INGREDIENTS OF CONCRETE

INGREDIENTS OF CONCRETE

   

    

  Cement, Aggregate, water are the ingredients of concrete. Aggregate may be fine aggregates as sand or coarse aggregates as gravel and crushed stones 

• Cement
• Aggregates 
• Water 

Cement 

Cement is used as the binding material and acts as a binder for coarse and dine aggregates. Generally ordinary portland, cement is used to form concrete, Initial setting time of good cement should not be less than 30 minutes and final setting times should not exceed 10 hours.

Aggregates 

 The granular materials generally inert chemically such as natural sand, gravels, crushed stones and air cooled iron blast furnace slag, are called aggregates. If only cement is used for the construction, the concrete will result in shrinkage and ultimately cracks are develop. So as to avoid these cracks, aggregates are used. These aggregates are bound together by means of cement. The aggregates are classified into two categories such as fine and coarse aggregates. The material which is passed through sieve no. 480 is called fine aggregates and which retained on sieve no. 480 is called coarse aggregates. These aggregates should be clean. sharp, angular, well graded, hard durable and free from foreign matters.

Water

  The water to be used in making concrete should confirm to the drinking water standard. It is least expensive but most important ingredient of concrete. The water, which is used for making concrete should be free from acids, alkalies, salts, oil, grease and decayed vegetable matters. The amount of water should be of that, which will produce concrete of required quality.

Proportion Ingredients for concrete 

 The best concrete can be obtained by mixing the ingredients in correct proportion. Proportioning of ingredients can be done by trail so as in this procedure weigh the ingredients of concrete and mix them to the same consistency as it is required in the work =. Ingredients for concrete are fine aggregates, coarse aggregates, cement and water. The ingredients are depends upon the nature of the work and availability of materials. Gradation of coarse and fine aggregates affects the solidity of cement concrete. A cement concrete having good proportions of aggregates and cement will have solidity between 0.80 to 0.84. For the same coarse and fine aggregates, the strongest concrete is that which contains greatest percent of cement in a unit volume of concrete as well as for the same percent of cement and the same aggregates. The strongest concrete is that which gives greatest solidity. The ideal proportion of the concrete will be that, which produces greatest strength and solidity at the least cost. In estimating the quantities of ingredients for cement concrete it should be kept in mind that voids in coarse aggregates are fill up by sand and voids in fine aggregates are fill up by  sand and voids in fine aggregates are fill up by cement. So as the total increase in the volume of the concrete will slightly increase the quantity of coarse aggregates.