Impact of sulfate attack on mechanical properties and hydraulic conductivity of a cement-admixed clay

Context and purpose: Treatment of clay with cement has been used for various ground improvement and geoenvironmental applications including vertical barriers to isolate contaminated areas. An important issue with cement-treated clays is their durability especially when applied in chemically aggressi...

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Bibliographic Details
Published in:Applied clay science 2014-11, Vol.101, p.490-496
Main Authors: VERASTEGUI-FLORES, R. D, DI EMIDIO, G
Format: Article
Language:English
Subjects:
Cements
Clay (material)
Degradation
Earth sciences
Earth, ocean, space
Exact sciences and technology
Fluid dynamics
Fluid flow
Hydraulics
Mineralogy
Permeation
Silicates
Sulfates
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Summary:Context and purpose: Treatment of clay with cement has been used for various ground improvement and geoenvironmental applications including vertical barriers to isolate contaminated areas. An important issue with cement-treated clays is their durability especially when applied in chemically aggressive environments. The purpose of this study is to evaluate the impact of chemical degradation on engineering properties of cement-treated clay. Methodology The mechanical and hydraulic behaviors of a cement-treated clay in contact with water and an aggressive sodium sulfate solution were investigated. Bender elements were installed in a flexible-wall hydraulic conductivity cell to simultaneously monitor the small-strain shear modulus (G sub(0)) and the hydraulic conductivity (k) of the cement-admixed clay. Results: During permeation with clean water, an increase of G sub(0) and a gradual decrease of k with time were observed due to cement hydration. Conversely, after permeation with the sulfate solution, a sudden decrease of G sub(0) and a gradual increase of k were recorded. Conclusions: G sub(0) measurements provided evidence of immediate deterioration of the sample as it comes in contact with sulfates. However, in order to have significant impact on the permeability, a network of interconnected preferential flow paths had to first develop through the whole sample. Monitoring of G sub(0) was shown to provide valuable additional information to study the impact of chemical degradation of cement-treated clays.
ISSN:0169-1317
1872-9053
DOI:10.1016/j.clay.2014.09.012