Experimental Study on the Mechanical Behavior of Cemented Soil Reinforced with Straw Fiber

Abstract

An experimental program was conducted to evaluate the effect of straw fibers and cement percents on the mechanical properties of low plasticity clay soil. This research work aimed to assess if the straw fibers addition can enhance the strength properties of untreated and cement treated soil. Further, a few numbers of researches have been done on using straw fibers in reinforcing clay soils. In the present study, four percent; based on the dry weight of soil; of straw fibers (0.25, 0.5, 1.0 and 1.5%) and three percent of cement (2, 4 and 6%) were used. All soil samples (untreated and cement treated samples) were prepared at optimum moisture content (OMC) and maximum dry unit weight (γdmax) of natural soil. The cemented un-reinforced and fiber-reinforced samples were cured for different curing periods (varied between 3 to 90 days) at 20 °C. Different tests including unconfined compression, P-wave velocity, water absorption capacity (WAC) of straw fiber, electrical conductivity, pH and scanning electron microscopy tests were investigated. The test results show that the strength behavior of soil samples depends considerably on the percents of both straw fibers and cement. The increase in the unconfined compressive strength (UCS) is most apparent in the un-cemented and cemented soil samples having 0.5% straw fibers percent. While this increase in the UCS is linear with increasing cement percent (i.e. as cement percent increase the UCS increased). Further, the contribution of both straw fibers and cement percents in the increasing the UCS is much more than the increase caused by them individually. The stress–strain behavior of soil samples changes from brittle behavior to ductile one with straw fiber addition.