Abstract
Alkaline solutions have significant effects on the mineral composition and on the microstructure of bentonite; in relevant geoenvironmental engineering applications, therefore, the properties of bentonite buffer materials must be taken into consideration in the presence of alkaline solutions. The objective of the present study was to determine the effect of alkaline conditions on the swelling of bentonite mixed with sand. Bentonite-sand mixtures were soaked in a NaOH solution and allowed to react over prescribed periods of 6, 12, and 24 months. Swelling deformation tests were conducted on the alkali-treated bentonite-sand mixtures; the swelling of the mixtures decreased significantly with increased reaction time. The fractal ec-σ relationship (ec is void ratio of bentonite, σ is vertical stress) was employed to express the swelling characteristics of the alkali-treated mixtures, wherein the swelling coefficient decreased as the bentonite content was reduced. Dissolution traces over the clay surfaces degraded the microstructural phase, thereby slightly increasing the fractal dimension. At higher dosages of bentonite, the swelling of bentonite-sand mixtures always followed a similar ec-σ relationship as that found for bentonite alone. On the contrary, in the mixtures with a small bentonite content that surpassed the designated threshold pressure, the void ratio of clay in the mixtures deviated from the ec-σ curve due to the appearance of the sand skeleton. The bentonite content for a particular bentonite-sand mixture at which deviation from the ec-σ curve began was ~50%. This deviation was almost negligible at 50% initial bentonite content in the bentonite-sand mixtures; after treatment with NaOH solution, however, a pronounced deviation in the ec-σ curve was observed which was caused mainly by the decrease in the bentonite percentage. Finally, the vertical pressure threshold was also estimated using the ec-σ relation for bentonite-sand mixtures with small bentonite contents over a range of various alkaline solution reaction times.
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References
Alonso, E.E., Vaunat, J., & Gens, A. (1999) Modeling the mechanical behavior of expansive clays. Engineering Geology, 54, 173–183.
Ashmawy, A.K., El-Hajji, D., Sotelo, N., & Muhammad, N. (2002) Hydraulic performance of untreated and polymer-treated bentonite in inorganic landfill leachates. Clays and Clay Minerals, 50, 546–552.
Bolt, G.H. (1956) Physico-chemical analysis of the compressibility of pure clays. Geotechnique, 6, 86–93.
Charpentiera, D., Devineau, K., Mosser-Ruck, R., Cathelineau, M., & Villieras, F. (2006) Bentonite-iron interactions under alkaline condition: an experimental approach. Applied Clay Science, 32, 1–13.
Chen, Y.G., Sun, Z., Cui, Y.J., Ye, W. M., & Liu, Q.H. (2019) Effect of cement solutions on the swelling pressure of compacted GMZ bentonite at different temperatures. Construction and Building Materials, 229, 116872.
Cuadros, J. & Linares, J. (1996) Experimental kinetic study of the smectite-to-illite transformation. Geochimica et Cosmochimica Acta, 60, 439–453.
Cuevas, J., De la Villa, R. V., Ramírez, S., Sánchez, L., Fernández, R., & Leguey, S. (2006) The alkaline reaction of FEBEX bentonite: a contribution to the study of the performance of bentonite/concrete engineered barrier systems. Journal of Iberian Geology, 32, 151–174.
Cuisinier, O., Masrouri, F., Pelletier, M., Villieras, F., & Mosser-Ruck, R. (2008) Microstructure of a compacted soil submitted to an alkaline plume. Applied Clay Science, 40, 159–170.
Du, Y.J., Fan, R.D., Liu, S.Y., Reddy, K.R., & Jin, F. (2015) Workability, compressibility and hydraulic conductivity of zeolite-amended clayey soil/calcium-bentonite backfills for slurry-trench cutoff walls. Engineering Geology, 195, 258–268.
Fernández, R., Cuevas, J., Sánchez, L., de la Villa, R.V., & Leguey, S. (2006) Reactivity of the cement–bentonite interface with alkaline solutions using transport cells. Applied Geochemistry, 21, 977–992.
Gates, W.P. & Bouazza, A. (2010) Bentonite transformations in strongly alkaline solutions. Geotextiles & Geomembranes, 28, 219–225.
Gaucher, E.C. & Blanc, P. (2006) Cement/clay interactions – a review: experiments, natural analogues, and modeling. Waste Manage, 26, 776–788.
Hayakawa, T., Minase, M., Fujita, K.I., & Ogawa, M. (2016) Modified method for bentonite purification and characterization; A case study using bentonite from Tsunagi Mine, Niigata, Japan. Clays and Clay Minerals, 64, 275–282.
Heikola, T., Kumpulainen, S., Vuorinen, U., Kiviranta, L., & Korkeakoski, P. (2013) Influence of alkaline (pH 8.3 – 12.0) and saline solutions on chemical, mineralogical and physical properties of two different bentonites. Clay Minerals, 48, 309–329.
Herbert, H., Kasbohm, J., Sprenger, H., Fernández, A.M., & Reichelt, C. (2008) Swelling pressures of MX-80 bentonite in solutions of different ionic strength. Physics and Chemistry of the Earth, 33, S327–S342.
Hoeks, J., Glas, H., Hofkamp, J., & Ryhiner, A. (1987) Bentonite liners for isolation of waste disposal sites. Waste Management & Research, 5, 93–105.
