Mechanical behaviour of fibre reinforced unsaturated clay. This investigation is to determine the improvement in the mechanical behaviour of unsaturated clayey soil after inclusion of carpet fibre waste

Abstract

To acquire deeper understanding and insights into the mechanical behaviour of fibre reinforced saturated/unsaturated cohesive soils, a programme of work was designed and included. 1) Conducting standard Consolidation Undrained (CU) tests to investigate mechanical behaviour of non-reinforced fully saturated soil. 2) Studying the strength of fibre reinforced clay though unconfined compression tests. 3) Testing the behaviour of unsaturated reinforced soil in unsaturated triaxial tests. 4) Determining the soil-water characteristic curves (SWCC) on soil sample with different fibre content. The investigation was undertaken on a clay of low plasticity index. Samples tested with addition of 1, 3 and 5 % fibre content and different values of matric suction of 50, 100 and 200 kPa, one of the challenges that were encountered in this research are how to prepare homogenous samples. A method for prepared compacted fibre reinforced soils with improved fibre distribution and density profile has been proposed and examined. The test results indicated that waste carpet fibres increase the shear strength of unsaturated clay soils. It was also found that relative increase in strength is also a function of applied suction. An increase in waste carpet fibres was found to reduce the hysteresis of soil. A data analysis conducted on the results of unsaturated tests as a function of fibre content and matric suction. The behaviour modelled was shown to be a perfect fit with the experimental data.