An Experiment to Determine the Effect of Partial Replacement of Natural Sand with Manufactured Sand on the Strength of Concrete

Abstract

Natural sand is getting depleted from the environment, because of over exploitation for construction purposes, resulting in loss of vegetation and fertile land for farming. An investigation was, therefore, conducted to determine the suitability of using manufactured sand from crushed gneisses as partial replacement for natural sand for concrete production. In the experiment natural sand was replaced with manufactured sand of the same grading as the natural sand, while keeping all other variables constant. Apart from the control concrete sample which had 100% natural sand all the other samples were treated to 10%, 20%, 30%, 40% and 50% replacement of the natural sand with manufactured sand. Concrete cubes of 150mmx150mmx150mm were made with the various proportions of cement, sand and stones in a mix ratio of 1:2:4, water -cement ratio of 0.45 and cured over 28 days.The results of compressive strength tests show that the strength of the concrete cubes with varying amounts of natural sand and manufactured sand changed marginally. This was interpreted to mean that the partial replacement of natural sand with manufactured sand up to 50% in concrete results in about 6% increase in the strength of the concrete. Manufactured sand, therefore, is regarded as suitable for concrete production on the basis of strength. However, it may affect the concrete in the long run because it contains higher amounts of deleterious substances as compared to the natural sand.

Keywords: Manufactured sand, Natural sand, Concrete, Compressive strength, Gneiss