Stabilization of a Residual Soil Using Calcium and Magnesium Hydroxide Nanoparticles: A Quick Precipitation Method

Lee Li Yong,Endene Emmanuel,Agusril Syamsir,Suvash Chandra Paul,Vivi Anggraini,S.V.A.D Namal Jayasanka Perera

doi:10.3390/app9204325

Abstract

The current study examines the potential of using calcium and magnesium hydroxide nanoparticles synthetized through a quick precipitation method as soil stabilizers for improving the engineering properties of tropical residual soil. The engineering properties of untreated and nanoparticles-treated soil were studied by carrying out a series of geotechnical tests including compaction, Atterberg limits, falling head permeability, and unconfined compressive strength (UCS). The stabilization mechanisms associated with soil–chemical reactions were further explored by performing microstructural analyses such as x-ray diffraction (XRD), variable-pressure scanning electron microscope (VP-SEM), and energy-dispersive x-ray spectroscopy (EDX). The findings revealed that the calcium hydroxide and magnesium hydroxide nanoparticles improved the geotechnical properties of residual soils in terms of reduced hydraulic conductivity and increased UCS. The percentage reduction of the hydraulic conductivity of magnesium and calcium hydroxide nanoparticles-treated soils compared to untreated soil after seven weeks of permeation were 85.14% and 98.70%, respectively. The magnesium and calcium hydroxide nanoparticles-treated soils subjected to 14 days of curing recorded a percentage increase in the UCS of 148.05% and 180.17%, respectively compared to untreated soil. Hence, it can be concluded that both magnesium and calcium hydroxide nanoparticles can be effectively utilized as environmental-friendly stabilizers.

Highlights

Residual soils are the products of in situ rock weathering induced by the interaction of natural feature such as environmental conditions and chemical compositions of the parent rock over an extended period
Results showed that the liquid limit and plastic limit of residual soils treated with two different nanoparticles decreased; the plasticity index, which is the difference between the liquid limit and plastic limit, decreased
The changes in the Atterberg limits with the addition of nanoparticles can be related to the diffuse double layer (DDL) theory

Summary

Introduction

Residual soils are the products of in situ rock weathering induced by the interaction of natural feature such as environmental conditions and chemical compositions of the parent rock over an extended period. The high temperatures and heavy rainfalls in tropical regions contribute significantly to the intense rock weathering process and favor the formation of tropical residual soils [1]. The predominance of chemical weathering in tropical regions which occurs gradually over time results in the formation of iron oxides/hydroxides and fine-grained clay. Sci. 2019, 9, 4325 minerals [3]. The significant percentage of silt and clay present in the tropical residual soil deposits may cause the soils to experience poor engineering properties [4,5]. Soil stabilization is required to improve the engineering properties of such tropical residual soils prior to their application in various construction works

Objectives

Results

Conclusion