Question 1 10 a Define consistency of a concrete mix At a g

Question 1 /10 a) Define consistency of a concrete mix. ) At a given water-cement ratio, either a change in the cement content or aggregate grading can be made to increase the consistency of a concrete mixture. Which one of the two options would you recommend? Why is it not desirable to produce concrete mixtures of a higher consistency than necessary? c) Define cohesiveness of a concrete mix. d) How do you recognize if your concrete mix has a high cohesiveness? e) Assume you need to design a concrete mix for use in highly reinforced bridge columns (i.e. bridge columns with high steel reinforcement ratios). Would a slump of 1\" be sufficient? Please explain. Unfortunately your slump turns out to be too low for highly reinforced bridge columns. How would you correct for this? f)

Solution

(1) Answer:- Consistency and workability are related to each other. Consistency is term which describes the state of fresh concrete as it is delivered to site. It refers to the ease with which the fresh can flow.

(2) Answer:- I recommend to reduces quantity of aggregate. By help of it we can increase in consistency of concrete. Higher consistency is not desirable. During placing of concrete, problem will occur.

(3) Answer:- Cohesiveness is very important property of concrete. Cohesiveness is the element of workability which indicates whether a mix is harsh, sticky or plastic.

(4) Answer:- With addition of water in a concrete mix ,Portland cement particles in a finely divided state have a tendency to flocculate showing high degree of cohesiveness.

(5) Answer:- Yes 1 inch slump value is good for bridge construction. 1 inch slump is useful for heavy mass construction.

(6) Answer:- Slump value can increase by adding water in concrete. Slump value should come in 25 mm to 30 mm for bridge design.