AN EXPERIMENTAL STUDY ON SHRINKAGE BEHAVIOUR OF EARTH BRICKS REINFORCED WITH STRAW

Abstract

There is a growing interest in using earth as a building material which exhibits excellent physical properties with respect to ecological design, and fulfils all strength and serviceability requirements for thermal transmittance. In this paper a series of laboratory tests on shrinkage of earth bricks materials is presented. The brick materials consist of cohesive soil, cement, gypsum and different natural fibres. Two types of fibres, wheat and barley straw were used as reinforcement in the tests. Cement and gypsum was used as stabilized materials. The shrinkage behavior of bricks was studied by laboratory tests for different compositions. The specimens of brick material were dried under a constant temperature of 105°C respectively. The average shrinkage percentage of unfired earth bricks reinforced with wheat straw are 4.161, 2.615 and 0.573 % for the fibres contents of 0%, 1% and 3% respectively, while the shrinkage percentages for bricks reinforced with barley straw fibres are 4.161, 3.458 and 0.613 % for reinforcement fibres contents of 0%, 1% and 3% respectively. The percentages of shrinkage for bricks reinforced with barley straw fibres are 3.458, 3.51and 3.60% for cement contents of 0%, 5% and 10 % respectively. additionally, the percentages of shrinkage for bricks reinforced with barley straw fibres are 3.458, 3.677 and 3.829% for gypsum contents of 0%, 5% and 10 % respectively. The results revealed that fibres content have greater effect on shrinkage behaviour than gypsum and cement content.