Karnland, O., Olsson, S., Nilsson, U., & Sellin, P. (2007) Experimentally determined swelling pressures and geochemical interactions of compacted Wyoming bentonite with highly alkaline solutions. Physics and Chemistry of the Earth, 32, 275–286.
Komine, H. & Ogata, N. (1996) Prediction for swelling characteristics of compacted bentonite. Canadian Geotechnical Journal, 33, 11–22.
Mollins, L.H., Stewart, D.I., & Cousens, T.W. (1996) Predicting the properties of bentonite-sand mixtures. Clay Minerals, 31, 243–252.
Nakayama, S., Sakamoto, Y., Yamaguchi, T., Akai, M., Tanaka, T., Sato, T., & Iida, Y. (2004) Dissolution of montmorillonite in compacted bentonite by highly alkaline aqueous solutions and diffusivity of hydroxide ions. Applied Clay Science, 27, 53–65.
Ramı́rez, S., Cuevas, J., Vigil, R., & Leguey, S. (2002) Hydrothermal alteration of “La Serrata” bentonite (Almeria, Spain) by alkaline solutions. Applied Clay Science, 21, 257–269.
Roscoe, K.H. & Burland, J.B. (1968) On the generalized stress–strain behaviour of the ‘wet’ clay. Pp. 535–609 in: Engineering Plasticity (J. Heyman and F.A. Leckie, editors). Cambridge University Press, Cambridge, UK.
Sánchez, L., Cuevas, J., Ramírez, S., De León, D.R., Fernández, R., Villa, R.V.D., & Leguey, S. (2006) Reaction kinetics of FEBEX bentonite in hyperalkaline conditions resembling the cement–bentonite interface. Applied Clay Science, 33, 125–141.
Savage, D., Walker, C., Arthur, R., Rochelle, C., Oda, C., & Takase, H. (2007) Alteration of bentonite by hyperalkaline fluids: A review of the role of secondary minerals. Physics and Chemistry of the Earth, Parts A/B/C, 32, 287–297.
Schanz, T. & Tripathy, S. (2009) Swelling pressures of a divalent-rich bentonite: diffuse double layer theory revisited. Water Resources Research, 45, W00C12.
Studds, P.G., Stewart, D.I., & Cousens, T.W. (1998) The effects of salt solutions on the properties of bentonite-sand mixtures. Clay Minerals, 33, 651–660.
Sun, D.A., Cui, H., & Sun, W. (2009) Swelling of compacted sand–bentonite mixtures. Applied Clay Science, 43, 485–492.
Sun, W.J., Wei, Z.F., Sun, D.A., Liu, S.Q., Fatahi, B., & Wang, X.Q. (2015) Evaluation of the swelling characteristics of bentonite–sand mixtures. Engineering Geology, 199, 1–11.
Tripathy, S., Sridharan, A., & Schanz, T. (2004) Swelling pressures of compacted bentonites from diffuse double layer theory. Canadian Geotechnical Journal, 41, 437–450.
Villar, M.V. (2007) Water retention of two natural compacted bentonites. Clays and Clay Minerals, 55, 311–322.
Wang, Q., Tang, A.M., Cui, Y.J., Delage, P., & Gatmiri, B. (2012). Experimental study on the swelling behavior of bentonite/claystone mixture. Engineering Geology, 124, 59–66.
Xiang, G.S., Yu, F., Xu, Y.F., Fang, Y., & Xie, S.H. (2019a) Prediction for swelling deformation of fractal-textured bentonite and its sand-mixtures in salt solution. Clay Minerals, 54, 161–167.
Xiang, G.S., Ye, W.W., Yu, F., Wang, Y., & Fang, Y. (2019b) Surface fractal dimension of bentonite affected by long-term corrosion in alkaline solution. Applied Clay Science, 175, 94–101.
Xu, Y.F., Matsuoka, H., & Sun, D.A. (2003) Swelling characteristics of fractal-textured bentonite and its mixtures. Applied Clay Science, 22, 197–209.
Xu, Y.F., Xiang, G.S., Jiang, H., Chen, T., & Chu, F.F. (2014) Role of osmotic suction in volume change of clays in salt solution. Applied Clay Science, 101, 354–361.
Yamaguchi, T., Sakamoto, Y., Akai, M., Takazawa, M., Iida, Y., Tanaka, T., & Nakayama, S. (2007) Experimental and modeling study on long-term alteration of compacted bentonite with alkaline groundwater. Physics and Chemistry of the Earth, Parts A/B/C, 32, 298–310.
Ye, W.M., He, Y., Chen, Y.G., Chen, B., & Cui, Y.J. (2016) Thermochemical effects on the smectite alteration of GMZ bentonite for deep geological repository. Environmental Earth Sciences, 75, 906.
Yong, R.N. (1999) Soil suction and soil-water potentials in swelling clays in engineered clay barriers. Engineering Geology, 54, 3–13.
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The National Natural Science Foundation of China (Grant No. 41702311) and China Postdoctoral Science Foundation (2019M660096) are acknowledged for their financial support.
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(Received 15 January 2020; revised 24 June 2020; AE: William F. Jaynes)
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Xiang, G., Ye, W. SWELLING OF BENTONITE-SAND MIXTURES AFTER LONG-TERM DISSOLUTION IN ALKALINE SOLUTION. Clays Clay Miner. 68, 491–498 (2020). https://doi.org/10.1007/s42860-020-00090-w
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DOI: https://doi.org/10.1007/s42860-020-00090-w