Concrete @ your Fingertips

Excess or added water to concrete

The key to achieving durable and quality concrete is the control of the constituent materials, both physical properties and quantities. Particularly important is the water content in relation to the cement content i.e. w/c ratio. What has always been prohibited in quality concrete production is the abuse of the addition of extra water to increase workability above the permitted tolerance. This practice increases the free w/c ratio above the designed values and if excessive invariably leads to sub-standard strength and durability.

10 litres of water added per cubic metre can reduce the strength by 3MPa.

This action may manifest itself as an unacceptable surface finish (poor or inconsistent retention of brush marks or tamps), resulting from an increased susceptibility to bleeding and segregation. Problems that can be caused by the addition of excess water include, settlement cracks, weak surface (poor abrasion resistance), dusting, poor freeze-thaw resistance, low structural strength etc.