1. When the ____________ content is low, most ettringite will be formed in the plastic state.
a) C3SS
b) C3AA
c) C2S
d) C4AF
Explanation: When the C3A content is low, most ettringite will be formed in the plastic state.
2. The philosophy of prescribing low ____________ cement to improve resistance to sulphate attack.
a) C3S
b) C3A
c) C2S
d) C4AF
Explanation: The philosophy of prescribing low C3A cement to improve resistance to sulphate attack hinges on the need to minimize ettringite formation after the concrete hardens.
3. The quality of concrete, specifically a ____________ permeability, is the best protection against sulphate attack.
a) High
b) Medium
c) Low
d) Very low
Explanation: The quality of concrete, specifically a low permeability, is the best protection against sulphate attack.
4. For concrete exposed to a very aggressive environment the w/c should be lower than __________
a) 1
b) .5
c) .4
d) .8
Explanation: Higher is the aggressiveness of the environment lower should be the w/c ratio. For concrete exposed to a very aggressive environment, the w/c should be lower than 0.40.
5. The quality of concrete, specifically a ____________ w/c ratio, is the best protection against sulphate attack.
a) High
b) Medium
c) Low
d) Very low
Explanation: The quality of concrete, specifically a low w/c ratio, is the best protection against sulphate attack.
6. The quality of concrete, specifically a ____________ cement content, is the best protection against sulphate attack.
a) High
b) Medium
c) Low
d) Very low
Explanation: The quality of concrete, specifically a high cement content, is the best protection against sulphate attack.
7. Concentration of water-soluble sulphates in water ___________ ppm for mild exposure.
a) <150
b) 150-1500
c) 150-10000
d) >10000
Explanation: Concentration of water-soluble sulphates in water less than 150 ppm for mild exposure.
8. Concentration of water-soluble sulphates in water ___________ ppm for severe exposure.
a) <150
b) 150-1500
c) 150-10000
d) >10000
Explanation: Concentration of water-soluble sulphates in water 150-10000 ppm for severe exposure.
9. The breaking up of cohesion in a mass of concrete is called ________
a) Workability
b) Segregation
c) Bleeding
d) Creep
Explanation: Segregation in concrete is commonly thought as separation of some size groups of aggregates from cement mortar in isolated locations with corresponding deficiencies of these materials in other locations.
10. The separation of water or water-cement mixture from the freshly mixed concrete is known as bleeding.
a) True
b) False
Explanation: The separation of water or water-cement mixture from the freshly mixed concrete is known as bleeding.