Use of Black Cotton Soil for Low Cost Buildings

A large fraction of Karnataka's population lives in black cotton (BC) soil areas. Production of bricks using black cotton soil is not possible either by the traditional brick making process or by the pressed soil block process with stabilizers. The black cotton soil blocks crack on drying. Mixing stabilisers with BC soil to press soil blocks crack on drying. Mixing stablisiers with BC soil to press soil blocks proves difficult because the clay tends to form lumps. To overcome these obstacles a project was initiated.

A successful process of black cotton soil block making was evolved. Lime was used as a stabliser because of its abundance in block cotton soil areas and its low cost. It has a reactive aspect which alters the soil properties to meet the specific engineering qualities viz., volume, stability, wet strength etc. The soil and the stabliser with a high moisture content ( 20-25% ) were kneaded together and the moulded. The block was then cured.