asasas

1. BLD62003 Building Materials
Tutorial 3 Presentation
Thun Shao Xun 0315919
Muhd. Hasif 0316413
Clement Lim 0321702
Shane Sim 0321288

2. Compacting Factor Test
What?
- To determine the workability of freshly
mixed concrete.

4. How?
1. Concrete and water cement is mixed into upper
hopper. Concrete excess must be levelled
accordingly.
2. The trap door of upper hopper is opened in order
for the concrete to fall into the lower hopper.
3. The trap door of lower hopper is opened for the
concrete to fall into the cylinder
4. The remaining concrete which remains above the
top level of cylinder is cut off by plane blades.

5. 5. The concrete in the cylinder is weighed and labeled as
partially compacted concrete.
6. Fresh sample of concrete is filled into the cylinder and
vibrated until it is fully compacted.
7. It is then weighed and labeled as fully compacted
concrete.

6. Method of calculation
Consistency Compacting Factor
Very Dry 0.70
Very Hard 0.78
Hard 0.85
Plastic Hard 0.89
Plastic 0.92
Liquid 0.95
High Liquid 1.00

7. THE FACTORS
AFFECTING WORKABILITY
AND
STRENGTH OF CONCRETE

8. First Factor:
Aggregate / Cement Ratio
If the volume remains the same and the proportion of
cement in relation to that of sand is increased the
surface area of the solid will increase.
If the surface area of the solids has increased, the water
demand will stay the same for the constant workability.
Assuming an increase in cement content for no increase
in water demand, the water cement ratio will decrease.
If the water cement ratio reduces, the strength of the
concrete will increase.

9. The influence of cement content on workability and strength is an important
one to remember and can be summarized as follows:
1. For a given workability an increase in
the proportion of cement in a mix has
little effect on the water demand and
results in a reduction in the
water/cement ratio.
2. The reduction in water/cement ratio
leads to an increase in strength of
concrete.
3. Therefore, for a given workability an
increase in the cement content results
in an increase in strength of concrete.

10. Second Factor:
Relative Humidity
If the concrete is allowed to dry out, the hydration
reaction will stop. The hydration reaction cannot
proceed without moisture. The three curves
shows the strength development of similar
concretes exposed to different conditions.

12. Third Factor:
Compaction of Concrete
• elimination of voids from the concrete.
• the process - compaction - increases strength
of concrete by 30%

13. How?
• Manually - Rodding
• Mechanically - Vibration

14. Result
?
• Less Compaction - Honey Comb Concrete
• Over Compaction - Segregation of Concrete

15. Admixtures of Concrete
Shrinkage Reducing
Super Plasticizer
Corrosion Inhibitor

16. SHRINKAGE REDUCING

17. Function?
reduced drying shrinkage in water.

18. How?
Capillary Pores
PROBLEM
- Excess water begin to evaporate.
- Capillary pores formed.
- Water within have high surface
tensions.
- Force tends to close the pores.
- Volume reduced and let to shrinkage.
IF USE ADMIXTURE
- Reduce water surface tension effect
- Reduce shrinkage as water
evaporates

19. Advantages?
Significantly reduces drying shrinkage by as much
as 80% at 28 days, and up to 50% at one year or
beyond when 2% MasterLife SRA 20 admixture
by mass of cement is used in the concrete
mixture.
Reduces stresses induced from one-dimensional
surface drying in concrete slabs and floors.
Reduces carbonation.

20. Advantages?(Continued)
Reduces drying shrinkage cracking and
microcracking thereby improving aesthetics,
watertightness and durability.
Reduction in drying shrinkage minimizes pre-stress
loss.
Minimizes curling.
Increase permeability.

21. Super Plasticizer

22. a type of linear polymer chemical additive
used in cement and concrete manufacturing as
high-range water reducer.
What?

23. Advantages?
make high strength concrete
(compressive strength up to 22,000
psi).
can be utilized in producing flowing
concrete used in a heavy reinforced
structure with inaccessible areas.

24. Advantages?(Continued)
Concrete early strength enhancement (50 to
75%).
Does not significantly affect surface tension of
water and does not entrain a significant amount
of air.

25. loss of workability as a result of rapid slump
loss and incompatibility of cement and super
plasticizers.
Disadvantages
?

26. Sulfonated melamine
Sulfonated Napthalene
Modified Lignosulfonates
Types?
A combination of high dosages of water
reducing and accelerating admixtures

27. Corrosion Inhibitor

28. Chemical compound.
Usually react with metallic surface.
Layer to protect the material such as reinforcing
steel.
What
?

29. Advantages?
Reduces the rate at which chlorides and moisture
enter the material.
Reduces maintenance cost.
Forms a strong and durable material.
Decreases the corrosion rate.

30. Examples?
Rheocrete 222+ (a combined waterproofer and organic
corrosion inhibitor)
Extended service life of reinforced concrete
structures
Reduces the corrosive effect of moisture and
chlorides
Easily used in elevated temperatures

31. Bridge Corrosion

32. Corrosion Inhibitor