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2E8 Materials (Civil Engineering Component) Civil Engineering Materials Department of Civil, Structural and Environmental Engineering Trinity College Dublin.

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Presentation on theme: "2E8 Materials (Civil Engineering Component) Civil Engineering Materials Department of Civil, Structural and Environmental Engineering Trinity College Dublin."— Presentation transcript:

1 2E8 Materials (Civil Engineering Component) Civil Engineering Materials Department of Civil, Structural and Environmental Engineering Trinity College Dublin Roger P. West (TCD) Peter Flynn (Arup)

2 2E8 Materials (Civil Engineering Component) Section A:Concrete A1Basic Materials: A2Fresh Concrete Properties: A3Hardened Concrete Properties: A4Concrete Mix Design: A5Reinforced Concrete: A6Pre-stressed Concrete:

3 2E8 Materials (Civil Engineering Component) Section A.3Hardened 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 2E8 Materials (Civil Engineering Component) Section A.3Hardened Concrete Properties 7. Drying Shrinkage 8. Creep 9. Thermal Expansion

5 2E8 Materials (Civil Engineering Component) Section A.3 Hardened Concrete Properties 1.Curing

6 2E8 Materials (Civil Engineering Component) Section A.3 Hardened Concrete Properties: Curing: Moisture: Water/Cement Ratio Free Water Loss of Water Retention of Water Temperature Standard Temperature – 20 o C Ambient Temperature – 5 o C to 30 o C Loss of heat Heat Differential Temperature of Concrete Time Early Age Stripping of Formwork Continuation of Work

7 2E8 Materials (Civil Engineering Component) Section A.3 Hardened Concrete Properties 1.Curing

8 2E8 Materials (Civil Engineering Component) 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 2E8 Materials (Civil Engineering Component) Section A.3 Hardened Concrete Properties 2.Strength Development

10 2E8 Materials (Civil Engineering Component) Section A.3 Hardened Concrete Properties 2.Strength Development

11 2E8 Materials (Civil Engineering Component) Section A.3 Hardened Concrete Properties 2.Strength Development Grade Characteristic Strength (28day) 7day Strength 2month3month6month12month C20 20.013.522.023.024.025.0 C25 25.016.527.529.030.031.0 C30 30.020.033.035.036.037.0 C40 40.028.044.045.547.550.0 C50 50.036.054.055.557.560

12 2E8 Materials (Civil Engineering Component) Section A.3 Hardened Concrete Properties 2.Strength Development

13 2E8 Materials (Civil Engineering Component) Section A.3 Hardened Concrete Properties 2.Strength Development Constituents: Water Cement Aggregates Admixtures

14 2E8 Materials (Civil Engineering Component) Section A.3 Hardened Concrete Properties 2.Strength Development Methods of Preparation: Batching Mixing Placing Compaction

15 2E8 Materials (Civil Engineering Component) 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 2E8 Materials (Civil Engineering Component) Section A.3 Hardened Concrete Properties 3.Durability Durability of concrete is its resistance to weathering, chemical attack, abrasion, frost and fire. Full compaction Proper curing Low water content High cement content Permeability should be as low as possible and is improved by;

17 2E8 Materials (Civil Engineering Component) 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 2E8 Materials (Civil Engineering Component) Section A.3 Hardened Concrete Properties 3.Durability Chloride Attack 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 Slow process dependent on permeability

19 2E8 Materials (Civil Engineering Component) 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 2E8 Materials (Civil Engineering Component) 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 2E8 Materials (Civil Engineering Component) Section A.3 Hardened Concrete Properties 3.Durability Fire Resistance Concrete is non-flammable Low thermal conductivity

22 2E8 Materials (Civil Engineering Component) Section A.3 Hardened Concrete Properties 4.Cube/Cylinder Manufacture & Testing

23 2E8 Materials (Civil Engineering Component) Section A.3 Hardened Concrete Properties 4.Cube/Cylinder Manufacture & Testing

24 2E8 Materials (Civil Engineering Component) Section A.3 Hardened Concrete Properties 5.Cube Failures

25 2E8 Materials (Civil Engineering Component) Section A.3 Hardened Concrete Properties 5.Cube Failures

26 2E8 Materials (Civil Engineering Component) 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/mm 2 (GPa)

27 2E8 Materials (Civil Engineering Component) Section A.3 Hardened Concrete Properties 6.Young’s Modulus & Poisson’s Ratio

28 2E8 Materials (Civil Engineering Component) Section A.3 Hardened Concrete Properties 6.Young’s Modulus & Poisson’s Ratio

29 2E8 Materials (Civil Engineering Component) Section A.3 Hardened Concrete Properties 6.Young’s Modulus & Poisson’s Ratio

30 2E8 Materials (Civil Engineering Component) Section A.3 Hardened Concrete Properties 6.Young’s Modulus & Poisson’s Ratio  = -  trans /  longitudinal For Concrete Poisson’s Ratio is taken as 0.2. The phenomenon explains why cubes fail in compression.

31 2E8 Materials (Civil Engineering Component) 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 2E8 Materials (Civil Engineering Component) 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 2E8 Materials (Civil Engineering Component) Section A.3 Hardened Concrete Properties 7.Drying Shrinkage

34 2E8 Materials (Civil Engineering Component) 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 2E8 Materials (Civil Engineering Component) Section A.3 Hardened Concrete Properties 8.Creep

36 2E8 Materials (Civil Engineering Component) Section A.3 Hardened Concrete Properties 8.Creep Takes place over many months Elastic Recovery Restrained by Reinforcement

37 2E8 Materials (Civil Engineering Component) Section A.3 Hardened Concrete Properties 8.Creep

38 2E8 Materials (Civil Engineering Component) 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 / o C


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