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Affected by the developed pore water pressure during undrained cyclic shear of saturated soils, granular soil liquefaction is regarded as a common phenomenon that occurs under earthquake loads. This phenomenon causes huge damage to infrastructure. Different reinforcement materials have been successfully implemented with particular attention to the use of waste materials to satisfy design specifications and mitigate the adverse environmental effects. This paper aims to investigate the possibility of using waste plastic fibers as reinforcement materials to mitigate liquefaction potential and pore pressure generation of reinforced sand under cyclic loading. For this purpose, 42 stress-controlled cyclic triaxial tests were conducted on Babolsar sand, reinforced by Poly-Ethylene Terephthalate (PET) and Polypropylene (PP) fibers with the fiber contents of 0.25%, 0.5%, and 1% under the confining pressures of 50, 100, and 200 kPa at Cyclic Stress Ratios (CSR) of 0.2 and 0.35. The obtained results revealed that the addition of these waste plastic fibers could significantly increase the liquefaction resistance of Babolsar sand and that with an increase in the waste content, the number of cycles leading to liquefaction would increase. Addition of wastes decreased the pore water pressure generation, and this effect was more pronounced with an increase in the waste content. [ABSTRACT FROM AUTHOR]

A series of triaxial compression tests were performed to evaluate the benefits of plastic wastes and investigate the engineering properties of sand reinforced with these materials. In this research, the effects of plastic waste contents (0, 0.25, 0.5, 0.75, and 1% by dry weight of sand), types of plastic wastes -polyethylene terephthalate (PET) and polypropylene (PP) fibers- and confining pressures (50, 100 and 200 kPa) on the behavior of Babolsar sand were investigated. The values of deformation modulus (up to 84%), peak (up to 7 times of the unreinforced sand) and steady state shear strength increased with reinforcement. Also, axial strain at failure for fiber-reinforced sand increased up to 1.5 times of unreinforced one (from 3.36% to 8.53% for 1% PP usage at 50 kPa confining pressure). Therefore, it can be generally stated that the use of plastic wastes in the sand leads to low cost soil reinforcement and also lessens the disposal problem of these kinds of wastes. [ABSTRACT FROM AUTHOR]

This paper presents the swelling and consolidation characteristics of lignosulfonate (LS) stabilized expansive clay. Expansive clay samples of Amol city in Iran have been used in this research. Based on Atterberg limits and unconfined compressive strength tests, the optimum percentage of LS for the treatment of this clay was determined at 0.75% by soil dry weight. To investigate the swelling and consolidation properties of untreated and LS-treated remolded samples, one-dimensional swell and consolidation tests were conducted on these samples. Test results showed that LS had considerable effect on the consolidation and swelling behavior of the expansive clay. Moreover, the effects of compaction water content change and cyclic wetting and drying on the volume change properties of unstabilized and LS-stabilized samples were investigated. Untreated and LS-treated specimens showed different consolidation behaviors towards the variations of compaction moisture content due to the alteration of soil expansivity category from high to moderate. The Scanning Electron Microscope (SEM) images of samples showed that the soil specific area was reduced because of stabilization. This reduction in soil specific area led to the decrease of affinity of samples to moisture increase; thus, the volume change of expansive clay decreased. [ABSTRACT FROM AUTHOR]