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

2. Schedule Lectures: Tutorials: Concrete Laboratory:
Weeks 1-3(Wed 3-5): Timber, aluminium, glass and pre-cast
Weeks 4-9(Mon 10-11, Fri 3-4): Concrete, reinforced concrete and pre-stressed concrete
Tutorials:
Alternate weeks, weeks 4-9, Thursday 5-6pm, commencing Groups 1-20 in week 4 of term, in Joly Theatre
Concrete Laboratory:
Each laboratory group on either Monday or Thursday, for one week only, as per timetable

3. 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:

4. What is Concrete?
Concrete is the most widely used construction material in the world
Concrete is a construction material composed of crushed rock or gravel and sand bound together with a hardened paste of cement and water.

5. Concrete History

6. Concrete History
Aquaducts

7. Concrete History
Colleseum

8. Concrete History
Pantheon

9. Concrete History
Eddystone Lighthouse – John Smeaton (1756)

10. Concrete History
Joseph Aspdin Patent (1824)

11. Concrete History
Reinforced Concrete Flower Pot (Joseph Monier 1867)

12. Concrete History
Weavers Mill Swansea (1898)

13. Concrete History
Freysinnet

14. Concrete History
Hoover Dam

15. Concrete History
Astrodome

16. Concrete History
Toronto Tower

17. Section A.1 Basic Materials
1. Cement
2. Water
3. Aggregates
4. Admixtures

18. Specialised Portland Cements:
Section A.1 Basic Materials
1. Cement
Ordinary Portland Cement (OPC)
Rapid Hardening Portland Cement (RHPC)
Sulphate Resistant Portland Cement (SRPC)
White Portland Cement (WPC)
Specialised Portland Cements:
Masonry Portland Cement
Low Heat Portland Cement
Hydrophobic Portland Cement
Oil-well Portland Cement

19. Alternative Cement Replacement Materials
Blastfurnace Slag Cement (GGBS)
Pulverised-fuel Ash Cement (PFA)
Metakaolin
Rice Husk Ash
Silica Fume
Cements in Europe are classed as CEM1 (OPC or RHPC), CEM2-4 (OPC with limestone, PFA or GGBS) in varying proportions pre-blended

20. Section A.1 Basic Materials
1. Cement
Chemistry of OPC

21. Section A.1 Basic Materials
1. Cement
Manufacture

22. Section A.1 Basic Materials
1. Cement Manufacture

23. Section A.1 Basic Materials
1. Cement
Sulphate Resistant Portland Cement
Low triacalcium aluminate content (C3A)
Achieved by adding Iron oxide to decrease aluminate proportions
Resistant to sulphates but not resistant to strong acids
Reduced early heat

24. Section A.1 Basic Materials
1. Cement
Pulverised-fuel ash cements (latent hydraulic binder)
From burning pulverised coal in power station furnaces
Reacts with calcium hydroxide (lime) to from cementitious material
Resistant to sulphates but not resistant to strong acids
Reduced early heat of hydration
Reduced early age strength

25. Section A.1 Basic Materials
1. Cement
Blastfurnace Slag Cements (latent hydraulic binder)
By-product of iron smelting, quenched slag forms granuels
Generally blended with OPC up to 35%
Reduced early age strength
Reduced early heat of hydration

26. Section A.1 Basic Materials

27. Section A.1 Basic Materials

28. Section A.1 Basic Materials

29. Section A.1 Basic Materials
1. Cement
Delivery & Storage
Usually packaged in 25kg bags or transported in bulk tankers
Retail price €5
“Warehouse set”

30. Section A.1 Basic Materials
2. Water
Should be free from impurities
Unsuitable if it contains - sugars
- sulphates
- chlorides
Sea water must not be used for reinforced concrete

31. Section A.1 Basic Materials
Hydration
Setting and hardening results from a chemical reaction between the cement and the water, not from a drying process.
The reaction is exothermic and is irreversible. The heat produced is known as the “Heat of Hydration” C3A and C3S are the compounds primarily responsible.
The paste is usually workable up to two hours before it begins to harden
Strength gain is initially rapid becoming progressively less rapid
Strength gain continues indefinitely provided moisture is present. “Curing”

32. Section A.2 Fresh Concrete Properties
2. Cement hydration
Cement + H2O = Calcium Silicate Hydrate (C-S-H) +Ca (OH)2 +H2O

33. Section A.2 Fresh Concrete Properties
2. Cement hydration and heat generation

34. Section A.1 Basic Materials
2. Cement paste strength gain

35. Section A.1 Basic Materials
3. Aggregates
Gravels, crushed rock and sands that are mixed with cement and water to produce concrete.
Coarse aggregates are those that do not pass through a 5mm sieve.
Fine aggregates are those that pass through a 5mm sieve.
Generally make from 50% to 80% of the concrete mix.
Used to reduce cost and modify and imporve properties like strength and drying shrinkage.

36. Section A.1 Basic Materials
3. Aggregates
Quality Requirements
Durability - Hard
- Adequate Strength
- No deletrious material
Cleanliness - free from chemical impurities
- free from organic material
- free from dust
- excessive washing is not the answer
- avoid silica acid aggregates.

37. Section A.1 Basic Materials
3. Aggregates
Aggregate Types
Normal density - Most gravels and crushed rock
- Divided into coarse and fine
Lightweight - Weak porous solids
- Good thermal properties
High Density - radioactive screening

38. Section A.1 Basic Materials
3. Aggregates
Sieve Analysis

39. Section A.1 Basic Materials
4. Admixtures
Additives to the concrete mix to improve certain properties
Must be used with care as excessive amounts can have adverse effects on the concrete

40. Section A.1 Basic Materials
4. Admixtures
Accelerators
Increases the rate of strength gain at an early age
Most common is calcium chloride (CaCl) but may corrode steel
Most common is calcium chloride (CaCl) but may corrode steel
Does not increase final strength

41. Section A.1 Basic Materials
4. Admixtures
Water Reducing Admixtures (Plasticisers)
Reduces the amount of water required for a given workability
Most common is calcium ligno-sulphate
Reduces the risk of evaporation cracks
Air Entraining Admixtures
Generates evenly dispersed air bubbles in the mix
Improves durability against frost and marine environments
Volume or air entrainment should not exceed 13% of cement paste

42. Section A.1 Basic Materials
4. Admixtures
Retarding Agents
Reduces the rate of evolution of heat
Necessary for very large concrete pours
Water-repelling admixtures
Can improve impermeability of concrete in basements and water retaining structures
No substitute for sound concrete

43. Section A.1 Basic Materials
4. Admixtures

44. Section A.1 Basic Materials
Admixtures
Foaming Agents
Produces highly flowing light concrete
Superplasticiser
Produces flowing normal concrete with high strength
Self-compacting
Allows highly flowing cohesive mix with no need for vibration. It can also be self-levelling.