Comparative Cost and Strength Analysis of Cement and Aggregate Replacement Materials

Abstract

This research presents a comparative cost and strength analysis of cement and aggregate replacement materials which is aimed at reducing the cost of concrete production. Tests were performed to compare the strength and cost of seven various cement replacement materials(rice husk ash, groundnut husk ash, palm oil fuel ash, bone powder ash, acha husk ash and bambara groundnut shell ash); six aggregate replacement materials (palm kernel shell, quarrydust, crushed spent fire bricks, periwinkle shell, recycled concrete and recycled rubber  tyres) were used.Various concrete cubes of 100mm, 150mm and 225mm thickness were prepared using water/cement ratio of 0.35 and a mix design of 1:1.5:3 batching by weight was adopted. The cement and aggregate replacement materials were varied at different proportions and percentages during mixing. Samples were tested for 7, 14 and 28day strength. The following test were performed on cube samples for both physical and mechanical properties;  particle size distribution, slump test, consistency, setting time test, water absorption test, compressive strength and marshal stability test. The analysis of the results showed that bone ash cement replacement material had the highest 28day strength but the rice husk ash appears to be more promising due to its low cost and availability as well as high strength value. Compressive strength at 28 day of crushed spent fire brick aggregate as partial replacement material was higher than the conventional river sand. Periwinkle shell can only be used as light weight aggregate. The cost of using conventional aggregate can be reduced to about 30% when palm kernel shell and quarry dust are used as partial replacement for aggregate. This study suggests that; the cost of construction and concrete production can be reduced if cement and aggregate replacement materials are used.