WORKABILITY AND COMPRESSIVE STRENGTH OF CONCRETE CONTAINING PARTIAL REPLACEMENT OF ORDINARY PORTLAND CEMENT BY SELECTED SUPPLEMENTARY CEMENTITIOUS MATERIALS

Abstract

This research work investigated the work-ability and compressive strength of concrete containing partial replacement of ordinary Portland cement by selected supplementary cementitious materials (SCMs), namely granulated cupola furnace slag, Abakaliki rice husk ash and coconut husk ash. Chemical analysis of these three SCMs was performed. Standard consistency test, setting time test and fineness test were conducted on the cement paste blended with the SCMs. Natural moisture content test, sieve analysis, bulk density test and specific gravity test were also conducted on these three SCMs and aggregates, to determine the suitability of the materials for concrete making. The air entrainment test revealed that partial replacement of ordinary Portland cement with these SCMs at 5%, 10% and 15% made the resulting concrete less porous. The results obtained from the slump and compacting factor tests showed that introduction of the SCMs reduced the workability of the fresh concrete. Maximum compressive strength was attained with optimum replacement of cement by granulated cupola furnace slag at 15% with a value of 29.8 N/mm2, giving 31.9% rise over the control. Maximum compressive strength was also attained with optimum replacement of cement by Abakaliki rice husk ash at 10% with a value of 25.0 N/mm2, giving 10.6% rise over the control. Maximum compressive strength was attained with optimum replacement of cement by coconut husk ash at 15% with a value of 24.6 N/mm2, giving 8.8% rise over the control. From the cost analysis, there was gain in price of ₦1,000.00 when Elephant brand of ordinary Portland cement was partially replaced by 15% granulated cupola furnace slag for one cubic meter of concrete, giving 4% reduction in price for 15% granulated cupola furnace slag replacement over the control. The results revealed that these three materials satisfied the relevant ASTM, BS and IS codes. Therefore, they are good supplementary cementitious materials.