Undrained performance of sustainable compacted sand-bentonite–glass fiber composite for landfill application

Abstract

Abstract A compacted sand-bentonite composite is considered as a barrier material for the use at the landfill. If the strength of the barrier material is not adequate, then the actual operation of the liner system can be endangered. Worldwide environmental awareness and high dumping cost have influenced the possible use of glass fibers for landfill application. Since the composite possessed a lower shear strength, glass fiber can be added to enhance its shear strength. The purpose of the present investigation was to assess the effective shear strength parameters of compacted sand–bentonite mixture, mixed in a proportion of 80:20 and reinforced with glass fiber. Glass fiber with an aspect ratio of 40, 80, and 120 were added to sand-bentonite composite in a fraction of 0.5, 1, and 1.5%. Test result suggested that the negative excess pore water pressure increased for the composite with an aspect ratio of 40; however, it decreased gradually with an increase in the aspect ratio to 80 and 120 for any fiber concentration. At a fiber content of 1.5% with the aspect ratio of 80 and 120, the peak effective frictional angle was almost constant. The cohesion component enhanced moderately up to the aspect ratio of 80 for any fiber concentration and remained constant with a further increase in the aspect ratio from 80 to 120. Residual strength parameter of the composite improved significantly with the addition of glass fiber. Initial tangent increased up to 1% fiber content for any aspect ratio, and then reduced with the further addition of glass fiber. The effective principal stress at failure predicted using a mathematical model showed an excellent agreement between predicted and experimental values.