Relationship of Plasticity Index of Soil with Laboratory and Field Electrical Resistivity Values Syed Baharom Syed Osman, Fahad Irfan Siddiqui, Mohammad Yaakob Behan University Technology Petronas, Sri Iskandar, Perak, Malaysia, 31750 Mehran University of Engineering and Technology, Jamshoro, Pakistan, 76062 Mehran University of Engineering and Technology, Jamshoro, Pakistan, 76062 sybaharom@petronas.com.my, fahad_03mn@hotmail.com, Keywords: Correlations, electrical resistivity, non-destructive testing, plasticity index. Abstract. Borehole sampling and laboratory soil characterizations provide accurate engineering properties, yet it is time-consuming and expensive. Geo-electrical survey is an attractive tool for delineating subsurface properties without soil disturbance. The primary objective of the current research work is to investigate the relationship between electrical resistivity and plasticity index of soil. The results from electrical resistivity tests (field and laboratory) and Atterburg limit tests were analyzed to understand the relationship between electrical resistivity and plasticity index of soil. Plasticity index have a significant correlation with field and laboratory electrical resistivity values for all soil samples. It was found that silty sand soil samples are characterized by higher plasticity index and lower resistivity values whereas sandy soil samples have lower plasticity index and higher resistivity values. Introduction Determination of physical properties of soil involves extensive soil boring, samples acquisition, laboratory testing etc. which consume a lot of time and money. Geophysical methods such as geoelectrical, ground penetrating radar, seismic refraction, etc. have become increasingly practiced in engineering site characterization as being non-invasive, non-destructive, rapid and cost-effective method. Among these methods, geo-electrical survey is a very attractive tool for delineating subsurface properties without soil disturbance [1]. Several attempts have been made by many researchers to explore the phenomenon of electrical resistivity in soils and its relationship with other soil properties; such as water content, thermal resistivity, salinity, cation exchange capacity (CEC), hydraulic conductivity, ground water distributions etc [2-14]. A thorough study of geotechnical properties and resistivity of Pusan clay deposits was conducted by Giao et al. [15]. Both field and laboratory resistivity survey were performed to study the relationship between resistivity and various properties of clayey soil, such as salinity, unit weight, moisture content, organic content and plasticity index. Electrical resistivity values ranged from 1 to 3 ohm.m except in one of the boreholes which was around 10 to 15 ohm.m. It was found that only salinity of clay shows clear correlation with resistivity. All the other properties such as plasticity index, unit weight, and organic content shows weaker correlations. Beside Pusan clay samples, 20 clay samples collected worldwide were also tested for resistivity test in order to build database of electrical properties of clayey soil. The authors suggested to investigate more soil samples for establishing general relation between electrical resistivity and geotechnical properties. Abu Hassanein et al. [2] performed a comprehensive study on the effect of molding water content and compactive effort in soil resistivity. They also investigated relationship between soil resistivity and plasticity index and grain-size distribution. Higher resistivity values were observed at optimum dry compaction and lower values obtained at wet optimum compaction. A curvilinear relationship between plasticity index and electrical resistivity of clay was obtained and it was concluded that soils with higher plasticity index generally have lower electrical resistivity values. Applied Mechanics and Materials Vols. 353-356 (2013) pp 719-724 © (2013) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/AMM.353-356.719 All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP, www.ttp.net. (ID: 113.203.207.153, MSc Research Student, Civil Engineering Deptt, Universiti Teknologi PETRONAS, 31750 Tronoh Perak, Malaysia, Tronoh Perak, Malaysia-19/06/13,13:19:42)