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Civil Engineering - Building Materials - Discussion

Discussion Forum : Building Materials - Section 1 (Q.No. 5)
Building Materials
5.
Pick up the correct statement from the following:
For thin structures subjected to wetting and drying, the water cement ratio should be 0.45
For mass concrete structures subjected to wetting and drying, the water ratio should be 0.55
For thin structures which remain continuously under water, the water-cement ratio by weight should be 0.55
For massive concrete structures which remain continuously under water, the water cement ratio by weight should be 0.65
All the above.
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
21 comments Page 2 of 3.
Akhil said:   8 years ago
.65 wc ratio its bit high, and asking for segregation.
Khatri, Tejinder said:   10 years ago
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.
Bhargava reddy said:   1 decade ago
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?
ADELEKE, Abdul Waheed said:   1 decade ago
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.
Pradeep said:   1 decade ago
Why massive concrete structures which remain continuously under water w/c ratio is high as compare to drying & wetting concrete structure?
Harsha said:   1 decade ago
Can any one keep reference for above mentioned W/C ratios?
Navjot patial said:   1 decade ago
On high workability it easy to work on those concrete. So we use more water cement like 0.55 or 0.65.
Shiva said:   1 decade ago
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.
Ravi Teja trendy said:   1 decade ago
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.
Madhu c n said:   1 decade ago
AS W/C Ratio increases strength decreases right then how can we use those high ratios at important places ?
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