Question

Which ASTM cement is most appropriate for the following construction applications? What types of mineral and/or chemical admixtures could be used for each application? Give detailed reasons for your choices.

• Construction of concrete pavement (open traffic on the next day).

Answer 1

Title : Types of cement, admixture and it's applications.

For construction of concrete pavement (open traffic to next day) , Rapid hardening cement is mostly used.

As it sets faster than other types of cement, it is highly used in project where faster results are expected within short term period such as underwater works, concreting of streets or concrete pavement works.

Different admixture used for various applications are-

1.Set Retarding admixture- It is used to delay chemical reaction that takes place when concrete starts setting process. They are highly used to reduce the effect of high temperature that could faster initial setting of concrete.

These are also used in concrete pavement construction allowing more time for finishing concrete pavement, reducing additional costs to place a new concrete batch plant on job site and helps eliminate cold joints or cracks in concrete.

2.Water reducing concrete admixture- This are chemical products that when added to concrete can create desired slump at lower w/c ratio than what it is normally designed.

3.Accelerators or accelerating admixture - It is used to increase concrete strength development or to reduce concrete setting time.

4.Air entrainment admixture- This is used to increase the freeze thaw durability of concrete.

5.Shrinkage reducing admixture- This type of admixture could reduce early and long term drying shrinkage.

Conclusion: As stated initially is Rapid hardening CEMENT ( not admixture) and set retarder is an ADMIXTURE ( not a type of cement) just don't get confuse between both of this terms.

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