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Title: A geotechnical evaluation of monotonic and cyclic loading of a compacted well-graded granular material with and without cement
Author: Rezaeian, M.
ISNI:       0000 0004 7230 8717
Awarding Body: UCL (University College London)
Current Institution: University College London (University of London)
Date of Award: 2016
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Soil reinforcement has been, since the beginning of the last century, one of the most attractive type of material for engineers. It allows the soil properties to be changed to better suit the requirements of the structure being built. Despite the high embodied carbon, Portland cement is still widely used to improve the strength of soils and, more importantly, reduce the maintenance frequency of infrastructure assets, this, in return, may justify its application. In this research, a comprehensive laboratory triaxial testing programme was developed, in order to better understand the behaviour of a cemented and un-cemented crushed limestone, used as base and sub-base in UK. The material is well graded and the samples were prepared by dynamic compaction, very dense state, with 0, 1 and 2% of cement. The triaxial tests were performed under a variety of confining stresses, monotonic shearing and cyclic stress ratios. Results derived from the monotonic shearing were interpreted using critical state soil mechanics concept, including the changes in peak strength, changes in stiffness, yielding points, stress-dilatancy behaviour, etc. Similar samples were tested under a high number of cyclic loading and different stress ratios. To evaluate the effect of the cyclic shearing on the samples, monotonic shearing was performed afterwards and also interpreted in the same way. The cyclic stage was interpreted based on shakedown theory and the methodology proposed by BS EN 13286-7 (2004) in order to rank the material behaviour. It was also shown that particle breakage was as low as did not change the results. Distinct critical state lines, for different cement contents, were found, regardless of the shearing method used. The results also show that the addition of cement is beneficial to the behaviour of the soil, stabilising the mixtures by reducing the volume changes during the cyclic stage. This improves the long term performance of these materials in the long term, by reducing maintenance costs.
Supervisor: Ferreira, P. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available