Response of Natural Rubber Latex Treated Soils Under Static and Cyclic Loading

Abstract

The present study attempts the application of Natural Rubber Latex (NRL) to improve di erent mechanical characteristics of the soil. The study mainly focuses on the strength and ductility characteristics, liquefaction resistance and volume change behaviour of NRL-treated soils. Three types of locally available soils, such as low plastic soil (LPS), medium plastic soil (MPS) and high plastic soil (HPS), were used for the evaluation of load-deformation behaviour by conducting uncon ned compression (UCS) tests. NRL was added to dry soil in di erent proportions, maintaining the water content below the optimum moisture content for that soil. Even if the treatment enhanced the strength compared to the conventional techniques, the improvement is not appreciable. The ductile nature of the soil was quanti ed in terms of three parameters such as deformability index, energy absorption index and brittleness index. With an increase in NRL content, treated soil's deformability index and energy absorption index both markedly improved, while its brittleness index decreased. The test results show that NRL treatment help to enhance the ductility of soil without compromising the strength. The commercially available Quartzanium grade III sand was used for the cyclic response and liquefaction studies. The strain-controlled cyclic triaxial tests with a frequency of 1 Hz and shear strain amplitudes of 0.225%, 0.45% and 0.75% were performed for assessing the liquefaction resistance and modulus degradation. The NRL-treated samples were prepared using a pressurised permeation method to permeate ready-prepared sand samples with NRL solutions of concentrations ranging from 10 to 30%. The study considered a unit value of pore pressure ratio to indicate onset of liquefaction. The outcomes of strain-controlled cyclic triaxial tests showed that the NRL treatment e ectively lowers the pore pressure build-up and prevents liquefaction. The performance of the treated sand improved with an increase in the concentration of NRL solution used for the treatment. To comprehend the development of excessive cyclic strain, which is an essential feature of liquefaction, a set of stress-controlled tests with a CSR value of 0.2 were also performed. The ndings showed that the treated sand did not experience excessive strain despite the development of pore pressure because the coagulated rubber bindings prevented the excessive displacement of sand particles. Hence NRL treatment can be proposed as an e cient ground improvement technique for liquefaction remediation. To understand the impact of NRL treatment on the volume change behaviour of soil, one-dimensional swelling and consolidation tests were performed on untreated and treated samples of LPS, MPS and HPS. The NRL treatment lowered the swelling potential and swelling pressure of HPS, which is of expansive nature in its virgin state, though it raised the swelling potential of LPS and MPS marginally. In all three soils, NRL helped to reduce the compression index, Cc, while the resilient nature of NRL increased the recompression index, Cr, of all soils. The reduction in compressibility was maximum in HPS with a minimum increase in the recompression index. The results indicate that NRL treatment is an e ective technique for reducing volume change-related problems in highly compressible soils