An Experimental Study to Evaluate the Properties of a Clayey Silt Treated with Lime for the Manufacture of Mud Bricks

Abstract

This work involved evaluating the properties of Cubitermes sp termite mound soil treated with 3 - 9% lime for the manufacture of adobe mud bricks and compressed earth bricks CEBs. X-Ray Diffraction and other geotechnical methods for soil characterisation were used to analyse the selected material samples. The results show that the soil is a class A-2 clayey silt with a low organic content, composed of 19.18% clay, 47.20% silt and a sand content of 23.62%. The addition of lime reduces the clay and silt content, while the sand content increases and improves the granulometry, which incorporates spindles (adobes and CEBs) with lime contents ranging from 5% to 9%. The clay content of both the raw soil and the mixes is below the 30% maximum, while the sand content of the mixes is above the 30% minimum permitted by most standards. The specific surface area SSA and cation exchange capacity CEC decrease with the addition of lime, and the mechanical properties of the material improve. Raw soil and mixes have good moulding properties and a compressive strength of CS (3.89 - 5.95 MPa) suitable for the manufacture of adobe bricks and CEBs. The microstructure shows that the soil in the Cubitermes sp termite mound is composed of kaolinite, illite, smectite, quartz, calcite and iron oxide (haematite). Kaolinite is important for making solid bricks and illite helps the soil to sinter at a relatively low temperature.