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Swell–Shrink Behavior of Rubberized Expansive Clays during Alternate Wetting and Drying

1
School of Civil, Environmental and Mining Engineering, The University of Adelaide, Adelaide, SA 5005, Australia
2
Department of Infrastructure Engineering, The University of Melbourne, Parkville, VIC 3010, Australia
3
School of Engineering and Technology, Central Queensland University, Melbourne, VIC 3000, Australia
4
Department of Civil Engineering, The University of Ottawa, Ottawa, ON K1N 6N5, Canada
*
Authors to whom correspondence should be addressed.
Minerals 2019, 9(4), 224; https://doi.org/10.3390/min9040224
Received: 18 March 2019 / Revised: 31 March 2019 / Accepted: 6 April 2019 / Published: 9 April 2019
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Abstract

The present study examines rubber’s capacity of improving the swell–shrink potential of expansive clays. Two rubber types of fine and coarse categories with different geometrical features were considered. The test program consisted of standard Proctor compaction and cyclic wetting–drying tests. Scanning electron microscopy (SEM) analysis was also performed to identify the soil–rubber amending mechanisms, and to observe the evolution of fabric in response to alternate wetting and drying. Cyclic wetting–drying led to the reconstruction of the soil/soil–rubber microstructure by way of inducing aggregation and cementation of the soil grains. The greater the number of applied cycles, the lower the swell–shrink features, following a monotonically decreasing trend, with the rubberized blends holding a notable advantage over the virgin soil. The tendency for reduction, however, was in favor of a larger rubber size, and more importantly the rubber’s elongated form factor; thus, predicating a rubber size/shape-dependent amending mechanism. The soil–rubber amending mechanisms were discussed in three aspects—increase in non-expansive content, frictional resistance generated as a result of soil–rubber contact, and mechanical interlocking of rubber particles and soil grains. The swell–shrink patterns/paths indicated an expansive accumulated deformation for the virgin soil, whereas the rubberized blends manifested a relatively neutral deformational state, thereby corroborating the rubber’s capacity to counteract the heave and/or settlement incurred by alternate wetting and drying. View Full-Text
Keywords: expansive clay; rubber size/shape; cyclic wetting–drying; swell–shrink potential; accumulated deformation; frictional resistance; mechanical interlocking expansive clay; rubber size/shape; cyclic wetting–drying; swell–shrink potential; accumulated deformation; frictional resistance; mechanical interlocking
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).
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Soltani, A.; Deng, A.; Taheri, A.; Mirzababaei, M.; Vanapalli, S.K. Swell–Shrink Behavior of Rubberized Expansive Clays during Alternate Wetting and Drying. Minerals 2019, 9, 224.

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