The main important thing in concrete design which help at site also.
W/C RATIO :
Water cemet ratio mainly affect on strength of concrete .
If you want to make concrete water is added in cement the water is required to start chemical process which is 23%.
But still fill the voids in the concrete and make gel the 15% water is added which called gel water.
Mean we totally added 38% water mean .38 W/C ratio is required
For making concrete.
If you want to make concrete with lesser W/C ratio then plasticizer (Water Reducer)or super plasticizer (High Range Water Reducer) are used help to decerese the W/C ratio.
This admixture are used in Self compacting concrete.
What happen if we increase the ratio:
The test are conducted on concrete and see that If we increase the w/c ratio of the concrete the then strength is decreasing.
And you can see in all concrete mix design if you want to make high strength concrete like M30 , M40 etc.
The water cement ratio is very low like .40 to .45
And increasing water cemet ratio by adding water also decrease the strength and make segregation and bleeding problems aries.
The role of water cement ratio is of utmost importance for the compressive strength of concrete and other desirable properties such as durability etc . Water in the concrete works in 2 ways as under :-
- it is used to hydrate the salts such as calcium oxide so as to make carbonates and silicates , which provided strength to concrete .
- In concrete , some space is occupied by the air bubbles , which reduces the strength of the concrete . For eliminating them, concrete is required to be compacted well and for that it should be workable. Water helps to make the concrete workable and helps in enhancing strength .
23 percent of water is required for hydration and 15 percent is required for making the concrete workable for ease in compaction . It comes around 38 percent . If we add more water , then it have negative effects on the proprieties of concrete.
If by some means , we are able to make the concrete workable such as by addition of plasticisers then water cement ratio can be lowered than 0.38 and properties of concrete gets improved accordingly