Geotechnical and micro-structural behaviour of chemically stabilized tropical residual soil

The stabilization of soils with additives is a chemically modified method that can be used to improve soils with weak engineering properties. Non-traditional additives such as ionic, enzymes, salts, polymers, and tree resins are widely used for treating problematic soils. The effects of non-traditio...

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Main Author:	Latifi, Nima
Format:	Thesis
Language:	English
Published:	2014
Subjects:	TA Engineering (General) Civil engineering (General)
Online Access:	http://eprints.utm.my/id/eprint/77778/1/NimaLatifiPFKA2014.pdf
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spelling	my-utm-ep.777782018-07-04T11:44:26Z Geotechnical and micro-structural behaviour of chemically stabilized tropical residual soil 2014-06 Latifi, Nima TA Engineering (General). Civil engineering (General) The stabilization of soils with additives is a chemically modified method that can be used to improve soils with weak engineering properties. Non-traditional additives such as ionic, enzymes, salts, polymers, and tree resins are widely used for treating problematic soils. The effects of non-traditional additives on the geotechnical properties of soils have been the issue of investigation in recent years. The publications on macro-structural, micro-structural, and molecular characteristics of tropical residual soil stabilized by non-traditional stabilizers are limited. This research aimed at determining the stabilization mechanism and performance of the tropical residual (laterite) soil mixed with two types of non-traditional stabilizer; namely the calcium based powder stabilizer (SH-85) and sodium silicate based liquid stabilizer (TX-85). Macro-structural study including the compaction, unconfined compression strength, direct shear, and consolidation tests were used to assess the engineering properties of the stabilized soil. The physico-chemical bonding mechanisms contributed to the stabilization process were discussed based on the results of micro-structural study from different spectroscopic and microscopic techniques such as X-ray Diffractometry, Energy-Dispersive X-ray Spectrometry, Field Emission Scanning Electron Microscopy, Fourier Transform Infrared Spectroscopy, Surface Area Analysis and Thermal Gravimetric Analysis. In addition, the performance of treated laterite backfill stabilized with the selected additives was evaluated using series of physical model tests. The model tests consisted of strip footing placed on stabilized backfill behind sheet pile wall. The numerical simulation using PLAXIS finite element (FE) software was carried out to compare and evaluate the results obtained from the physical models. The laboratory tests showed that the addition of 9 % (as the optimum amount) of both additives increased more than 80% of compressive strength after 7 days of curing periods while the consolidation settlement had been effectively reduced. The micro-structural study revealed that the stabilization process modified the porous network of laterite soil. The pores of the soil had been filled by the newly formed compounds known as calcium aluminate hydrate cementitious material for SH-85 treated samples and sodium aluminosilicate hydrate gel-like product for TX-85 treated samples. Hence, the stabilization mechanism of two selected non-traditional additives was by cationic exchange and physical bonding. The numerical simulation and physical modelling showed identical trends. Therefore the finite element method using elasto-plastic Mohr-Coulomb model is suitable to be used in evaluating and predicting the behaviour of chemically stabilized backfill. The results from the physical model tests showed that the ultimate capacity of the footing placed on the stabilized backfill soil increased greatly while the settlement reduced compared to untreated backfill laterite soil, after just 7 days of curing. It can be concluded that the quick reaction of the selected stabilizers with laterite soils is very advantageous and cost-effective for geotechnical engineering projects. 2014-06 Thesis http://eprints.utm.my/id/eprint/77778/ http://eprints.utm.my/id/eprint/77778/1/NimaLatifiPFKA2014.pdf application/pdf en public http://dms.library.utm.my:8080/vital/access/manager/Repository/vital:98391 phd doctoral Universiti Teknologi Malaysia, Faculty of Civil Engineering Faculty of Civil Engineering
institution	Universiti Teknologi Malaysia
collection	UTM Institutional Repository
language	English
topic	TA Engineering (General) Civil engineering (General)
