Geotechnical Evaluation of Quarry Dust Suitability as Construction Material in Abuja and Environs

Abstract

The geotechnical properties of quarry dust (mechanical sand) from parts of Abuja and environs have been evaluated with the aim of assessing their suitability and comparative advantage over river sand in the construction. Grain size distribution, water absorption, specific gravity and compaction tests were carried out on fifteen (15) quarry dust samples using the American Society for Testing and Materials (ASTM) recommendations while compressive strength tests were conducted on hollow blocks made from quarry dust and river sand from the study area using the Portland Cement Association recommended percentages of concrete aggregates and ordinary portland cement. Rockcrete was manufactured using cement, quarry dust and rock chips in the ratio 1:2:4 and water to cement ratio of 6:10 respectively while sandcrete was manufactured using cement and river sand in the ratio 1:6 and water to cement ratio of 6:10 respectively. Grain size evaluation revealed compositional averages of sand (64.75%), gravel (27.39%) and silt (7.86%). Further evaluation of samples revealed an average water absorption of 0.96% and specific gravity of 2.60g/cm3. Compaction test revealed average maximum dry density (MDD) of 2.1g/m3 and optimum moisture content (OMC) of 6.99%. The average compressive strength of sandcrete hollow block was 0.7N/mm, 1.4N/mm, and 1.7N/mm while rockcrete hollow block showed average compressive strengths of 1.6N/mm, 2.1N/mm, and 2.3N/mm after 7, 14, and 28 days of curing respectively using ordinary portland cement. Taking study findings into consideration, quarry dust from the study area is recommended for the production of rockcrete hollow blocks using the Portland Cement Association recommended percentages of concrete aggregates and ordinary portland cement. Stakeholders in the construction sector are encouraged to use rockcrete hollow blocks due to its strength, durability, lower capillarity, and minimal humus content for growth of organics over sandcrete hollow blocks especially in the erection of high rising buildings as a strategy in addressing some structural failures arising from poor constructional materials in Nigeria.