Observations and findings on mechanical and plasticity behavior of sand-clay mixtures
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ORIGINAL PAPER
Observations and findings on mechanical and plasticity behavior of sand-clay mixtures Eyyüb Karakan 1 & Süleyman Demir 1 Received: 19 November 2019 / Accepted: 29 July 2020 / Published online: 18 September 2020 # Saudi Society for Geosciences 2020
Abstract This paper presents effects of particle size distribution and plasticity on geotechnical properties of sand-clay mixtures. Two different clay types (kaolinite and bentonite) were mixed with different-sized clean sand at mixture ratios of 0 to 100% with increasing 10% by dry weight. An intensive series of standard compaction, Casagrande, fall cone, and plastic limit (wP) tests were performed on specimens. Experimental results showed that the maximum dry density (ρdmax) values of the mixtures increased up to 10% clay content (threshold clay content) then decreased with increasing clay content. Besides, optimum water content (ωopt) values of the mixtures decreased up to around 10–20% of clay content and then increased continuously. It was found that fall cone liquid limits were 2–4% higher than obtained from the Casagrande device. The undrained shear strength at liquid limit is approximately 2.19 kPa, but, though the undrained shear strength at plastic limit has a wide range in comparison with liquid limit (17–636 kPa), as its recommended value, 143.95 kPa was proposed by the researchers. Moreover, results also reveal that consistency limits of specimens are governed by the content and type of clay and grain size distribution of the sand-clay mixtures. Finally, some equations were proposed between various findings (i.e., optimum water content-maximum dry density, plasticity index (PI)-optimum water content, undrained shear strength (Su)-liquid limit (wL)) that were derived from the test results. Keywords Sand-clay mixtures . Standard compaction . Casagrande . Fall cone . Undrained shear strength . Plasticity effect
Introduction Formation of a soil is initiated by weathering of rocks by means of several natural events including rain, wind, and temperature changes. Such weathering forms a wide variety of soils having different size distributions (i.e., clay, silt). Accumulation of these soil caused formation of soil deposits that may consist of more than one soil type. Therefore, it is highly possible to encounter a mixing soil profile in engineering practice. Assessment of engineering behavior of such soils increases quality and reliability of design.
Responsible Editor: Zeynal Abiddin Erguler * Eyyüb Karakan [email protected] Süleyman Demir [email protected] 1
Department of Civil Engineering, Geotechnical Division, Kilis 7 Aralik University, Kilis, Turkey
Several researchers refer to transitional, composite, or binary soils for mixtures consisting of more than one soil type (Nocilla et al. 2006; Shipton and Coop 2012; Li 2013). Focusing on such soil types resulted in a wide range of laboratory experiments along with simulations by use of discrete element model (DEM) that provided a better understanding in mechanical behavior of
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