Effect of Waste Human Hair Fibers on Shear Behavior of Sand in Dry and Saturated Conditions

Abstract

Abstract Soil reinforcement using natural fibers has been successfully employed in different projects. Among the natural fibers, the use of waste human hair fibers as a reinforcing material can be the solution for sustainable development. This study presents characterization of human hair fiber–reinforced sand using direct shear tests under dry and saturated conditions. Tests were conducted in three series: (i) Test Series-1: using unsorted human hair fibers (as collected from barber shops) under dry conditions, (ii) Test Series-2: using unsorted human hair fibers under saturated conditions, and (iii) Test Series-3: sorted fibers with lengths of 10, 15, and 20 mm to examine the effect of fiber length when under saturated conditions of sand. All test specimens were prepared at 80 % relative density. Initially, experiments were carried out on dry sand with fiber reinforcement up to 2.0 % by weight of sand. Under saturated conditions, the percentage of fiber content was restricted up to 1.0 %, as formation of fiber clusters was noticed beyond 1.0 %. Under saturated conditions, specimens were prepared with initial moisture content ranging from 1.0–3.0 % by weight of soil for easy homogeneous mixing and then saturated. It is found that the reinforcement using human hair fibers significantly affects the shear behavior of dry sand. However, under saturated conditions, the human hair fiber reinforcement is able to sustain shear strength parameters similar to unreinforced sand, even though these parameters are likely to reduce. The use of unsorted fibers as reinforcement is more beneficial than that the use of the sorted fibers of uniform length.