Assessment of Rice Husk Ash (RHA) and Calcium Chloride (CaCl2) on Compressive Strength of Concrete Grade 20

This research assessed the effect of Nigerian rice husk ash (RHA) and calcium chloride (CaCl2) as partial replacement of cement in concrete grade 20. Rice husk ash (RHA) is obtained by combustion of rice husk in a controlled temperature. The replacement of OPC with rice husk ash (RHA) were 0%, 5%, 10%, 15% and 20%. 1% of Calcium Chloride was blended with OPC/RHA in all the test specimens except from control mix. Concrete cubes of sizes 150mm x 150mm x 150mm were cast and cured in water for 7, 14 and 28 days respectively. Slump test was conducted on fresh concrete while density test and compressive strength test were conducted on hardened concrete. The slump results revealed that the concrete becomes less workable (stiff) as percentage increases. The compressive strength result at 28 days revealed that 5%RHA/1%CaCl2 have the highest strength of 26.82N/mm(2) while 20%RHA/1%CaCl2 have the lowest strength (21.48N/mm(2)). Integration of 5%RHA/1%CaCl2 and 10%RHA/1%CaCl2 as cement replacement will produce a concrete of higher compressive strength compared to conventional concrete in grade 20 concrete.