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Soft Soil Stabilisation Using High Calcium Waste Material Ash

Jafer, HM and Atherton, W and Ruddock, F (2015) Soft Soil Stabilisation Using High Calcium Waste Material Ash. In: 12th International Post-Graduate Research Conference 2015, 10 June 2015 - 12 June 2015, Salford, Manchester UK. (Unpublished)

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Abstract

Civil engineering projects located in areas with soft soil present some of the most common problems in many parts of the world. Depending on the nature of the project, expensive solutions are sometimes used, which commonly involves the removal and replacement of the weak soils. Alternatively, ground improvement is now considered the best solution for such problems. Soil improvement can be achieved either by mechanical and/or chemical stabilisation. To reduce the use of cement and lime as the most traditional stabilizers applied to soft soils, sustainable waste materials have been increasingly used for soil stabilisation. This paper presents the results of a laboratory study on the stabilisation of silty clayey soil using a waste material fly ash (FA) with high calcium content produced from the incineration processes in domestic power stations. The FA used in this study has a high content of calcium oxide CaO and suitable content of silicon dioxide SiO2 (more than 25%). These cementitious and pozzolanic properties are responsible for the self-cementing characteristics of this fly ash. An intermediate plasticity silty clayey soil with medium organic matter content has been used in this study. The effect of FA on the physical and engineering properties on the selected soil such as the consistency limits, compaction characteristics (optimum moisture content and maximum dry density), and soil strength (unconfined compressive strength (UCS)), has been investigated. Different percentages of fly ash were added to the soft soil (1.5, 3, 6, 9, 12, and 15%) to produce different admixtures. Improvement levels were evaluated dependant on the UCS tests carried out on specimens at different periods of curing (zero, 7, 14, and 28 days). Results indicated that the maximum dry density decreased and the optimum moisture content increased with the increase of the FA content. In terms of the UCS tests, the results yielded the optimum value of the FA used in this study to be 12.0%, as this percentage decreased the index of plasticity (IP) significantly. The results of this study indicated that the use of this waste material could produce a significant cementitious reaction when added to the soil, and it could be used as a supplementary cementitious material.

Item Type: Conference or Workshop Item (Paper)
Subjects: T Technology > TA Engineering (General). Civil engineering (General)
Divisions: Built Environment
Civil Engineering
Date Deposited: 01 Sep 2016 08:28
Last Modified: 10 Jul 2017 10:40
URI: http://researchonline.ljmu.ac.uk/id/eprint/3967

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