Potential of quarry dust and cow dung as stabilisers for black cotton soil eco-blocks for housing

Abstract

Present concerns for sustainable development have led to a revival of traditional building practices using natural or recycled resources. There is a perception that buildings constructed from such materials are environmentally benign. The use of earth on site as a building material saves manufacturing cost, time, energy, environmental pollution and transportation cost. Due to the atmospheric condition change, blocks made with black cotton soil swell, shrink and crack. This research work reports on the effect of waste material such as quarry dust and cow dung on the strength and stability of soil blocks made with black cotton soil. Black cotton soil is a soil in which there is a high content of expansive clay known as montmorillonite that forms deep cracks in drier seasons or years owing to extensive swelling and shrinkage. The shrinking and swelling of black cotton soil can significantly damage buildings and roads, leading to extensive subsidence. Accordingly, black cotton soil is never used as a construction material. The key objective of this research study was to determine the effect of various eco-friendly additives on the structural performance of black cotton soils in Kenya, and hence the potential of stabilized black cotton soil as an eco-block for buildings. Experimental work has delved into basic material properties, as well as strength tests on specimens.

Accordingly, the research work has conducted numerous tests such as atteberg limit, particle density, particle size distribution compaction test and linear shrinkage on material as well as strength test on blocks. From the results obtained, it is established that the addition of 20% quarry dust to black cotton soil increases the compressive strength of the block from 0.6 to 2.7 MPa, and with further the addition of 6% cement this value increases up to 3 MPa. The addition of Cow dung to black cotton soil reduces the number of cracks and the amount of shrinkage on blocks, and also increases the strength of the blocks from 0.6MPa to 2MPa. It is thus confirmed that the addition of quarry dust and cow-dung have significant positive effects on black cotton soil, rendering them suitable for use sustainable eco-blocks for construction.