EFFECTS OF COMBINING METAKAOLIN AND CEMENT KILN DUST AS CEMENT REPLACEMENT MATERIAL IN CONCRETE

Abstract

Results of Compressive strength test and slump test of concrete containing Metakaolin and CKD at varying replacement levels are discussed and are compared with those obtained with the control (pure Portland cement concrete). The total partial replacement was considered in the range of 0% (i.e. control) to 50% by weight in steps of 10%. The combination for each replacement level apart from 0% are as follows: 10% (8%CKD and 2%MK), 20% (l6%CKD and 4%MK), 30% (24%CKD & 6%MK), 40% (32%CKD & 8%MK) and 50% (40% CKD and 10% MK). Cubes were cast with three mixes with varying water cement ratio; 0.55/1:1.5:3, 0.6/1:1.5/3 and 0.65/1:/1.5/3 with the aim of achieving medium strength structural grade concrete. Cubes were cured in water and tested at 7, 14 and 28 days respectively, to appreciate the strength development at each replacement value. It was observed that workability decreased with increase in replacement and that strength also decreased with increase in replacement, the best result for replacement was obtained at 10% replacement with at least 95% of the control strength. It was also observed that more than 90% of the compression strength at 28days had been attained at 14days.

Keywords

• cement kiln dust
• metakaolin
• compressive strength
• workability
• replacement
• boque’s equation