WHAT IS WATER CEMENT RATIO?
The water–cement ratio is the ratio of the weight of water to the weight of cement used in a concrete mix.
EFFECT OF WATER CEMENT RATIO ON CONCRETE
A lower ratio leads to higher strength and durability, but may make the mix difficult to work with and form. Work-ability can be resolved with the use of plasticizers or super-plasticizers.
However, a mix with a ratio of 0.35 may not mix thoroughly, and may not flow well enough to be placed. More water is therefore used than is technically necessary to react with cement. Water–cement ratios of 0.45 to 0.60 are more typically used. For higher-strength concrete, lower ratios are used, along with a plasticizer to increase flowability.
Too much water will result in segregation of the sand and aggregate components from the cement paste. Also, water that is not consumed by the hydration reaction may leave concrete as it hardens, resulting in microscopic pores (bleeding) that will reduce final strength of concrete. A mix with too much water will experience more shrinkage as excess water leaves, resulting in internal cracks and visible fractures (particularly around inside corners), which again will reduce the final strength.
Subscribe & Watch Technical video’s related to civil engineering on our YouTube channel We Civil Engineers