Effect of Curing on Micro-Physical Performance of Polypropylene Fiber Reinforced and Silica Fume stabilized Expansive Soil Under Freezing Thawing Cycles

Nitin Tiwari,Kundan Singh,Neelima Satyam

doi:10.1038/s41598-020-64658-1

Abstract

This study presents the micro-physical investigation of polypropylene (PP) fiber-reinforced, and silica fume (SF) stabilized expansive soil (BC) subgrade. The coupling effect of soil, PP fiber, and SF has been evaluated under the freezing-thawing (F-T) cycle to assess the durability of treated BC Soil. The curing method and duration staggeringly influence the strength of SF treated BC soil; therefore, three different curing method, i.e., moisture-controlled curing (MC), gunny bag curing (GC), and water submerged curing (SC) to a period of 7, 14, and 28 days were considered. The BC soil has been reinforced with 0.25%, 0.50%, and 1.00% PP fiber and stabilized with 2%, 4%, 6% and 8% SF. The physical, chemical, and microstructural properties were determined before and after 2,4,6,8,10 F-T cycles. With the increase in SF content, the unconfined compressive strength of the expansive soil has been increased due to the formation of Calcium Silicate Hydrate (C-S-H) gel. The chemically inert, hydrophobic, non-corrosive nature, and higher tensile strength of PP fiber, it has a higher potential to reinforce the BC soil for durability under tensile failure. This research confirms the possibility of incorporating SF and PP Fiber in road work applications, with significant environmental benefits.

Highlights

The layered structure of the clay minerals and cations adsorbed for the charged equilibrium induced swelling-shrinkage in expansive soil[6]
The effect of the curing method on the unconfined compressive strength of the PP fiber-reinforced and silica fume (SF) stabilized expansive soil is shown in Fig. 8 under the freezing-thawing cycle
The effect of the curing method on the ultrasonic pulse velocity test (UPV) of the PP fiber-reinforced and SF stabilized expansive soil is shown in Fig. 9 under the freezing-thawing cycle

Summary

Introduction

The layered structure of the clay minerals and cations adsorbed for the charged equilibrium induced swelling-shrinkage in expansive soil[6]. The chemical stabilization is a substantiate quick-fix method to improve the shear strength and reduces the swelling shrinkage nature of expansive soil[24,25,26,27]. Cement has used as a conventional chemical stabilizer to improve the engineering properties of soil, such as strength and durability[35]; it causes global warming due to CO2 emission[36,37]. A silica fume is one of the non-expansive industrial waste materials that significantly improves the strength and reduces upward swell pressure in expansive soil subgrades[26]. Yixian et al 2019, presented improvement in the mechanical behavior of wheat straw fiber reinforcement and lime stabilization clayey soil at the microstructural level[64]. The chemical changes were evaluated using calcite content (CCt), pH, and electrical conductivity (EC)

Objectives

Methods

Results

Conclusion