Contents ix
3.7 Problems with formworks 60
3.7.1 Insufficient strength of formworks 60
3.7.2 Too flexible formworks 60
3.7.3 Leaking formworks 60
3.7.4 Wrong positioning of formworks 61
3.7.5 Demoulding problems 62
3.8 Damage in plastic stage 63
3.8.1 Plastic shrinkage 63
3.8.2 Plastic settlement and bleeding 66
References 67
4 Actions during hardening
69
4.1 Introduction 69
4.2 Autogenous shrinkage 70
4.2.1 Mechanism 70
4.2.2 Influencing parameters 73
4.2.2.1 Mineral composition of cement 73
4.2.2.2 Mineral additions and
chemical admixtures 73
4.2.2.3 Water/cement ratio 73
4.2.2.4 Paste volume 74
4.2.3 Mitigation 74
4.2.4 Example 74
4.3 Drying shrinkage 76
4.3.1 Mechanism 76
4.3.2 Influencing parameters 78
4.3.2.1 Parameters related to the
concrete composition 78
4.3.2.2 Geometrical parameters 79
4.3.2.3 Atmospheric parameters 79
4.3.2.4 Technological parameters
during execution 79
4.3.3 Mitigation 80
4.3.4 Example 80
4.4 Thermal shrinkage 82
4.4.1 Mechanism 82
4.4.1.1 Early-age thermal cracking
due to internal restraint 83
4.4.1.2 Early-age thermal cracking
due to external restraint 85