Strength and stress-strain characteristics of coir fibre reinforced cement stabilised rammed earth

Rammed earth is a monolithic construction that involves dynamically compacting processed soil in progressive layers in a rigid formwork. Cement stabilised rammed earth (CSRE) is used for the construction of load bearing walls in buildings. CSRE walls predominantly undergo sudden catastrophic shear failure under compressive loading. Fibre reinforced composites show high ductility under compression and shear avoiding the sudden catastrophic failures of the structural elements. Hence, the present investigation was focused on the behaviour of coir fibre reinforced cement stabilised rammed earth. The influence of fibre volume fraction and moisture content at the time of testing on the strength and stress strain relationships of CSRE were examined and compared. The variables considered include fibre volume fraction, moisture content at the time of testing for a given dry density, cement content and fibre aspect ratio. The strength and stress-strain relationships of CSRE with and without fibres were measured. The results show about 30-40% increase in compressive strength of fibre reinforced CSRE when compared to the unreinforced rammed earth. The stress-strain curves show large energy absorption capacity for fibre reinforced CSRE. The moisture content of the specimen during testing significantly influence the characteristics of fibre reinforced CSRE. Coir fibres can be used for improving the strength and ductility of the rammed earth.