The study of fracture mechanics of PET fiber-reinforced soils based on flexural tests and imaging techniques

Abstract

An emerging alternative to improve the mechanical properties of fine soils susceptible to cracking is the addition of fibers obtained from reused synthetic materials such as polyethylene terephthalate (PET). The technical literature on the fracture mechanics of PET fiber-reinforced soils is rather scarce, so there has been insufficient progress in determining fracture parameters and standardized procedures to find optimal reinforcement conditions. This research uses experimental techniques to induce tensile stresses in clayey silty soil samples from the Valley of Mexico reinforced with different fiber contents. By applying approaches based on linear elastic and elastoplastic theory, parameters useful for the study of fracture mechanics and flexural strength of PET-reinforced soil were estimated: tensile strength, critical energy release rate, critical stress intensity factor, and contour integral for crack propagation under plasticity. In addition, imaging techniques are used to measure the deformations generated in bending tests of reinforced soil beams and to study crack propagation from initiation to maximum stresses. The addition of PET fibers significantly improved soil response by reducing cracking, increasing tensile strength, and providing ductile behavior as cracking progressed. These effects indicate the great potential of recycled PET fibers as a subgrade improvement method for soft, cracking soil deposits, or even for earthworks and slope stabilization in clayey soils on road projects.