Hydro-mechanical behaviour of cement kiln dust under saturated and unsaturated conditions

Karagoly, Yahya 2020. Hydro-mechanical behaviour of cement kiln dust under saturated and unsaturated conditions. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

The importance of reusing industrial wastes has been recognised to benefit the society in various ways. Waste minimisation, natural resources conservation, reducing energy cost, effective landfill utilization, and mitigating the environmental impacts are some of key issues that are directly linked with the reuse of industrial wastes. Cement kiln dust (CKD), an industrial byproduct from cement manufacturing process, has been considered as an alternative material (alone or as admixture) in various geotechnical and geoenvironmental engineering applications. Most construction materials used in various applications are compacted and hence unsaturated which in turn, may undergo wetting and drying processes due to the environmental changes. This thesis presents a comprehensive experimental investigation focusing on the hydro-mechanical behaviour of CKD. Numerous experimental techniques were used to study the volume change, compressibility, hydraulic conductivity, water retention and shear strength of a CKD. Complementary investigations were also carried out on a sand and a sand (85%)-CKD (15%) mixture. One-dimensional volume change and compressibility tests were carried out using a conventional oedometer. Pressure plate, chilled-mirror dew-point potentiameter, fixed matrix porous ceramic disc sensors, suction control oedometer, and unsaturated triaxial test set up were used to establish the water retention curves (WRCs). The shear strength parameters were determined from conventional UU, CU, CD tests and the unsaturated shear strength parameters from unsaturated CD triaxial tests. The CKD used exhibited swelling at low applied stresses and a tendency to collapse at high stresses when wetted from unsaturated condition. The swelling strain decreased with an increase in the applied stress, whereas swelling pressure developed when hydrated under constant volume condition. Some commonly used correlations between compressibility parameters and plasticity properties of clayey soils were found to be valid for the CKD. Significant scatter was noted in the experimental WRC data that were established from various devices/techniques. The popular parametric models used for best-fitting water retention data of soils were found to be suitable for CKD. The wetting WRC remained below that of the drying WRC. Consolidation of CKD influenced the shear strength parameters. The cohesion (c) was higher and the angle of internal friction (ϕ) was lower in the UU tests than in the CU tests. The maximum value of ϕ for the CKD was obtained in CD tests. The strain rate adopted during the shearing process affected the rate of development of deviator stress and the peak deviator stress, but its effect was insignificant at large axial strain. The value of apparent cohesion (c) decreased with a decrease in the matric suction. The suction – cohesion relationship was found to be non-linear, particularly at high suctions, whereas ignoring the non-linear relationship, the values of ϕ and ϕb (the angle of friction due to matric suction effect) were found to be similar. An addition of 15% CKD to sand did not significantly influence the hydraulic conductivity and (ϕ) of the sand, whereas c was found to increase.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Engineering
Uncontrolled Keywords:	Cement kiln dust; Suction; WRC; Shear strength; Volume change; Swelling; Compressibility; Permeability.
Date of First Compliant Deposit:	10 December 2020
Last Modified:	26 Oct 2021 01:34
URI:	https://orca.cardiff.ac.uk/id/eprint/136906

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