Effect of sorghum husk ash and calcium chloride on compressive strength of grade 20 concrete

This study examined the influence of sorghum husk ash (SHA) and calcium chloride (CaCl 2 ) as fractional substitution of cement in grade 20 concrete. Sorghum husk Ash (SHA) was gotten by burning of sorghum husk at a regulated temperature. The substitution of cement by SHA were 0, 5, 10, 15, 20 and 25%. A fixed amount of 1% CaCl 2 was mixed with Cement/SHA in all the test samples apart from control mixture. Sample sizes of 150 x 150 x 150 mm concrete cubes were cast and healed in water respectively for 7 as well as 28 days. The tests carried out on prepared fresh and hardened concrete were slump and compressive strength. The result of slump showed that the concrete turn out to be stiffer with increase in proportion of SHA. The 28 day compressive strengths result shows that 5%SHA/1%CaCl 2 have the maximum strength of 26.45 N/mm 2 followed by 10% (25.01 N/mm 2 ), 0%SHA/1%CaCl 2 (23.11 N/mm 2 ), 15%SHA/1%CaCl 2 (22.45 N/mm 2 ), 20%SHA/1%CaCl 2 (20.90 N/mm 2 ) and 25%SHA/1%CaCl 2 (18.13 N/mm 2 ). This implies that the best addition of SHA/CaCl 2 as fractional substitution for cement in concrete is in the range 0 - 20% since their compressive strength results were above 20 N/mm 2 specified for grade 20 concrete. Incorporation of 5%SHA/1%CaCl 2 and 10%SHA/1%CaCl 2 substitution would yield a concrete of greater compressive strength than standard grade 20 concrete.