A Guide to the Common Properties of Concrete

1.0 Introduction 1
2.0 Types of Specification 1
2.1 Prescriptive specifications 1
2.2 Performance-based specifications 1
2.3 Common forms of specification 1
2.4 Comment 1
3.0 Existing specifications 1
3.1 Standard Specifications 1
3.2 Particular or project specifications 2
4.0 Specification of concrete and concrete structures 2
5.0 Materials for concrete 2
5.1 Cement 2
5.1.1 Cement type and extenders 3
5.1.2 Choice of cement type 3
5.2 Aggregates for concrete 4
5.2.1 Effect of the properties of fine aggregate grading on concrete 4
5.2.1.2 Workability of the concrete mix 4
5.2.1.3 Smoothness of concrete finishes 5
5.2.1.4 Water requirement of concrete 5
5.2.1.5 Durability of concrete 5
5.2.1.6 Bleeding of concrete 5
5.2.2 Effect of the properties of coarse aggregate on concret 5
5.2.2.1 Grading 5
5.2.2.2 Size 5
5.2.2.3 Shape 6
5.2.2.4 Strength 6
5.2.2.5 Shrinkage 6
5.2.2.6 Alkali aggregate reaction 6
5.3 Admixtures 7
5.3.1 Types of admixture 7
5.3.1.1. Retarding admixtures 7
5.3.1.2 Accelerating admixtures 7
5.3.1.3 Plasticising admixtures 7
5.3.1.4 Superplasticising admixtures 7
5.3.1.5 Air-entraining admixtures 7
6.0 Fresh concrete 8
6.1 Lubrication of the concrete mix 8
6.1.1 Lubrication by water 8
6.1.2 Lubrication by sand 8
6.1.3 Lubrication by admixture 8
6.1.4 Lubrication by vibration 8
6.1.5 Temperature of fresh concrete 8
6.2 Workability and its assessment 9
6.2.1 Workability of fresh concrete during transport 9
6.3 Bleeding of concrete 9
6.3.1 Measurement and control of bleeding 10
6.4 Cohesion 10
6.4.1 Achieving a cohesive mix 10
6.5 Compaction 11
6.5.1 Assessment of compaction 11
6.6 Plastic cracking of concrete 12
6.6.1 Plastic-settlement cracks 12
6.6.1.1 Effect and reduction of plastic-settlement cracks 12
6.6.2 Plastic shrinkage cracks 12
6.6.2.1 Reduction of plastic-shrinkage cracking 13
6.7 Construction joints 14
6.7.1 Location of construction joints 14
6.7.2 Surface preparation of construction joints 14
7.0 Green concrete 15
7.1 Finishing 15
7.2 Curing 15
7.3 Thermal cracking of concrete 15
8.0 Hardened concrete 16
8.1 Compressive strength 16
8.1.1 Measurement of compressive strength by the cube test 16
8.1.1.1 Making and curing of concrete cubes 16
8.1.1.2 Testing of concrete cubes 16
8.1.1.3 Assessment of cube test results 16
8.1.2 Measurement of compressive strength by drilling and crushing cores 17
8.1.2.1 Drilling of concrete cores 17
8.1.2.2 Testing of cores 17
8.1.2.3 Assessment of core test results 18
8.1.3 Measurement of compressive strength by non-destructive tests 18
8.1.3.1 Rebound or Schmidt hammer 18
8.1.3.2 Ultrasonic testing 18
8.1.3.3 Pull out tests 18
8.1.3.4 Load test 19
8.2 Flexxural strength 19
8.2.1 Estimation of flexural strength 19
8.3 Strength strength 19
8.4 Shrinkage of hardened concrete 19
8.5 Abrasion resistance 20
8.5.1 Achievement of abrasion resistance 20
8.5.2 Measurement of abrasion resistance 20
8.6 Durability and cover thicknes over steel rebar 20
8.6.1 Acievement and specification of concrete for durability 21
8.7 Modulus of elasticity 22
8.7.1 Influence of the modulus of elasticity 22
9.0 Finishes 23
9.1 Achievement of high quality finishes 23
9.2 Subsequent finishes 23
9.3 Strength of bond 23
9.4 Allignment of finishes and building tolerances 23
10.0 Specialised structures 23
10.1 Concrete industrial floors 23
10.1.1 Surface flatness tolerance 23
10.1.2 Jointing of floors 24
10.1.3 Shrinkage of concrete in floors 24
10.1.4 Use of reinforcement 25
10.1.5 Use of plastic sheet under floor slabs 25
10.1.6 Power floating of a concrete surface 25
10.2 Sand-cement mixes 26
10.2.1 Mortars 26
10.2.2 Plasters 26
10.2.3 Screeds 26
Appendix A 28
Appendix A2 30
Properties of Structure 34
Properties of Sand-Cement Mixes 35
Appendix B 37
Appendix C 40
Appendix D 42