International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395 -0056 Volume: 04 Issue: 04 | Apr -2017 www.irjet.net p-ISSN: 2395-0072 © 2017, IRJET | Impact Factor value: 5.181 | ISO 9001:2008 Certified Journal | Page 2115 Study of relation of Permeability and compaction characteristics of clayey soil with specific surface area Sindhu A.R. 1 , Tiju Susan Thomas 2 1 Assistant Professor, Saintgits College Of Engineering, Pathamuttom, Kottayam, Kerala, India 2 PG student, Saintgits College Of Engineering, Pathamuttom, Kottayam, Kerala, India ---------------------------------------------------------------------***--------------------------------------------------------------------- Abstract – The arrangement of primary soil particles and its aggregation forms the soil structure. The surfaces of soil solid particles play an important role in many soil processes like adsorption, swelling, shrinking, water penetration and soil aggregation. Clay-size particles, and particularly some layer silicate minerals, contribute most of the inorganic surface area to soils. The surface area of a soil is a function of the size, shape and mineralogy of the constituent particles. The type of minerals present in soil largely determines the soil specific surface and related properties. Permeability and compaction characteristics of soil are greatly influenced by specific surface area of solid particles, since it determines the water influx and adsorption of water with increase in water content. The aim of this study is to investigate the effect of specific surface area on permeability and Standard Proctor characteristics of clayey soil. It involves determination of permeability, maximum dry density and optimum moisture content of soil samples collected from Kuttanad region and determination of specific surface area by adopting BET and BJH methods of analysis. The relationship between the parameters is investigated and an attempt is done to obtain the equation involving the parameters by linear regression. The results from the study show that relation exists between the parameters. The predictions from BET method were found to be more accurate. Key Words: Specific surface area, permeability, Compaction, Optimum moisture content, Dry density, Regression analysis 1. INTRODUCTION Physical and chemical properties of fine-grained soils, especially clays, may be greatly influenced by the amount of its surface area. Fine-grained soils differ in surface area predominantly as a result of differences in texture (grain- size distribution) and types and amounts of different clay minerals. The term DzSpecific Surface Areadz ȋSSAȌ refers to the area per unit weight of soil and is usually expressed as m 2 /g. Clay minerals differ substantially in Specific Surface Area. Non-swelling minerals, such as kaolinite, have only external surface, whereas swelling minerals like montmorillonite have a great deal of internal as well as external surface. Natural clay deposits can have a wide range of total surface area since the combination of external and internal surface areas may vary simply because of the mixed layer minerals that may exist and the variations in clay mineralogy. Additionally, the clay mineral fraction that is part of the overall grain-size distribution can vary greatly. The behavior of fine-grained soils may be explained by the relationship between surface area and other geotechnical properties. This study is more relevant in problematic soil like Kuttanad clay. Kuttanad is located in Alappuzha district of Kerala, India. It is an agricultural area and is known for underwater. The clay in this region is dark grey colour and the dominant clay minerals are kaolinite and illite. Kuttanad clay is characterized by its high compressibility and low shear strength .The low bearing capacity of the soil has lead to foundation failures and embankment failures [7]. Several studies have been done which includes determination of specific surface area employing different methods. Most of them are restricted to investigating modification of soil textural properties after soil treatment or by addition of materials or replacement of soil by other materials for the purpose of stabilization or strengthening of soil. Very few have been done to study the correlation of geotechnical properties with Specific surface area of soil, especially in clayey soil which could be problematic for stability of foundation. Based on several assumptions, Dolinar (2012) proposed a simplified method for determining the external specific surface area of non- swelling fine-grained soils[1] by an equation which relates the external specific surface area (BET-nitrogen) with percentage of clay fraction, determined by hydrometer method, and plasticity index (Atterberg). Garzon and Soto (2015) developed an improved method for determining the external specific surface area of fine-grained clay samples. Instead of percentage of clay fraction, it was proposed to use the clay mineral content estimated by XRD methods [2]. This study focuses on investigating the relationship between textural surface area and two important geotechnical properties, permeability and Standard Proctor characteristics, for clayey soil of Kuttanad region. 1.1 Clay mineralogy and Surface area The surface area of a soil is a function of the size, shape and mineralogy of the constituent particles. The specific surface of a soil is defined as the area (in square meters) per