; and miscellaneous. Chemical admixtures are used on a daily basis in the cast-in-place and precast concrete industries. Twelve categories of admixtures are described in detail as to type, current usage, and their effect on concrete in the plastic and hardened state. Their benefits and common usage are outlined.

Each category of admixture addresses the benefits obtainable with their use in a properly proportioned concrete mixture, types of batching systems, control measures, and test placements for mixture design verification. Mixture designs using multiple chemical admixtures have become more common. Their successful usage requires proper compatibility and, often, setting times and early strengths that are proper for the placing environment. The potential benefits are highlighted to all members of the concrete team, concrete contractor, concrete producer, admixture supplier, and testing personnel.

Finely divided mineral admixtures are addressed by ACI 232.2R “Use of Fly Ash in Concrete,” ACI 232.1R “Use of Raw or Processed Natural Pozzolans in Concrete” and ACI 234R “Guide for the Use of Silica Fume in Concrete.”

Keywords: accelerating; admixture; admixture system; air-entraining; alkali-aggregate reaction; flowing concrete; high-range water-reducing admixture; permeability-reducing admixtures; self-consolidating concrete; shrinkage-reducing; water-reducing and set-retarding.

Contents: Chapter 1—Introduction, p. 4

1.1—Introduction

Chapter 2—Definitions, p. 4

2.1—Definitions

Chapter 3—General information, p. 5

3.1—Sustainability

3.2—Admixture benefits

3.3—Specifications for admixtures

3.4—Sampling and testing

3.5—Cost effectiveness

3.6—Selection and evaluation

3.7—Proportioning and batching

Chapter 4—Air-entraining admixtures, p. 8

4.1—Introduction

4.2—Materials for air entrainment

4.3—Selection and evaluation

4.4—Applications

4.5—Proportioning concrete

4.6—Effects on fresh and hardening concrete

4.7—Effects on hardened concrete

4.8—Quality assurance

4.9—Batching

4.10—Storage

Chapter 5—Accelerating admixtures, p. 12

5.1—Introduction

5.2—Materials

5.3—Selection and evaluation

5.4—Applications

5.5—Proportioning concrete

5.6—Effects on fresh and hardening concrete

5.7—Effects on hardened concrete

5.8—Corrosion of metals

5.9—Quality assurance

5.10—Batching

5.11—Storage

Chapter 6—Water-reducing and set-retarding admixtures, p. 16

6.1—Introduction

6.2—Materials

6.3—Selection and evaluation

6.4—Applications

6.5—Dosage

6.6—Proportioning concrete

6.7—Effects on fresh and hardening concrete

6.8—Effects on hardened concrete

6.9—Batching and quality control

6.10—Storage

Chapter 7—Admixtures for flowing concrete, p. 20

7.1—Introduction

7.2—Materials

7.3—Selection and evaluation

7.4—Applications

7.5—Proportioning concrete

7.6—Effects on fresh and hardening concrete

7.7—Effects on hardened concrete

7.8—Quality assurance

7.9—Storage

Chapter 8—Admixtures for self-consolidating concrete, p. 23

8.1—Introduction

8.2—Materials for SCC admixtures

8.3—Selection and evaluation

8.4—Proportioning concrete

8.5—Effects on fresh and hardening concrete

8.6—Effects on hardened concrete

8.7—Quality assurance

8.8—Batching

8.9—Storage

Chapter 9—Cold weather admixture systems, p. 28

9.1—Introduction

9.2—Materials

9.3—Selection and evaluation

9.4—Proportioning concrete

9.5—Batching

9.6—Trial placement

9.7—Placing and finishing

9.8—Effects on fresh and hardening concrete

9.9—Effects on hardened concrete

9.10—Quality assurance

9.11—Cost benefit

9.12—Storage

Chapter 10—Admixtures for very high-earlystrength concrete, p. 30

10.1—Introduction

10.2—Materials for very high-early-strength concrete

10.3—Selection and evaluation

10.4—Proportioning concrete

10.5—Effects on fresh and hardening concrete

10.6—Effects on hardened concrete

10.7—Quality assurance

10.8—Batching

10.9—Storage

Chapter 11—Extended set-control admixtures,p. 33

11.1—Introduction

11.2—Materials

11.3—Selection and evaluation

11.4—Applications

11.5—Proportioning concrete

11.6—Effects on fresh and hardening concrete

11.7—Effects on hardened concrete

11.8—Quality assurance

11.9—Batching

11.10— Storage

Chapter 12—Shrinkage-reducing admixtures, p. 35

12.1—Introduction

12.2—Materials

12.3—Mode of action

12.4—Applications

12.5—Proportioning concrete

12.6—Effects on fresh and hardening concrete

12.7—Effects on hardened concrete

12.8—Quality assurance

12.9—Storage

Chapter 13—Corrosion-inhibiting admixtures, p. 37

13.1—Introduction

13.2—Materials

13.3—Selection and evaluation

13.4—Applications

13.5—Proportioning concrete

13.6—Effects on fresh and hardening concrete

13.7—Effects on hardened concrete

13.8—Quality assurance

13.9—Storage

Chapter 14—Lithium admixtures to reduce deleterious expansion from alkali-silica reaction,p. 44

14.1—Introduction

14.2—Materials

14.3—Mechanism

14.4—Dosage

14.5—Effects on concrete properties

14.6—Performance tests for effectiveness

14.7—Storage

Chapter 15—Permeability-reducing admixtures,p. 46

15.1—Introduction

15.2—Materials

15.3—Selection and evaluation

15.4—Applications

15.5—Proportioning concrete

15.6—Effects on fresh and hardened concrete

15.7—Quality assurance

15.8—Batching

15.9—Storage

Chapter 16—Miscellaneous admixtures, p. 50

16.1—Bonding admixtures

16.2—Coloring admixtures

16.3—Flocculating admixtures

16.4—Fungicidal, germicidal, and insecticidal admixtures

16.5—Rheology- and viscosity-modifying admixtures

16.6—Air-detraining admixtures

16.7—Storage

Chapter 17—References, p. 52

17.1—Referenced standards and reports

17.2—Cited references