Civil Engineering - Building Materials - Discussion

Any one please elaborate why there is a need of higher w/c ratio in case of underwater concreting?

Since the structure is already under water so the heat of hydration that gets generated will be taken care of by the curing water itself.

Please correct me if I am wrong.

I have one doubt, water cement ratio of m20 concrete is 0.55. My question is 0.55 means how many bags of cement and how many bags of water we should use. Please anyone can answered my doubt?

The reason for high w/c in massive concrete under water is due mainly on work ability. Practically most of the concrete work under water need casing, and for proper compaction to be achieved the poured concrete has to be self compacted.

Why massive concrete structures which remain continuously under water w/c ratio is high as compare to drying & wetting concrete structure?

Can any one keep reference for above mentioned W/C ratios?

On high workability it easy to work on those concrete. So we use more water cement like 0.55 or 0.65.

In water, the thin like structure require 0.55 wc ratio. Why it is increasing in water every structure will given high wc ratio from a supposed one.

The reaction of cement with water is exothermic and releases lot of heat. This heat is very high in case of mass concrete structures which in turn results in failure.

So high W/C ratio is used for both workability during construction and serviceability during operation.

AS W/C Ratio increases strength decreases right then how can we use those high ratios at important places ?

The cement:mortar ratio is important in prac engineering work because cement features, precast or not, need a specific ratio to suit its specific function. Say for instance you're building a brick wall which has an opening; your c:m ratio (the first number represents one "part" cement in my country, and the latter represents aggregates such as sand, stones etc) between the bricks which a situated above the opening must be in such a way that it is stronger than the cm of the surrounding bricks.