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.