# Civil Engineering - Building Materials - Discussion

Discussion Forum : Building Materials - Section 1 (Q.No. 5)
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.
Explanation:
No answer description is available. Let's discuss.
Discussion:
20 comments Page 1 of 2.

Strength of concrete primarily depends upon the strength of cement paste. Strength of cement paste depends upon the dilution of paste or in other words, the strength of paste increases with cement content and decreases with air and water content.

Amit Karn said:   10 years ago
The water-cement ratio is a measure of the amount of water used in a concrete mixture relative to the amount of cement. The water-cement ratio is important because it affects the strength, durability, and workability of the concrete. Different types of structures and environments may require different water-cement ratios to achieve optimal results.

For thin structures subjected to wetting and drying, such as walls and bridges, the water-cement ratio should be around 0.45. For mass concrete structures subjected to wetting and drying, such as dams and foundations, the water-cement ratio should be around 0.55.

For thin structures that remain continuously under water, such as slabs and beams, the water-cement ratio should be around 0.55. For massive concrete structures that remain continuously under water, such as piers and abutments, the water-cement ratio should be around 0.65.
(1)

Gundo said:   10 years ago
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.

Madhu c n said:   10 years ago
AS W/C Ratio increases strength decreases right then how can we use those high ratios at important places ?

Ravi Teja trendy said:   10 years 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.

Shiva said:   9 years 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.

Navjot patial said:   9 years ago
On high workability it easy to work on those concrete. So we use more water cement like 0.55 or 0.65.

Harsha said:   9 years ago
Can any one keep reference for above mentioned W/C ratios?