RELEVANCE OF QUARRY SAND AND NATURALSAND RATIO IN ACHIEVING DIFFERENT STRENGTHS

In recent time quarry sand is being extensively used in concrete due to environmental concerns leading to restrictions on use of natural sand. The extensive research publications broadly indicate suitability as well as limitations of quarry sand use in concrete. Most of the literature relates the performance of quarry sand concrete in various combinations adopted by researchers. The need is felts by authors to identify some factors directly related to strength parameters. The authors tried ninety different combinations covering M25, M30 & M40 grade of concrete containing various amounts of cement, quarry sand, natural sand and fly ash. Authors observed that quarry sand to natural sand ratio is an important factor governing development of compressive strength, split tensile strength and flexural strength of concrete mixes consisting of quarry sand and natural sand. It has been observed that strength parameters go on increasing with quarry sand to natural sand ratio up to 0.9, there after strength goes on decreasing. The critical analysis of data compiled was used to develop mathematical models for estimating compressive strength split tensile strength and flexural strength at various ages. The models were tested for own result and result from references. It is observed that the mathematical models are realistic and justify the relevance of quarry sand to natural sand ratio in development of strength.