Abstract

Pozzolans have long been established as viable materials for the partial replacement of cement in concrete. However, the extent to which they can be used is still under investigation. Pozzolans do not in themselves have cementitious value but can react chemically with calcium hydroxide and moisture to produce cementitious compounds. Pozzolanic concretes have been reported to have varied properties in term of compressive strength and durability properties which need to be ascertained. This research focuses on Calcined Termite Mound (CTM) and its influence on the compressive strength and sorptivity of concrete. Several tests were carried out to ascertain the physical, chemical, and mineralogical properties of CTM and conventional concrete constituents. Some of these tests include bulk density, setting time, aggregate crushing value (ACV), aggregate impact value (AIV), slump test, X-Ray Fluorescence (XRF), X-Ray Diffraction (XRD), sorptivity, and compressive strength tests. Compressive strength tests results for concrete containing Ordinary Portland Cement (OPC) and CTM cement blends show that CTM has higher silica content compared to OPC and can be classified as Class-N pozzolans It is also richer in calcium oxide. The study also reveals that CTM has an optimum replacement level of 5% with strength of 13.4 MPa at 28 days, which is higher than the 12.4 MPa of control concrete. Also, the result of sorptivity test for OPC-CTM blended concrete gave lower resistance to sorptivity. Regression models were developed to predict the compressive strengths of OPC-CTM concrete as a function of % replacement level and curing age.