Document Type: Research Paper
Department of Civil Engineering, East Azerbaijan Science and Research Branch, Islamic Azad Univbersity, Tabriz, Iran
Department of Civil Engineering, East Azerbaijan Science and Research Branch, Islamic Azad University, Tabriz, Iran
Department of Civil Engineering, Tabriz Branch, Islamic Azad University, Tabriz, Iran
California State Polytechnic University Pomona, 3801 W. Temple Ave. Pomona, CA 91768
The fine-grained soil including the problematic ones can cause many difficulties in project accomplishment. Settlement and swelling are among the problems of the fine-grained soils. The present study compared the effects of the polypropylene waste plastic (PWP) and glass fiber reinforced polymer (GFRP) on geotechnical properties of the clayey soils for the subgrade design. To this end, the PWP and GFRP were randomly mixed with the fine soils of different plasticity indexes in similar weight percentages (i.e., 0.25, 0.50, 0.75, and 1). Further, compaction, unconfined compressive, direct shear, and California bearing ratio tests were performed in both dry and saturated conditions, followed by conducting the falling head permeability test. The results showed that PWP and GFRP materials were effective in the swelling potential of the clayey soil. In other words, the swelling potential decreased by about 32% and 33% in both CH and CL samples when the PWP content increased up to 0.75% in the specimens, respectively. In addition, this potential decreased by 60% when the GFRP (0.75%) was added to the specimens. Also, bearing capacity and elastic modulus increased mixing PWP (0.75%) or GFRP (0.5%) in the clayey soils by high and low plasticity indexes. Therefore, the improved soils can be used to make a subgrade layer for the pavement.