Assignment 3 : Chemical admixtures and
reinforcement Q&A
1.Chemical admixtures are used to (select all that apply)
Change properties of fresh or hardened concrete
Overcome poor mix design
Overcome emergencies during concrete operations
Maintain the quality of concrete - answer-Change properties of fresh or hardened concrete
Overcome emergencies during concrete operations
Maintain the quality of concrete
Which of the following admixtures is used to increase the flowability of concrete?
Air entertainers
Air detrainers
Accelerators
Superplasticizer - answer-Superplasticizer
2.Which of the following is true about air entrainers? (Select all that apply)
entrained air results in decrease in the strength of concrete
entrained air improve freeze-thaw resistance
entrained air doesn't affect the strength of concrete
entrained air doesn't affect freeze-thaw resistance - answer-Entrained air results in decrease
in the strength of concrete
Entrained air improve freeze thaw resistance
, 3.Which of the following is true about water reducers and superplasticizers?
This admix can negatively affect the durability of concrete
This admix decreases workability
This admix increases workability with increasing water content
This admix helps increase concrete strength by lowering w/c ratio - answer-This admix helps
increase concrete strength by lowering w/c ratio
4.Which of the following admixtures should be used in rebar congested areas in which
workability and vibration is a concern?
Retarders
Shrinkage reducers
Accelerator
Superplasticizer - answer-Superplasticizer
5.The effect of certain water reducers in increasing workability is short lived. This means that
a concrete mixture can lose slump in a short amount of time (~30 minutes)
True
False - answer-True
6.__________ should be used in order to offset the effect of a hot weather concreting
Accelerator
Water reducers
Set retarding
Air entrainers - answer-Set retarding
reinforcement Q&A
1.Chemical admixtures are used to (select all that apply)
Change properties of fresh or hardened concrete
Overcome poor mix design
Overcome emergencies during concrete operations
Maintain the quality of concrete - answer-Change properties of fresh or hardened concrete
Overcome emergencies during concrete operations
Maintain the quality of concrete
Which of the following admixtures is used to increase the flowability of concrete?
Air entertainers
Air detrainers
Accelerators
Superplasticizer - answer-Superplasticizer
2.Which of the following is true about air entrainers? (Select all that apply)
entrained air results in decrease in the strength of concrete
entrained air improve freeze-thaw resistance
entrained air doesn't affect the strength of concrete
entrained air doesn't affect freeze-thaw resistance - answer-Entrained air results in decrease
in the strength of concrete
Entrained air improve freeze thaw resistance
, 3.Which of the following is true about water reducers and superplasticizers?
This admix can negatively affect the durability of concrete
This admix decreases workability
This admix increases workability with increasing water content
This admix helps increase concrete strength by lowering w/c ratio - answer-This admix helps
increase concrete strength by lowering w/c ratio
4.Which of the following admixtures should be used in rebar congested areas in which
workability and vibration is a concern?
Retarders
Shrinkage reducers
Accelerator
Superplasticizer - answer-Superplasticizer
5.The effect of certain water reducers in increasing workability is short lived. This means that
a concrete mixture can lose slump in a short amount of time (~30 minutes)
True
False - answer-True
6.__________ should be used in order to offset the effect of a hot weather concreting
Accelerator
Water reducers
Set retarding
Air entrainers - answer-Set retarding
