Effect of polypropylene fiber and nano-zeolite on stabilized soft soil under wet-dry cycles

Abstract

Nano-zeolite was used in the present study as a substitute for a part of lime and then inclusion polypropylene fiber in stabilized soil matrix to develop the soil stabilization method with lime and to improve the efficiency of this technique. In so doing, specimens of soft soil with 5, 10 and 15% of modifier L (lime), LZ (lime-nano-zeolite) and LZF (lime-nano-zeolite-fiber) were prepared, and were subjected to 1–7 wet-dry cycles. Then, microstructure and macrostructure tests were performed on the specimens. The results of the analyses, indicated that the optimal replacement of lime with nano-zeolite would be 40%, and the optimal amount of polypropylene fibers inclusion would be 1% in the stabilized soil matrix. Major reduction in lime consumption would yield a 40% increase in compressive strength and a 21% improvement in durability. The results also showed that the specimen containing 15%LZF would have excellent durability against environmental conditions and very good performance in terms of unconfined compressive strength (UCS), tensile strength and weight loss. Before and after applying 7 wet-dry cycles, the UCS increased by 39% and 16%, respectively. The results of this study indicate that LZF modifier is a suitable option for lime-based stabilization in areas under wet-dry cycles.