Application of Jute Fiber for the Improvement of Subgrade Characteristics

Abstract

Improvement in subgrade has always been an area of concern to highway and geotechnical engineers. In case of a highway, a weak subgrade results in greater thickness of pavement layer which increases the cost of pavement construction. To strengthen the subgrade soil, the use of jute fiber is advantageous because they are cheap, locally available, biodegradable, and eco-friendly. Jute fiber mixed randomly with subgrade soil has significant impact on the improvement of subgrade characteristics over the last decade. Keeping this in view an experimental study was conducted on locally available soil reinforced with jute fiber. In this study the soil samples were prepared at its maximum dry density corresponding to optimum moisture content in the CBR mold with and without reinforcement. The percentage of jute fiber by dry weight of soil was taken as 0.3%, 0.6%, 0.9%, and 1.2%. In the present investigation the length of fiber was taken as 15 mm and 30 mm, and two different diameters (4 mm and 8 mm) were considered for each fiber length. From the laboratory tests the effect of jute fiber content on density of soil (optimum moisture content and maximum dry density) was observed for each length and diameter of jute fiber. It was observed that the optimum moisture content increases and the maximum dry density decreases with the increase in jute fiber content for each length and diameter of jute fiber. The laboratory CBR values of soil and soil reinforced with fiber were determined. The effects of aspect ratio (length/diameter ratio) of jute fiber on CBR value of soil were also investigated. Test results indicate that CBR value of soil increases with the increase in length of jute fiber. It was also observed that increasing the diameter of jute fiber further increases the CBR value of reinforced soil, and this increase is substantial at fiber content of 1.2% for aspect ratio of 3.75 (length = 30 mm, diameter = 8 mm).