The strength behaviour of lime-stabilised plastic fibre-reinforced clayey soil

This paper studies the effect of lime and discrete plastic fibre on the strength and stiffness behaviour of clayey soil. A series of unconfined compressive strength (UCS), split-tensile strength (STS) and California bearing ratio (CBR) tests are performed on clayey soil with different percentage of lime (i.e. 3%, 5% and 9% by dry weight of soil) and fibre (i.e. 0.5%, 1%, 1.5% and 2% by dry weight of soil) at different curing periods (i.e. 7, 14 and 28 days). The results show that the addition of lime improved the compressive and tensile strength of the soil up to 5% of lime beyond which it decreases. The role of fibre on lime-stabilised soil is found to be more significant than that of fibre-reinforced soil. The inclusion of fibre within lime-stabilised soil helps to increase the peak axial stress, achieve the residual strength, increase the modulus of elasticity and toughness, and change the failure mode of lime-stabilised soil from completely brittle to ductile. The improvement of UCS and STS is about 6.7 and 20 times than that of the parent soil, respectively. The maximum rate of improvement of strength occurs within 7 days of curing, and after that the effect of curing is marginal. Irrespective of lime and fibre content, good correlations are established between UCS with modulus of elasticity (E-50) and STS of lime-stabilised fibre-reinforced soil. Furthermore, the addition of fibre improved the CBR and secant modulus value of lime-stabilised soil which reduced the thickness of pavement and hence reduces the cost of construction.