A study on the effects of lime on the mechanical properties and behaviour of London clay

PhD Thesis


Kichou, Z (2015). A study on the effects of lime on the mechanical properties and behaviour of London clay. PhD Thesis London South Bank University School of Built Environment and Architecture
AuthorsKichou, Z
TypePhD Thesis
Abstract

Lime is commonly used as a stabiliser to improve the engineering properties of soils in
particular for roads and pavement foundation. Despite the popularity of the technique, only
a limited amount of existing experimental data for lime treated soils from advanced testing
is available, in part due to the length of the tests. As lime stabilisation is increasingly used
for other engineering applications (e.g. embankments, railway layers, canal linings, earth
dams, buildings...etc), advanced testing to describe the mechanical behaviour of the treated
soils is required.
In this research a comprehensive experimental program was carried out to investigate the
engineering properties and behaviour of a lime treated high plasticity clay (London Clay).
A number of Unconsolidated Undrained (UU), Consolidated Drained (CD) and
Consolidated Undrained (CU) triaxial tests were performed to identify the effect of lime
dosage, compaction water content and curing time on the shear strength parameters, stressstrain
behaviour, volumetric response and dilation of the treated soil. Moreover the study
focused on understanding the mineralogical and physicochemical transformations
occurring during the curing stage. Based on a number of additional tests (XRD analysis,
pH measurement and other chemical testing) they provided a useful reference for the
interpretation of the triaxial test results; in order to support hypotheses made on the
evolution of the chemical reactions and the development of cementation bonds.
Results from CD tests showed that yield, peak, and ultimate strength were greatly
improved by an increase in lime content. London Clay samples treated with lime showed a
considerable increase in peak stress ratio ( ) peak q / , particularly at lime addition beyond p'
the initial consumption of lime (ICL). An increase in the angle of shearing resistance and
cohesion intercept with increasing lime content was observed consistently. The stress–
strain behaviour of treated London Clay was observed to be nonlinear with a contractive–
dilative response. This response is found to be strongly influenced by lime content and the
curing period. An increase in dilation with lime amount as well as a progressive
suppression in the dilation by the effective stress increase was also observed. A Critical
State Soil Mechanics (CSSM) framework was used to interpret the results. Lime addition,
curing time and compaction water content were observed to have an impact on the critical
iv
state parameters in the compression plane (v − p'). However, the overall critical state line
(CSL) in the stress space (q − p') of lime treated London Clay appears to be almost
parallel to untreated London Clay CSL at the same M value, but lying above the untreated
CSL with a cohesion intercept. Moreover, the domain where the untreated soil subsists was
observed to expand with lime addition and further enlarge with an increase in the lime
content. These features can be further explored by deriving a suitable constitutive model
for predicting the mechanical behaviour of lime treated soils.

Year2015
PublisherLondon South Bank University
Digital Object Identifier (DOI)doi:10.18744/PUB.001779
Publication dates
Print01 Dec 2015
Publication process dates
Deposited29 Jan 2018
Publisher's version
License
CC BY 4.0
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https://openresearch.lsbu.ac.uk/item/87586

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