Stabilization of lateritic soils by extensible fibre reinforcement

Abstract

Direct shear tests were run on samples of dry laterite sand and dry laterite gravel reinforced with different types of fibres. Both natural and synthetic fibres plus copper wires were tested. Test results showed that fibre reinforcement increases the peak strength and modifies the stress-deformation behaviour of laterites in a significant manner. It increases the peak shear strength and limits the amount of post peak reduction in shear resistance. Fibres increase significantly the angle of internal friction of the composite laterite. These shear strength increases were greatest for initial fibre orientations of 0° and 60° with respect to the shear surface while 120° orientation indicates the least for a laterite. Of all the various types of fibres used, inextensible earth reinforcements (high modulus metals) give the lower shear strengths relative to the extensible ones (i.e. low modulus geotextiles). The shear strength increases from coarse sand laterite through fine gravel laterite to medium gravel laterite and the shear strength is highest when the reinforcement is installed at 50% of the depth (mid point) of the sample (shear mould).