Strength and Stiffness Development in Soft Soils: A FESEM aided Soil Microstructure Viewpoint

This paper opens with an overview of the debatable definition of soft soil that goes beyond a (CH) organic inorganic clay and OH peat to include weakly cemented periglacial deposits of loess and alike. It then outlines the findings obtained from stiffness test on cement-stabilised soft clay. The fin...

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Bibliographic Details
Published in:IOP conference series. Materials Science and Engineering 2016-07, Vol.136 (1), p.12041-12051
Main Authors: Wijeyesekera, D C, Ho, M H, Bai, X, Bakar, I
Format: Article
Language:English
Subjects:
Additives
Cement
Cements
Chips
Clay (material)
Compressive strength
Field emission microscopy
Formability
ground modification
Loess
Microstructure
Peat
Photomicrographs
Rubber
Sand
Soft clay
Soft soil
Soft soils
Soil (material)
Soil stabilization
Soil strength
Stiffness tests
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Summary:This paper opens with an overview of the debatable definition of soft soil that goes beyond a (CH) organic inorganic clay and OH peat to include weakly cemented periglacial deposits of loess and alike. It then outlines the findings obtained from stiffness test on cement-stabilised soft clay. The findings are complemented with a microstructure viewpoint obtained using field emission scanning electron microscope (FESEM). Research also comprised of making cylindrical stabilised clay samples, prepared in the laboratory with various rubber chips contents and cement, and then aged for 28 days. The samples were then subjected to unconfined compressive strength (UCS) test and observations were also made of its microstructure using the FESEM. The impact of the soil microstructure on the stiffness result was studied both with the stabilized soil and also of some of the natural undisturbed loess soils. Sustainability aspect and the potential of the use of rubber chips and sand as additives to cement stabilisation are also discussed. The overall test results indicated that rubber chips and sand contributed to the improvement in unconfined compressive strength (qu). The derogatory influence of moisture on the stiffness of the stabilised clay was studied simultaneously. SEM micrographs are presented that show bonding of cement, rubber chips sand and soft clay, granular units and aggregated agglomerated units in loess. The paper concludes with observations on the dependence of soil microstructure on the soil strength and deformability and even collapsibility of the loess. Current practices adopted as engineering solutions to these challenging soils are outlined.
ISSN:1757-8981
1757-899X
DOI:10.1088/1757-899X/136/1/012041