Calcined termite hill clay powder: as partial cement replacement in production of c-25 grade concrete

Abstract

Cement is one of the components of concrete plays a great role in the construction industry, nevertheless, it is the most expensive and environmentally unfriendly material. Therefore, requirements for economical and more environmental-friendly cementing materials have extended interest in other cementing materials that can be used as partial replacement of the normal Portland cement. This research was, conducted to examine the suitability of calcined termite hill clay powder as a cement replacing material in the production of C-25 grade concrete as relief for this problem. Termite Hill Clay sample was collected from Bokuluboma vicinity. The sample was calcined at the temperature of 650 o C using muffle furnace, ground to the fineness of 150 µm and its chemical composition were investigated. Normal consistency and setting time of the pastes containing ordinary Portland cement and calcined termite hill clay powder from 0% to 40% replacement in 5% increment percentage were investigated. The compressive strength of eight different concrete mixes with the CTHCP replacing the ordinary Portland cement were prepared for 22MPa and 34MPa (i.e., for 7 th and 28 th days targeted compressive strength) concrete with water to cement ratio of 0.5 and 360kg/m 3 cement content. The properties of these mixes have then been assessed both at the fresh and hardened state. And, the study revealed that calcined termite hill clay powder was found pozzolanic and can partially replace cement. It has shown that up to 11.3% replacement of the ordinary Portland cement by CTHCP, the cubes achieved a target mean compressive strength of C-25 grade concrete at 28 th day 34Mpa. Although, the replacement percentage greater than 11.3% of the cement by calcined termite hill clay powder in the concrete has shown a slightly lower compressive strength. Moreover, the mix was found workable up to 25% replacement percentage and also the setting time of the pastes containing calcined termite hill clay powder found faster than that of the control mix. Finally, it can be concluded that CTHCP was suitable to partial replace cement, 11.3% replacement of cement by calcined termite hill clay powder was optimal percentage for the production of C-25 grade concrete, the mix was workable up to 25% replacement and this mineral admixture found set accelerator suitable for cold weather concreting.