spellingShingle	TA Engineering (General) Civil engineering (General) Latifi, Nima Geotechnical and micro-structural behaviour of chemically stabilized tropical residual soil
description	The stabilization of soils with additives is a chemically modified method that can be used to improve soils with weak engineering properties. Non-traditional additives such as ionic, enzymes, salts, polymers, and tree resins are widely used for treating problematic soils. The effects of non-traditional additives on the geotechnical properties of soils have been the issue of investigation in recent years. The publications on macro-structural, micro-structural, and molecular characteristics of tropical residual soil stabilized by non-traditional stabilizers are limited. This research aimed at determining the stabilization mechanism and performance of the tropical residual (laterite) soil mixed with two types of non-traditional stabilizer; namely the calcium based powder stabilizer (SH-85) and sodium silicate based liquid stabilizer (TX-85). Macro-structural study including the compaction, unconfined compression strength, direct shear, and consolidation tests were used to assess the engineering properties of the stabilized soil. The physico-chemical bonding mechanisms contributed to the stabilization process were discussed based on the results of micro-structural study from different spectroscopic and microscopic techniques such as X-ray Diffractometry, Energy-Dispersive X-ray Spectrometry, Field Emission Scanning Electron Microscopy, Fourier Transform Infrared Spectroscopy, Surface Area Analysis and Thermal Gravimetric Analysis. In addition, the performance of treated laterite backfill stabilized with the selected additives was evaluated using series of physical model tests. The model tests consisted of strip footing placed on stabilized backfill behind sheet pile wall. The numerical simulation using PLAXIS finite element (FE) software was carried out to compare and evaluate the results obtained from the physical models. The laboratory tests showed that the addition of 9 % (as the optimum amount) of both additives increased more than 80% of compressive strength after 7 days of curing periods while the consolidation settlement had been effectively reduced. The micro-structural study revealed that the stabilization process modified the porous network of laterite soil. The pores of the soil had been filled by the newly formed compounds known as calcium aluminate hydrate cementitious material for SH-85 treated samples and sodium aluminosilicate hydrate gel-like product for TX-85 treated samples. Hence, the stabilization mechanism of two selected non-traditional additives was by cationic exchange and physical bonding. The numerical simulation and physical modelling showed identical trends. Therefore the finite element method using elasto-plastic Mohr-Coulomb model is suitable to be used in evaluating and predicting the behaviour of chemically stabilized backfill. The results from the physical model tests showed that the ultimate capacity of the footing placed on the stabilized backfill soil increased greatly while the settlement reduced compared to untreated backfill laterite soil, after just 7 days of curing. It can be concluded that the quick reaction of the selected stabilizers with laterite soils is very advantageous and cost-effective for geotechnical engineering projects.
format	Thesis
qualification_name	Doctor of Philosophy (PhD.)
qualification_level	Doctorate
author	Latifi, Nima
author_facet	Latifi, Nima
author_sort	Latifi, Nima
title	Geotechnical and micro-structural behaviour of chemically stabilized tropical residual soil
title_short	Geotechnical and micro-structural behaviour of chemically stabilized tropical residual soil
title_full	Geotechnical and micro-structural behaviour of chemically stabilized tropical residual soil
title_fullStr	Geotechnical and micro-structural behaviour of chemically stabilized tropical residual soil
title_full_unstemmed	Geotechnical and micro-structural behaviour of chemically stabilized tropical residual soil
title_sort	geotechnical and micro-structural behaviour of chemically stabilized tropical residual soil
granting_institution	Universiti Teknologi Malaysia, Faculty of Civil Engineering
granting_department	Faculty of Civil Engineering
publishDate	2014
url	http://eprints.utm.my/id/eprint/77778/1/NimaLatifiPFKA2014.pdf
_version_	1747817828667359232

Geotechnical and micro-structural behaviour of chemically stabilized tropical residual soil

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