Effect of Bentonite on Shear Strength of Bushehr Calcareous Sand
Calcareous sands are found most commonly in areas adjacent to crude oil and gas, and particularly around water. These types of soil have high compressibility due to high inter-granular porosity, irregularity, fragility, and especially crushing. Also, based on experience, it has been shown that the behavior of these types of soil is not similar to silica sand in loading. Since the destructive effects of cement on the environment are obvious, other alternatives such as bentonite are popular to be used. Bentonite has always been used commercially in civil engineering projects and according to its low hydraulic conductivity, it is used for landfills, cut-off walls, and nuclear wastelands. In the present study, unconfined compression tests in five ageing periods (1, 3, 7, 14, and 28 days) after mixing different percentages of bentonite (5%, 7.5% and 10%) with Bushehr calcareous sand were performed. The relative density considered for the specimens is 50%. Optimum water content was then added to each specimen accordingly (19%, 18.5%, and 17.5%). The sample preparation method was wet tamping and the specimens were compacted in five layers. It can be concluded from the results that as the bentonite content increases, the unconfined compression strength of the soil increases. Based on the obtained results, 3-day and 7-day ageing periods showed 30% and 50% increase in the shear strength of soil, respectively.
Digital Object Identifier (DOI): doi.org/10.5281/zenodo.3669210Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 467
 Mollins, L. H., D. I. Stewart, and T. W. Cousens. "Predicting the properties of bentonite-sand mixtures." Clay Minerals 31.2 (1996): 243-252.
 Pakbaz, Mohammad C., and Navid Khayat. "The effect of sand on strength of mixtures of bentonite-sand." Engineering Geology for Infrastructure Planning in Europe. Springer, Berlin, Heidelberg, 2004. 316-320.
 Kim, T. H., et al. "Tensile strength characteristics of contaminated and compacted sand-bentonite mixtures." Environmental geology 52.4 (2007): 653-661.
 Sun, De’an, Hongbin Cui, and Wenjing Sun. "Swelling of compacted sand–bentonite mixtures." Applied Clay Science 43.3-4 (2009): 485-492.
 Khan, Zahid, M. H. El Naggar, and Giovanni Cascante. "Frequency dependent dynamic properties from resonant column and cyclic triaxial tests." Journal of the Franklin Institute 348.7 (2011): 1363-1376.
 Wayal, A. S., N. K. Ameta, and D. G. Purohit. "Dune sand stabilization using bentonite and lime." J Eng Res Stud 3.1 (2012): 58-60.
 Salem, Manal, Hussein Elmamlouk, and Shehab Agaiby. "Static and cyclic behavior of North Coast calcareous sand in Egypt." Soil Dynamics and Earthquake Engineering 55 (2013): 83-91.
 Iravanian, Anoosheh, and Huriye Bilsel. "Strength Characterization of Sand-Bentonite Mixtures and the Effect of Cement Additives." Marine Georesources & Geotechnology 34.3 (2016): 210-218.
 Krumbein, William Christian. "Measurement and geological significance of shape and roundness of sedimentary particles." Journal of Sedimentary Research 11.2 (1941): 64-72.
 ASTM Committee D-18 on Soil and Rock. Standard Practice for Classification of Soils for Engineering Purposes (Unified Soil Classification System) 1. ASTM international, 2017.