1. Civil Engineering Materials
Department of Civil, Structural and Environmental Engineering
Trinity College Dublin
Roger P. West (TCD)
Peter Flynn (Arup)

2. Section A: Concrete A1 Basic Materials: A2 Fresh Concrete Properties:
A3 Hardened Concrete Properties:
A4 Concrete Mix Design:
A5 Reinforced Concrete:
A6 Pre-stressed Concrete:

3. Section A.3 Hardened Concrete Properties
1. Curing
2. Strength Development
3. Durability
4. Cube/Cylinder Manufacture & Testing
5. Cube Failures
6. Young’s Modulus & Poisson’s Ratio

4. Section A.3 Hardened Concrete Properties
7. Drying Shrinkage
8. Creep
9. Thermal Expansion

5. Section A.3 Hardened Concrete Properties
1. Curing

6. Section A.3 Hardened Concrete Properties: Curing:
Moisture:
Water/Cement Ratio
Free Water
Loss of Water
Retention of Water
Temperature
Standard Temperature – 20oC
Ambient Temperature – 5oC to 30oC
Loss of heat
Heat Differential
Temperature of Concrete
Time
Early Age
Stripping of Formwork
Continuation of Work

7. Section A.3 Hardened Concrete Properties
1. Curing

8. Section A.3 Hardened Concrete Properties
2. Strength Development
Characteristic Compressive Strength:
Test cube or cylinder samples in compression
Strength below which not more than 5% of test results fall. Generally referred to as 28 day strength
Flexural & Indirect Tensile Strength:
Generally taken to be around 10% of its uni-axial compressive strength

9. Section A.3 Hardened Concrete Properties
2. Strength Development

10. Section A.3 Hardened Concrete Properties
2. Strength Development

11. Section A.3 Hardened Concrete Properties
2. Strength Development
Grade
Characteristic Strength (28day)
7day Strength
2month
3month
6month
12month
C20
20.0
13.5
22.0
23.0
24.0
25.0
C25
16.5
27.5
29.0
30.0
31.0
C30
33.0
35.0
36.0
37.0
C40
40.0
28.0
44.0
45.5
47.5
50.0
C50
54.0
55.5
57.5 60

12. Section A.3 Hardened Concrete Properties
2. Strength Development

13. Section A.3 Hardened Concrete Properties
2. Strength Development
Constituents:
Water
Cement
Aggregates
Admixtures

14. Section A.3 Hardened Concrete Properties
2. Strength Development
Methods of Preparation:
Batching
Mixing
Placing
Compaction

15. Section A.3 Hardened Concrete Properties
2. Strength Development
Test Conditions for compressive strength testing:
Specimen Shape & Size
Specimen Moisture Content
Specimen Temperature
Bearing Surface Conditions
Method of Loading

16. Section A.3 Hardened Concrete Properties
3. Durability
Durability of concrete is its resistance to
weathering, chemical attack, abrasion,
frost and fire.
Permeability should be as low as possible and is improved by;
Full compaction
Proper curing
Low water content
High cement content

17. Section A.3 Hardened Concrete Properties
3. Durability
Carbonation
Reinforcement is protected by highly alkaline pore water in the hardened concrete
Carbon dioxide in the air neutralises the free lime.
If the reaction reaches the reinforcement corrosion will occur.
Very slow process dependent on permeability

18. Section A.3 Hardened Concrete Properties
3. Durability
Chloride Attack
Slow process dependent on permeability
Attacks steel quickly if chloride ions can permeate concrete cover
Sources are sea water and de-icing salts predominantly
Keep surface permeability as high as possible through compaction, curing and using alternative cement materials

19. Section A.3 Hardened Concrete Properties
3. Durability
Frost Resistance
Depends on permeability
Improved by the use of air-entraining agent
Chemical Attack
OPC is subject to attack by acids including organic acids and acid fumes
Also attacked by sulphates in the ground and ground water
Resisted by;
Appropriate cement
Correct concrete mix design
Dense & well compacted

20. Section A.3 Hardened Concrete Properties
3. Durability
Alkali-silica Reaction
A reactive form of silica is present in the aggregate
Pore solution contains sodium, potassium & hydroxyl ions and has a high alkalinity (released during hydration)
Water is available

21. Section A.3 Hardened Concrete Properties
3. Durability
Fire Resistance
Concrete is non-flammable
Low thermal conductivity

22. Section A.3 Hardened Concrete Properties
4. Cube/Cylinder Manufacture & Testing

23. Section A.3 Hardened Concrete Properties
4. Cube/Cylinder Manufacture & Testing

24. Section A.3 Hardened Concrete Properties
Cube
Failures

25. Section A.3 Hardened Concrete Properties
Cube
Failures

26. Section A.3 Hardened Concrete Properties
6. Young’s Modulus & Poisson’s Ratio
E is influenced by;
Elastic properties of the aggregates
Conditions of curing
Age of concrete
Mix proportions
Type of cement
For concrete Young’s modulus is taken as approx 28kN/mm2 (GPa)

27. Section A.3 Hardened Concrete Properties
6. Young’s Modulus & Poisson’s Ratio

28. Section A.3 Hardened Concrete Properties
6. Young’s Modulus & Poisson’s Ratio

29. Section A.3 Hardened Concrete Properties
6. Young’s Modulus & Poisson’s Ratio

30. Section A.3 Hardened Concrete Properties
6. Young’s Modulus & Poisson’s Ratio
n = - etrans / elongitudinal
For Concrete Poisson’s Ratio is taken as The phenomenon explains why cubes fail in compression.

31. Section A.3 Hardened Concrete Properties
7. Drying Shrinkage
Dependent on;
Humidity
Temperature of surrounding air
Rate of air flow over surface
Ratio of surface area to the volume of concrete
Water & cement contents
Curing

32. Section A.3 Hardened Concrete Properties
7. Drying Shrinkage
50% of all shrinkage between 1month to 1 year depending on mass
May be controlled by reinforcement details

33. Section A.3 Hardened Concrete Properties
7. Drying Shrinkage

34. Section A.3 Hardened Concrete Properties
8. Creep
Dependent on;
Humidity
Temperature of surrounding air
Cement Content
Water/cement ratio
Type of cement & aggregate

35. Section A.3 Hardened Concrete Properties
8. Creep

36. Section A.3 Hardened Concrete Properties
8. Creep
Takes place over many months
Elastic Recovery
Restrained by Reinforcement

37. Section A.3 Hardened Concrete Properties
8. Creep

38. Section A.3 Hardened Concrete Properties
9. Thermal Expansion
Influenced by;
Types of Aggregates
Water content
Mix Proportions
Varies from 0.5 to 1.2 x 10-5 / oC