ACI 231R 10:2010 Edition

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231R-10 Report on Early-Age Cracking: Causes, Measurement and Mitigation

Published By	Publication Date	Number of Pages
ACI	2010	50

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Description

Early-age cracking is a challenge for the concrete industry. Materials selection, environmental conditions, and field practices all have considerable influence on the propensity for early-age cracking to occur. This document focuses on thermal- and moisture-related deformations; both are materials-related and contribute to early-age cracking. The document provides detailed reviews on the causes of deformation and cracking, test methods for assessing shrinkage and thermal deformation properties, and mitigation strategies for reducing early-age cracking. Keywords: autogenous shrinkage; cracking; early-age; heat of hydration; measurement; mitigation methods; microstructure; shrinkage; shrinkage cracking; sustainability; thermal cracking; thermal properties.

PDF Catalog

PDF Pages	PDF Title
3	CONTENTS
4	CHAPTER 1— INTRODUCTION AND SCOPE 1.1— Introduction 1.2—Scope CHAPTER 2— NOTATION AND DEFINITIONS 2.1— Notation
5	2.2—Definitions CHAPTER 3— CAUSES OF EARLY-AGE DEFORMATION AND CRACKING 3.1—Thermal deformation
7	3.1.1 Influence of placement temperature 3.1.2 Influence of concrete mixture compositions 3.1.2.1 Aggregates
8	3.1.3 Cement types and sources 3.1.3.1 Cement content and fly ash
9	3.1.3.2 Slag cement 3.1.3.3 Air-entraining admixtures 3.2—Autogenous shrinkage 3.2.1 Influence of water-cementitious material ratio
10	3.2.2 Influence of aggregate 3.2.3 Influence of supplementary cementitious materials
11	3.3—Drying shrinkage 3.4—Creep and stress relaxation from deformation restraint
12	3.5—Mitigation of shrinkage CHAPTER 4— TEST METHODS AND ASSESSMENT 4.1—Introduction 4.2—Shrinkage measurements 4.2.1 Drying shrinkage
13	4.2.2 Autogenous shrinkage
14	4.3—Ring test 4.3.1 Quantitative restrained ring tests 4.3.2 Stress development
16	4.3.3 Quantifying effect of stress relaxation (creep) using ring
17	4.3.4 Influence of moisture gradients
18	4.3.5 Influence of degree of restraint R 4.3.6 Influence of specimen geometry and bond between the concrete and steel 4.3.7 Effect of variable concrete wall thickness (eccentricity) 4.3.8 Cracking potential classification
19	4.3.9 Cracking potential envelopes 4.3.10 Developments for advancement of restrained ring analysis 4.3.10.1 Measurement variability 4.3.10.2 Dual ring
20	4.3.11 Summary of developments on ring test 4.4—Rigid cracking frames 4.4.1 Test setup
22	4.4.2 Thermal stresses 4.4.3 Shrinkage deformation and stresses
23	4.4.4 Creep and stress relaxation
25	4.4.5 Degree of restraint 4.4.6 Summary of cracking frame test
26	4.5—Coefficient of thermal expansion ( measurement
27	4.6—Analysis tools assessing stresses and cracking 4.6.1 4C–Temp&Stress software
28	4.6.2 High Performance Concrete Paving (HIPERPAV) software 4.6.3 MLS software
29	CHAPTER 5— SHRINKAGE CONTROL 5.1— Introduction 5.2—Expansive additives
30	5.3—Shrinkage-reducing admixtures 5.3.1 How SRAs work
31	5.3.2 Brief history of development of SRAs 5.3.3 Shrinkage-reducing chemical admixture materials 5.3.4 Application of SRAs 5.3.5 Shrinkage-reducing chemical admixtures and their impact on shrinkage and cracking
32	5.3.5.1 Influence of SRAs on autogenous shrinkage 5.3.5.2 Influence of SRA on plastic shrinkage
34	5.3.5.3 Influence of SRA on drying shrinkage 5.3.5.4 Overall shrinkage measurements for concrete containing SRA
35	5.3.6 Influence of SRA on shrinkage cracking
36	5.3.7 Influence of SRA on mechanical properties and durability 5.3.7.1 Mechanical properties of concrete containing SRA
37	5.3.7.2 Durability properties of concrete containing SRA
38	5.4—Internal curing 5.4.1 General 5.4.2 Lightweight aggregates 5.4.3 Superabsorbent polymers
39	5.4.4 Mixture proportioning for internal curing 5.4.5 Water movement during internal curing (X-ray microtomography) 5.4.6 Effect of internal curing on early-age shrinkage
40	5.4.7 Effect of internal curing on early-age strength
41	CHAPTER 6— REFERENCES 6.1— Referenced standards and reports
42	6.2—Cited references