Effects of Glass-Fiber Reinforced Polymer and Waste Polypropylene Plastic Particles on Geotechnical Properties of Clayey Soils for Using Subgrade in the Pavement

Document Type: Research Paper


1 M.Sc., Department of Civil Engineering,, East Azerbaijan Science and Research Branch, Islamic Azad University, Tabriz Branch, Tabriz, Iran

2 M.Sc. Department of Civil Engineering, East Azerbaijan Science and Research Branch, Islamic Azad University, Tabriz Branch, Tabriz, Iran

3 Assistant Professor, Department of Civil Engineering, Tabriz Branch, Islamic Azad University, Tabriz, Iran

4 Assistant Professor, California State Polytechnic University Pomona, USA



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.


-Andersland, O. B. and Khattak, A. S. (1997) “Shear strength of kaolinite/fiber soil mixtures”, Proc. International Conference on Soil Reinforcement, Paris, France.

- Arenzic, R. M. and Chowdhury, R. N. (1988) “Laboratory investigation of earth walls simultaneously reinforced by strips and random Reinforcement,” Geotechnical Testing Journal, ASTM, Vol. 11, No. 4, pp.241-247.

- Asadollahi, F. and Dabiri, R. (2017) “Effects of glass fiber reinforced polymer on geotechnical properties of clayey soil”, Journal of Structural Engineering and Geotechnics, Vol.7, No.2, pp.73-83.

-ASTM D421-85 (1985) “Dry Preparation of Soil Samples for Particle-Size Analysis and Determination of Soil Constants, Annual book of ASTM standards, (reapproved 1998).

-ASTM D1883-93 (1993) “Standard test method for CBR (California bearing ratio) of laboratory- compacted soils”, Annual book of ASTM standards.

-ASTM D 4318-95a (1995) “Standard test method for liquid limit, plastic limit and plasticity index for soils”, Annual book of ASTM standards.

-ASTM-D 4972 (1995) “Standard test method for PH of soils”, Annual book of ASTM standards.

-ASTM D422-98, (1998) “Standard Test Method for article-Size Analysis of Soils”, Annual book of ASTM standards (reapproved 1998).

-ASTM-D 3080-98 (1998) “Standard test method for direct shear test of soils under consolidated drained condition”, Annual book of ASTM standards.

-ASTM-D 698-00 (2000) “Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Standard Effort (12,400 ft-lbf/ft3 (600 kN-m/m3))”, Annual book of ASTM standards.

-ASTM-D 854-02, (2002) “Standard test method for specific gravity of soil solids by water pycnometer”, Annual book of ASTM standards.

-ASTM-D 5084-04, (2004) “Standard test method for measurement of hydraulic conductivity of saturated porous materials using flexible wall permeameter”, Annual book of ASTM standards.

-ASTM-D 2166/D2166M-13, (2013) “Standard test method for unconfined compressive strength of cohesive soils”, Annual Book of ASTM standards.

-Ayan, V., Khavandi, A., Omer, J. R. and Limbachiya, M. C. (2016) “Toughness performance of recycled aggregates for use in road pavement”, International Journal of Transportation Engineering, Vol.3, No.3, pp.171-179.

-Benson, C. H. and Khire, M. V. (1994) “Reinforcing sand with strips of reclaimed high-density polyethylene,” Journal of Geotechnical and Geoenvironmental Engineering, ASCE, Vol. 120, No. 5, pp.828-855.

-Cai, Y., Shi, B., NG, C. W. W. and Tang, C. (2006) “Effect of polypropylene fiber and lime admixture on engineering properties of clayed soil”, Engineering Geology, Vol.87, pp.230-240.

-Cristelo, N., Cunha, M. C., Dias, M., Gomes, T. A., Miranda, T. and Araujo, N., (2015) “Influence of discrete fiber reinforcement on the uniaxial compression response and seismic wave velocity of a cement-stabilized sandy-clay”, Geotextiles and Geomembranes, Vol.43, pp.1-13.

-Dean, R. and Freitag, F. (1986) “Soil randomly reinforced with fibers”, Journal of Geotechnical and Geoenvironmental Engineering, ASCE, Vol. 112, No. 4, pp. 823-827.

-Erdinciler, A., Ayhan, V. (2010) “Influence of tire fiber inclusions on shear strength sand”, Geosynthetic International journal, Vol.17, pp.183-192.

-Ghasemvash, S. and Dabiri, R. (2019) “Effects of geotextile applications on bearing capacity clay-gravel mixtures in pavement Layers”, Journal of Engineering Geology, Vol.13, No.3, (In Press, In Persian).

-Khabiri, M. M. (2011) “Geosynthetic material suitable depth staying to control failure of pavement rutting”, Advanced Materials Research, Vols. 255-260, pp. 3454-3458.

-Kumar Senthil, P. and Rajkumar, R (2012) “Effect of Geotextile on CBR Strength of Unpaved Road with Soft Subgrade”, Electronic Journal of Geotechnical Engineering, (EJGE), Vol.17, Bundle J, pp.1355- 1363.


-Michalowski, R. and Zoba, A. (1996) “Failure of fiber reinforced granular Soils”, Journal of Geotechnical and Geoenvironmental Engineering, ASCE, Vol. 122, No. 3, pp. 226-234.

-Nazari, R. and Dabiri, R (2016) “Comparison of geotextile layers effects on static and dynamic behavior of pavement”, Journal of Structural Engineering and Geotechniques, Vol.6, No.2, pp. 15-22.

-Ranjan, G., Vasan, R. M. and Charan, H.D. (1996) “Probabilistic analysis of Randomly Distributed Fiber Reinforced Soil,” Journal of Geotechnical and Geoenvironmental Engineering, ASCE, Vol. 122, No. 6, pp. 419 – 426.

-Rustin Resin Company, GFRP manufacturing, www.rustinco.ir.

-Sadeghi Azar, K. and Dabiri, R (2015) “The Effects of Geotextile Layers on Bearing Capacity of Gravel-Silt Mixture”, Trakya University Journal of Engineering Science, Vol.16, No.2, pp.61-69.

-Sahebkaram Alamdari, A. and Dabiri, R. (2017) “Effects of the fibers type on improving the bearing capacity of clayey soil”, International Journal on Technical and Physical Problems of Engineering, Vol.9, No.1, pp.43-50.

-Sukantasokl, P., Jamsawang, P., (2012) “Use of steel and polypropylene fibers to improve flexural performance of deep soil-cement column”, Construction Building Material, Vol.29, No.1, pp.201-215.

-Wang, Y., Frost, J. D. and Murray, J. (2000) “Utilization of recycled fiber for soil stabilization”, Proceedings of the Fiber Society Meeting, May 17-19, Guimaraes, Portugal, pp.59-62.