PET fiber reinforcement efficiency in the mechanical and microstructural characteristics of cemented sand modified with silica fume

Abstract

One of the techniques employed in geotechnical engineering to deal with poor soils is to modify their mechanical properties using cement. On the other hand, a number of recent studies considered environmental protection by employing waste and low-cost materials for engineering applications. Hence, in this investigation, a total of 102 consolidated undrained (CU) triaxial tests have been carried out to explore the combined effects of two kinds of these materials, i.e., silica fume particles and polyethylene terephthalate (PET) fibers on the mechanical behavior of cemented sand. The cement contents were 0, 3, 5 and 7% (by weight of the dry sand), silica fume contents were 0 and 0.5% (by weight of the dry sand) and PET fiber contents were 0, 0.65, 0.75 and 0.85% (by weight of the dry sand) with lengths of 8, 10 and 12 mm. Various properties including stress–strain curves, deformation characteristics and failure mechanism, pore water pressure-strain curves, peak deviatoric stress, stiffness, brittleness index, energy absorption capacity (EAC) and shear strength parameters were interpreted and discussed. The results revealed that the inclusion of PET fibers to silica fume-cemented sand affects the shear strength parameters, EAC, stiffness and brittleness index significantly. For example, by adding 0.65% PET fibers with length of 10 mm to sand with 5% cement and 0.5% silica fume, the EAC value increases from 224 to 344 MJ/m3 (53% growth). However, with the increase of PET content more than 0.75%, the improvement in the mechanical performance of samples is not remarkable. Finally, the results of Scanning Electron Microscopy (SEM) tests confirmed the results of triaxial tests.