Development of dry plaster mix with manufactured sand

Abstract

Demand for sand has increased at present due to the rapid infrastructure development in the country. As a result of excessive extraction, natural river sand has been depleted in river basins around the country. Shortage of natural sand is a current issue in the construction industry. Therefore alternatives are used for the natural river sand. Manufactured sand (M sand) has been widely accepted as a suitable alternative for natural river sand in concrete. However, M sand is not widely used for plastering and other masonry work because of the workability issues. Therefore, this research was focused on the development of dry plaster mix with manufactured sand. Dry plaster mix could contribute significantly to increase the efficiency of construction by reducing time and wastage. In this research, performance of manufactured sand in plastering mortar and the workability properties of the mortar were evaluated in order to develop a dry plaster mix. Flow table test and the Cone penetration test were used to measure the workability of mortar. The workability is low in manufactured sand mortar compared to river sand mortar. The shear resistance is high in M sand mortar compared with river sand mortar. Therefore air entraining additives were introduced to reduce the shear resistance. Results show that the shear resistance increases about 50% from its initial value in both river sand mortar and manufactured sand mortar in two hours. Also it was observed that the workability loss is rapid when air entraining agents are present. Addition of lime improves the workability of manufactured sand mortar similar to that of river sand mortar. Results show that Cement: Lime: Sand mix ratio of 6: 2: 30 as optimum for a lime based manufactured sand dry plaster mix in order to match the workability of the same cement: sand ratio mortar mixture with river sand. Addition of lime allows retention of workability of manufactured sand mortar with time. Raw material cost is lower for lime based manufactured sand plaster compared to the river sand plaster mix.