GAP GRADING OF AGGREGATES & ITS EFFECT ON THE INHERENT PROPERTIES OF CONCRETE

Abstract

Aggregate are one of the most important constituent of concrete. They provide the body to the concrete, help in reducing shrinkage and greatly affect economy. Earlier, they were considered chemically inert but as of now, it has been established that some of these aggregates are chemically active and exhibit chemical bond at the interface of aggregate and cement matrix. The simple fact that they occupy almost 70-80% of the overall volume of concrete, merits the statement that their impact on various characteristics of fresh and hardened concrete is undoubtedly considerable. In this study, emphasis is given on the different types of gradation of aggregates and their influence on the properties of concrete. Standard grading curves as proposed by Gambhir, 2004 are studied in detail to understand the behavior of coarse and fine aggregates. Gap grading is a relatively new term as far as traditional methods of combining aggregates are concerned. Three different batches were cast, using samples of well graded, uniformly graded & gap graded aggregates, for M20 grade of concrete. Various tests were carried out to evaluate the effect of grading of aggregate on the inherent properties of fresh and hardened concrete.