Monday, March 30, 2009

About Concrete mix design test

Concrete is composed principally of aggregates, Portland cement, and water, and many contain other cementitious materials and/or chemical admixtures. It will contain some amount of entrapped air and may also contain purposely entrained air obtained by use of admixture or air-entraining cement.Concrete mix design has a number of different approaches such as ACI(American Concrete Institution)development in U.S.A and the most popular and widely used is the DOE method.It is the British method of concrete mix design and it is being used in the United Kingdom and other parts of the world.This method is based on extensive laboratory and field experiments carried out by the Road Research Laboratory U.K.

Water ratio is define as as the ratio of weight of water to the weight of cement, or the ratio of weight of water to the weight of cement plus added pozzolan. Either of these ratios is used in mix design and considerably controls concrete strength.When concrete is mixed many factor we consider to determine the strength,water ratio and others.Beside that we need know measure a suitable capacity for cement,aggregate and water from DOE method of mix design.

This method is applicable to normal weight concrete made with Portland cement only or taken into account ground granulated blast furnace slag or fly ash.This method does not cover the flowing concrete,pumped concrete or lightweight aggregate concrete.