Effect of Replacement of Natural Sand by Grit on Workability of Concrete

Globally the construction industry is facing a major difficulty in obtaining natural river sand for making concrete. At national level the scenario is not different than global problem of natural sand. Day by day the sources of natural sand is depleting at a very fast rate and at the other end requirement of concrete is increasing tremendously due to infrastructure developments taking place worldwide. Government has also taken a serious note of the depleting sources of natural sand and is taking a corrective step to protect the environment. River sand is expensive because it is rare to find at every location, at the same time it is required to be transported from long distances ultimately increasing its final cost. Environmental issues and other constraints pose difficulties in availability and use of river sand. To cope up with this global problem and to reduce the pressure on natural resources, one of the alternatives is to replace the natural sand partially or fully by other such materials without compromising the quality of concrete. This has led to a search for different substitute materials for natural sand. Either partial or full replacement of natural sand by other alternative materials like grit, stone dust, manufactured sand, foundry sand or other such materials are being researched. One of the easily available materials is grit which can be obtained from stone crushers and can be used as a substitute material to natural river sand.Natural sand plays an important role in the performance behaviour of concrete which directly affects the mix design. Natural sand is rounded and smooth which improves the workability of concrete. However, the grit is angular and rough which adversely affects the workability. There is a challenge before construction industry to use such material without compromising on properties of concrete. In this paper an attempt has been made to propose a mix proportion for producing concrete using grit as a substitute material to natural sand. The experimental work was carried out to study the effect of grit on workability characteristics of concrete. The results obtained from the study shows that grit can be used successfully by partially replacing the natural sand thus effectively reducing the load on environment.