Improvement of a tropical residual soil by electrokinetic process

Tropical residual soils are generally heterogeneous and partially saturated. These soils attain their strength from capillary stresses as well as cementation of soil particles by clay minerals and sesquioxides. The strength however reduces significantly upon saturation due to the collapse of capilla...

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Main Author:	Ahmad, Kamarudin
Format:	Thesis
Language:	English
Published:	2004
Subjects:	TP Chemical technology
Online Access:	http://eprints.utm.my/id/eprint/4611/1/KamarudinAhmadPFKA2004.pdf
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spelling	my-utm-ep.46112018-02-28T06:45:57Z Improvement of a tropical residual soil by electrokinetic process 2004-05 Ahmad, Kamarudin TP Chemical technology TA Engineering (General). Civil engineering (General) Tropical residual soils are generally heterogeneous and partially saturated. These soils attain their strength from capillary stresses as well as cementation of soil particles by clay minerals and sesquioxides. The strength however reduces significantly upon saturation due to the collapse of capillary stresses and increase in pore water pressures. Such strength reductions may lead to soil instability. The effectiveness of additives to increase shear strength however is limited to small soil volume due to slow and restricted ion migration. Thus, electrokinetic (EK) processing was combined with chemical addition to increase ions diffusion. Experiments to study the feasibility of the combined methods to increase the shear strength of a compacted and saturated (C&S) tropical residual soil were performed using EK cells. The diameter and length of each EK cell were 10.0 cm and 5.0 cm, respectively. Open-anode and open-cathode systems were employed to treat soil samples densified to 90% of maximum dry density at the optimum moisture content. Injections of 1.0 M of calcium chloride, aluminium chloride and phosphoric acid were carried out via applications of 30 V DC electrical potential for 168 hours. Effects of EK treatments on compressibility and hydraulic conductivity were also investigated. The employment of distilled water (DW) as anolyte and phosphoric acid (PA) as catholyte resulted in the highest strength and lowest compressibility. The utilisation of the other chemicals as anolytes and DW as catholytes resulted either in strength reduction and higher compressibility or no significant changes in both the engineering properties both near the anodes and the cathodes. EK treatments also affected the values of hydraulic conductivity of the treated soils, depending on the utilised chemicals. On different molarity of PA as catholytes and DW as anolyte, ' the utilisation of 0.5 M PA resulted in the highest cohesion and lowest compressibility of the EK treated soil near the cathode. No significant changes were observed in the compressibility of the treated soils near the anodes from the utilisation of different PA concentrations. Regarding the EK parameters, the directions and quantities of net electroosmotic flows varied depending upon the chemicals used as the anolytes and catholytes. These chemicals influenced the pH of the soil-pore fluid chemistry, which determined the signs and values of zeta potential (<) during EK processing. No net flows were also observed because of isoelectric point (IEP) where < = 0 were achieved. The values of electroosmotic hydraulic conductivity (k,) varied with time and generally lower than the k, values of temperate soils reported in literatures. On different concentrations of PA as catholytes, 0.5 M PA was considered as the optimum concentration in this study because the utilisation of it produced the highest in strength, current density and net electroosmotic flow besides the lowest compressibility. X-ray fluorescence (XRF) analyses on the EK treated samples showed that the distributions of the EK-injected ions after treatments were not uniform. 2004-05 Thesis http://eprints.utm.my/id/eprint/4611/ http://eprints.utm.my/id/eprint/4611/1/KamarudinAhmadPFKA2004.pdf application/pdf en public phd doctoral Universiti Teknologi Malaysia, Faculty of Civil Engineering Faculty of Civil Engineering
institution	Universiti Teknologi Malaysia
collection	UTM Institutional Repository
language	English
topic	TP Chemical technology TP Chemical technology
spellingShingle	TP Chemical technology TP Chemical technology Ahmad, Kamarudin Improvement of a tropical residual soil by electrokinetic process
description	Tropical residual soils are generally heterogeneous and partially saturated. These soils attain their strength from capillary stresses as well as cementation of soil particles by clay minerals and sesquioxides. The strength however reduces significantly upon saturation due to the collapse of capillary stresses and increase in pore water pressures. Such strength reductions may lead to soil instability. The effectiveness of additives to increase shear strength however is limited to small soil volume due to slow and restricted ion migration. Thus, electrokinetic (EK) processing was combined with chemical addition to increase ions diffusion. Experiments to study the feasibility of the combined methods to increase the shear strength of a compacted and saturated (C&S) tropical residual soil were performed using EK cells. The diameter and length of each EK cell were 10.0 cm and 5.0 cm, respectively. Open-anode and open-cathode systems were employed to treat soil samples densified to 90% of maximum dry density at the optimum moisture content. Injections of 1.0 M of calcium chloride, aluminium chloride and phosphoric acid were carried out via applications of 30 V DC electrical potential for 168 hours. Effects of EK treatments on compressibility and hydraulic conductivity were also investigated. The employment of distilled water (DW) as anolyte and phosphoric acid (PA) as catholyte resulted in the highest strength and lowest compressibility. The utilisation of the other chemicals as anolytes and DW as catholytes resulted either in strength reduction and higher compressibility or no significant changes in both the engineering properties both near the anodes and the cathodes. EK treatments also affected the values of hydraulic conductivity of the treated soils, depending on the utilised chemicals. On different molarity of PA as catholytes and DW as anolyte, ' the utilisation of 0.5 M PA resulted in the highest cohesion and lowest compressibility of the EK treated soil near the cathode. No significant changes were observed in the compressibility of the treated soils near the anodes from the utilisation of different PA concentrations. Regarding the EK parameters, the directions and quantities of net electroosmotic flows varied depending upon the chemicals used as the anolytes and catholytes. These chemicals influenced the pH of the soil-pore fluid chemistry, which determined the signs and values of zeta potential (<) during EK processing. No net flows were also observed because of isoelectric point (IEP) where < = 0 were achieved. The values of electroosmotic hydraulic conductivity (k,) varied with time and generally lower than the k, values of temperate soils reported in literatures. On different concentrations of PA as catholytes, 0.5 M PA was considered as the optimum concentration in this study because the utilisation of it produced the highest in strength, current density and net electroosmotic flow besides the lowest compressibility. X-ray fluorescence (XRF) analyses on the EK treated samples showed that the distributions of the EK-injected ions after treatments were not uniform.
format	Thesis
qualification_name	Doctor of Philosophy (PhD.)
qualification_level	Doctorate
author	Ahmad, Kamarudin
author_facet	Ahmad, Kamarudin
author_sort	Ahmad, Kamarudin
title	Improvement of a tropical residual soil by electrokinetic process
title_short	Improvement of a tropical residual soil by electrokinetic process
title_full	Improvement of a tropical residual soil by electrokinetic process
title_fullStr	Improvement of a tropical residual soil by electrokinetic process
title_full_unstemmed	Improvement of a tropical residual soil by electrokinetic process
title_sort	improvement of a tropical residual soil by electrokinetic process
granting_institution	Universiti Teknologi Malaysia, Faculty of Civil Engineering
granting_department	Faculty of Civil Engineering
publishDate	2004
url	http://eprints.utm.my/id/eprint/4611/1/KamarudinAhmadPFKA2004.pdf
_version_	1747814541936295936

Improvement of a tropical residual soil by electrokinetic process

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