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Title: Assessment of the possibility of stabilising Sabkha soils using oil lake residue -- Reuse of waste materials
Author: Al-Otaibi, Fahad A.
Awarding Body: Cardiff University
Current Institution: Cardiff University
Date of Award: 2006
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Abstract:
This thesis describes the experimental work undertaken to investigate the possibility of using oil lake residue to stabilise Sabkha soils in Kuwait. Sabkha is a problematic salt-encrusted soil deposited under arid conditions which cannot be used for construction in its natural condition. The oil lake residue being considered is the waste hydrocarbons resulting from the destruction of oil wells in Kuwait during the Gulf War, 1990. The oil lake residue covers an overall area of 24 km2, and represents an environmental hazard that needs to be eliminated. The experimental programme included laboratory and field testing of physical properties and strength, consolidation and leaching aspects of the natural and oil mixed Sabkha soils. A soil survey of a large area was undertaken to select representative soil samples. Sabkha soils from four main locations were selected for the detailed experimental testing. Oil residue was added to the Sabkha soils at different percentages ranging from 0% to 10%. The focus of the experimental work was towards physical and mechanical behaviours due to low clay (less than 0.5%) and organic (less than 2%) contents of the soil and high content of non-polar compounds (85%) in the oil residue. Results showed that the addition of oil residue reduced the friction between the soil particles in the range of 5% to 28% and the facilitated sliding over each other resulted in an increase in the density of the compacted Sabkha soils of between 2% to 8.5%. The UCS increased in the range of 34% to 504% of the natural values. The shear strength slightly increased with oil addition since the internal friction decreased and the cohesion intercept values increased in the range of 45% to 150%. The adsorbed oil residue on the cemented soil lumps acted as a waterproofing agent that reduced both salt dissolution by 56% of the natural soil and the long term coefficient of permeability in the range of 73% to 88%. Under soaked conditions, the improvement in strength properties were pronounced. The natural Sabkha soil disintegrated upon soaking while oil mixed Sabkha maintained its integrity. Yield stress increased in the range of 25% to 60% from the values of natural soils and compression index and collapsibility decreased in the stabilised Sabkha. Field testing on 5% stabilised compacted test beds revealed an additional increase in CBR and UCS above that of the laboratory results. Density and shear strength of field samples showed similar results as those obtained by laboratory testing. Leachability of oil from the 5% oil stabilised Sabkha soil measured in the laboratory under a hydraulic gradient of 40 was less than 1 mg/1, which can be considered very low. Leachability of oil residue in the field was undetectable. The main conclusion of the work is that the addition of 5% oil residue improved the performance of Sabkha soils especially under soaked conditions, which may result in its applications in the construction industry. These results are encouraging. However the acceptance of oil residue as a stabilising material necessitates further research and this future programme is briefly mentioned.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.583894  DOI: Not available
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