Earth Building in Tanzania - Use of Soil Stabilized Bricks and Blocks

Abstract

This paper presents experimental results of investigations done on the use of stabilized earth (soil) for the manufacture of bricks and blocks. The soil used was clayey sand of low plasticity. Two types of stabilizers were used to make stabilized bricks and these were cement and a combination of cement and lime. Different stabilizer proportions were employed. Results of tests carried on these bricks at 28 days indicate an optimum mix proportion of 7% cement if cement is used alone and an optimum mix proportion of 5% each if a combination of lime and cement is used as a stabilizer. With these stabilizer contents we obtain bricks of strengths of at least 2.5N/mm2 with acceptable functional capabilities in a wall for low cost housing. To make bricks comparable in strength with those made of cement and sand with a minimum strength of at least 3.5N/mm2 for load bearing walls as suggested in the Tanzania Standard, TZS 283:1986, the optimum mix proportion was found to be 8.5% cement and 7% each if cement and lime is used in combination. It is suggested that further research on the effectiveness of the various other stabilizers like bitumen, gypsum, ash/sand, and cow dung is required for the different types of soils commonly found in Tanzania. Keywords: