Optimization of lime and fiber content for improvement of clays with different plasticity using response surface method (RSM)

Abstract

Concurrent stabilization and fiber reinforcement is a common method for improving soft clay characteristics. Enhancements are function of percentage lime, fiber content and length and curing regime. Parallel assessment of these factors on mixture characteristics is arduous and interpretation of the results difficult. Thus, Response Surface Method (RSM) is adopted as a complementary method to reduce the number of tests required and interpretation of observations. In present study effects of plasticity index (10, 17 & 24%), lime content (1, 3 & 5%), percent fiber (0.1, 0.15 & 0.2%), fiber length (6, 12 & 18 mm) and curing period (1, 7 and 28 days) on features of composite mixtures has been explored using uniaxial compression tests. Results show concurrent lime stabilization and random fiber inclusion improves strength and strain characteristics with curing time. Varying clay plasticity resulted in improvement of uniaxial compressive strengths (UCS). RSM method and sensitivity analysis conducted showed lime content is the most and fiber content and length are the least influential factors on UCS and strain at failure. Scanning Electron Microscopy exposed that lime treatment and the formation of chemical compounds develop a coherent matrix binding clay particles and fibers at interfaces resulting in significant improvement in composite strength.