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Hydraulic and mechanical behaviour of cement-bentonite mixtures containing HYPER clay: impact of sulfate attack

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Abstract
Cemented clays are regularly employed as cut-off walls to isolate polluted soils or in ground improvement technologies. The objective of this research was to evaluate the performance of a polymer-treated bentonite (HYPER clay) and its impact on hydraulic and mechanical properties of cement-bentonite (CB) mixtures in contact with sulfates. In this research, bender elements were installed in a hydraulic conductivity cell, to simultaneously monitor the small-strain shear modulus (G(0)) and the hydraulic conductivity (k) of cement-bentonite mixtures. Initially, during permeation with deionized water, an increase of G0 with time was observed, due to cement hydration (hardening). Conversely, after prolonged permeation with sulfates, a decrease of G0 and a gradual increase of k are expected due to degradation of the cemented material. Preliminary results show that k of mixtures containing untreated bentonite increases due to contact with sulfates; conversely, k of mixtures containing HYPER clay remains unaffected. The stiffness modulus G0 was not significantly affected after a sulfate contact period of about 100 days in none of the cement-bentonite mixtures. More extensive monitoring is required for evaluating long-term mechanical degradation. These observations suggest that the use of polymer-treated bentonites could improve the resistance of cement-bentonite mixtures to sulfate attack maintaining a low hydraulic conductivity.
Keywords
Clay, bender element, sulfate attack, stiffness, cement, hydraulic conductivity, BENDER ELEMENT TESTS

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Chicago
Di Emidio, Gemmina, Ramiro Verastegui Flores, Claudia Scipioni, Evelina Fratalocchi, and Adam Bezuijen. 2015. “Hydraulic and Mechanical Behaviour of Cement-bentonite Mixtures Containing HYPER Clay: Impact of Sulfate Attack.” In Advances in Soil Mechanics and Geotechnical Engineering, ed. VA Rinaldi, ME Zeballos, and JJ Claria, 6:1002–1009. NIEUWE HEMWEG 6B, 1013 BG AMSTERDAM, NETHERLANDS: IOS PRESS,.
APA
Di Emidio, G., Verastegui Flores, R., Scipioni, C., Fratalocchi, E., & Bezuijen, A. (2015). Hydraulic and mechanical behaviour of cement-bentonite mixtures containing HYPER clay: impact of sulfate attack. In V. Rinaldi, M. Zeballos, & J. Claria (Eds.), Advances in Soil Mechanics and Geotechnical Engineering (Vol. 6, pp. 1002–1009). Presented at the 6th International Symposium on Deformation Characteristics of Geomaterials, NIEUWE HEMWEG 6B, 1013 BG AMSTERDAM, NETHERLANDS: IOS PRESS,.
Vancouver
1.
Di Emidio G, Verastegui Flores R, Scipioni C, Fratalocchi E, Bezuijen A. Hydraulic and mechanical behaviour of cement-bentonite mixtures containing HYPER clay: impact of sulfate attack. In: Rinaldi V, Zeballos M, Claria J, editors. Advances in Soil Mechanics and Geotechnical Engineering. NIEUWE HEMWEG 6B, 1013 BG AMSTERDAM, NETHERLANDS: IOS PRESS,; 2015. p. 1002–9.
MLA
Di Emidio, Gemmina, Ramiro Verastegui Flores, Claudia Scipioni, et al. “Hydraulic and Mechanical Behaviour of Cement-bentonite Mixtures Containing HYPER Clay: Impact of Sulfate Attack.” Advances in Soil Mechanics and Geotechnical Engineering. Ed. VA Rinaldi, ME Zeballos, & JJ Claria. Vol. 6. NIEUWE HEMWEG 6B, 1013 BG AMSTERDAM, NETHERLANDS: IOS PRESS,, 2015. 1002–1009. Print.
@inproceedings{8033495,
  abstract     = {Cemented clays are regularly employed as cut-off walls to isolate polluted soils or in ground improvement technologies. The objective of this research was to evaluate the performance of a polymer-treated bentonite (HYPER clay) and its impact on hydraulic and mechanical properties of cement-bentonite (CB) mixtures in contact with sulfates. In this research, bender elements were installed in a hydraulic conductivity cell, to simultaneously monitor the small-strain shear modulus (G(0)) and the hydraulic conductivity (k) of cement-bentonite mixtures. Initially, during permeation with deionized water, an increase of G0 with time was observed, due to cement hydration (hardening). Conversely, after prolonged permeation with sulfates, a decrease of G0 and a gradual increase of k are expected due to degradation of the cemented material. Preliminary results show that k of mixtures containing untreated bentonite increases due to contact with sulfates; conversely, k of mixtures containing HYPER clay remains unaffected. The stiffness modulus G0 was not significantly affected after a sulfate contact period of about 100 days in none of the cement-bentonite mixtures. More extensive monitoring is required for evaluating long-term mechanical degradation. These observations suggest that the use of polymer-treated bentonites could improve the resistance of cement-bentonite mixtures to sulfate attack maintaining a low hydraulic conductivity.},
  author       = {Di Emidio, Gemmina and Verastegui, Daniel and Scipioni, Claudia and Fratalocchi, Evelina and Bezuijen, Adam},
  booktitle    = {Advances in Soil Mechanics and Geotechnical Engineering},
  editor       = {Rinaldi, VA and Zeballos, ME and Claria, JJ},
  isbn         = {978-1-61499-600-2},
  keyword      = {Clay,bender element,sulfate attack,stiffness,cement,hydraulic conductivity,BENDER ELEMENT TESTS},
  language     = {eng},
  location     = {Buenos Aires, Argentina},
  pages        = {1002--1009},
  publisher    = {IOS PRESS,},
  title        = {Hydraulic and mechanical behaviour of cement-bentonite mixtures containing HYPER clay: impact of sulfate attack},
  url          = {http://dx.doi.org/10.3233/978-1-61499-601-9-1002},
  volume       = {6},
  year         = {2015},
}

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