The potential of calcium carbide waste and termite mound soil as materials in the production of unfired clay bricks

Abstract

This study investigated the physical, mechanical, thermal and microstructural properties of calcium carbide residue (CC) with chemical admixture (CA) stabilised clay bricks from termite mound clay soil (TMC). Four different mix ratios of B (TMC 70%+cement 30%+ CA 0.1); C (TMC 70%+cement 20%+ CC 10% + CA 0.1); D (TMC 70%+cement 10%+ CC 20% + CA 0.1) and E (TMC 70% + CC 30%+ CA 0.1) were produced, tested and the results compared with the control mix. Thermal conductivity, SEM, XRD and FTIR analyses were conducted to analyze the thermal, morphology and microstructural properties of the mixes. Initial rate of water absorption and water absorption after 2 and 24 h immersion showed that mixes B and C performed better than the rest with lower values that ranged from 12.5 to 33.3%. Dry shrinkage showed a progressive decrease as the CC content was increased from 10 to 20% in mixes C and D. Wet and dry compressive strengths had optimum performance at 4.33 and 17 MPa respectively for mixes with higher content of cement. The compressive strengths of mixes B, C, D and E fulfilled the minimum criteria of some building standards in some selected developing countries. SEM, XRD and FTIR analyses established that the use of varied CC content influenced the strength behaviour when added to cement and TMC. In conclusion the study has shown that incorporation of calcium carbide (10%), cement (20%) and a chemical additive (0.1) into termite mound clay soil would help in developing improved unfired clay bricks.