Stabilisation of sulphide rich soil: problems and solutions
type: CreativeWork
description: The research presented in this thesis can be split into two well-defined areas. Firstly, the effects of the addition of lime (either 2%, 4%, 6% or 8%Ca(OH)2 or 1.5%, 3%, 4.5% or 6%CaO) on various engineering properties of a sulphide (pyrites) rich, naturally occurring clay - Lower Oxford Clay (LOC) - were studied. Experimental tests representing, or relating to, tests outlined in the Design and Construction of Lime Stabilised Capping Specification (DoT, 1995) were utilised and consisted of Atterberg (consistency) tests, compaction tests, unconfined compressive strength tests, linear expansion measurements and durability tests. Also, sulphate (S03) analyses, pH measurements, differential thermogravinietric (DTG) analyses and X-ray diffraction (XRD) tests were employed to confirm experimental data. Environmental conditions were chosen to reflect temperatures experienced in the UK - between 5*C, 10'C and 201C. The majority of samples were mellowed (the time delay between initial mixing and compaction) for 3 days at 201C prior to testing. The results show that small additions of lime (i. e. 2%Ca(OH)2 or 1.5%CaO) modify the engineering properties of LOC by causing flocculation, and also increase S03 levels due to increased gypsum levels via pyrites oxidation. However, strength development is poor as little cementitious bonding is formed. Mellowing further modifies the engineering properties as the increased time allows greater flocculation leading to a less dense, more porous material. Also ettringite forms during mellowing allowing expansive reactions to occur prior to compaction, consuming both calcium and sulphate in the process and leading to slightly reduced pH levels compared to similar unmellowed samples. Further additions of lime give further change to the engineering properties of the LOC, up to an addition of 6%Ca(OH)2 or 4.5%CaO. Further additions result only in supplying an excess of calcium. Strength development is improved with increasing lime additions, es…
abstract: The research presented in this thesis can be split into two well-defined areas. Firstly, the effects of the addition of lime (either 2%, 4%, 6% or 8%Ca(OH)2 or 1.5%, 3%, 4.5% or 6%CaO) on various engineering properties of a sulphide (pyrites) rich, naturally occurring clay - Lower Oxford Clay (LOC) - were studied. Experimental tests representing, or relating to, tests outlined in the Design and Construction of Lime Stabilised Capping Specification (DoT, 1995) were utilised and consisted of Atterberg (consistency) tests, compaction tests, unconfined compressive strength tests, linear expansion measurements and durability tests. Also, sulphate (S03) analyses, pH measurements, differential thermogravinietric (DTG) analyses and X-ray diffraction (XRD) tests were employed to confirm experimental data. Environmental conditions were chosen to reflect temperatures experienced in the UK - between 5*C, 10'C and 201C. The majority of samples were mellowed (the time delay between initial mixing and compaction) for 3 days at 201C prior to testing. The results show that small additions of lime (i. e. 2%Ca(OH)2 or 1.5%CaO) modify the engineering properties of LOC by causing flocculation, and also increase S03 levels due to increased gypsum levels via pyrites oxidation. However, strength development is poor as little cementitious bonding is formed. Mellowing further modifies the engineering properties as the increased time allows greater flocculation leading to a less dense, more porous material. Also ettringite forms during mellowing allowing expansive reactions to occur prior to compaction, consuming both calcium and sulphate in the process and leading to slightly reduced pH levels compared to similar unmellowed samples. Further additions of lime give further change to the engineering properties of the LOC, up to an addition of 6%Ca(OH)2 or 4.5%CaO. Further additions result only in supplying an excess of calcium. Strength development is improved with increasing lime additions, es…
author: Thomas, Bari Ian
language: eng
keywords: Soil stabilization
date published: 2001-12
date modified: 2026-07-24T04:38:39Z
provider: University of South Wales
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of South Wales