Performance of natural fiber reinforced soil blocks for earthen houses

Abstract

Soil-fibre matrix has been used for centuries for earthen house construction. The reason for using fibre might be for imparting ductility and other strength properties to the built structure. In this research work, performance of natural fibre (i.e., jute and straw) reinforced soil for earthquake resistant earthen house construction has been investigated.

Cylindrical and block specimens were prepared with and without fibre reinforcement. Uniaxial compression tests were conducted on dried specimens. Shear strength of bond mortar was also tested for block-mortar specimen. Earthen block-mortar system was prepared by pressing the dried blocks against mortar with or without jute and straw fibre. Effect of soil composition on shrinkage behavior was studied. Capacity of fibre for shrinkage control was monitored. The contribution of fibre reinforcement towards the enhancement of strength control properties was also investigated.

Test results of strength properties were compared for both unreinforced and reinforced (i.e., jute and straw fibre reinforced) soil. It was found that soil composition played the main role over the shrinkage behavior of earthen wall elements (i.e., block and mortar). Furthermore, it was observed that addition of jute fibre (2% by weight and 3 cm long) could effectively control the shrinkage crack of block and mortar. The same amount of jute fibre mixed soil proved its effectiveness over straw (1.5% by weight and 3 cm long) reinforced soil in improving strength and deformation properties of block and block- mortar. The test results revealed that earthquake resistance of earthen houses could be increased by the addition of jute fibre in both block and mortar. Based on the investigation, simple construction guidelines for jute fibre reinforced earthen house construction have also been presented.