Suitability of Quarry Dust as Fine Aggregates in Concrete: A Case of Ndolela Quarry in Iringa Tanzania

Abstract

The main objective of this research was to test the suitability of using the quarry dust as fine aggregates in concrete. The study wanted to investigate the properties of fresh and hardened concrete that contains quarry dust as fine aggregates. The quarry dust to be investigated was collected from Ndolela quarry site, found at Isimani village in Iringa region Tanzania. The area constitutes plenty of quarry dust lying idle and the soil found in the same area is clay, the soil that is not suitable for construction. First the properties of the quarry dust such as bulk and gross density, fineness modulus and gradation were determined. Thereafter the concrete mix with sand only as fine aggregates (control concrete mix) was prepared and their properties compared with three different concrete mixes containing quarry dust as fine aggregates. The first, second and third mix had sand replaced by 25%, 50% and 75% respectively. The resulting concrete cubes were tested at seven days and twenty-eight days. The concrete cubes with sand replaced with quarry dust by 75% showed excellent results in compressive strength aspect. Both seven day old cubes and twenty-eight day old cubes posted best compressive strength result for 75% sand replacement. Cubes with 25% and 50% sand replacement performed poorly compared to the control mix cubes. The workability of fresh concrete with quarry dust was slightly low compared to the control mix. However, this is does not rule out the quarry dust as fine aggregates; as the results still lied within the desired medium workability range of 30-80mm.  From the results of tests on fresh and hardened concrete; it was found that the quarry dust is suitable to be used as fine aggregates in concrete manufacture.