RUT DEPTH POTENTIAL OF FLEXIBLE PAVEMENT LAID OVER FIBER REINFORCED SANDY SUBGRADE

Abstract

India has large tracts of land where the subgrade soil consists of uniformly graded sand or sandy loam. Most parts of western, some parts of central Rajasthan consists of desert regions and coastal regions all over the country covering an estimated two lakh square kilometer with poorly graded fine sand forming the subgrade. Normally roads have continuity in longitudinal direction of infinite length and discontinuity in its width. Because of unconfinement on its sides, the strength of the sandy subgrade will be poor. In addition to the strength, deformation, flow, erosion, and instability are the specific problems of sandy subgrade: In the recent years, the research on fiber-reinforced soils demonstrated that this material might be a practical and cost effective technique for reinforcement of subgrade soils in flexible pavements. In comparison with systematically reinforced soils, randomly distributed fiber reinforced soils offer strength isotropy and limited potential plane of weakness that can develop parallel to oriented reinforcement. With this background, an experimental study was undertaken in the laboratory to find the rut depth potential of the sandy subgrade with varying subgrade thickness by considering individual and combined effects of cement and randomly oriented fiber inclusions. From the test results, it is observed that the strength of sand has been increased due to the cement (5%) - fiber(0.5%) reinforcement. Considerable reduction in the rut depth of the sandy subgrade was observed from the wheel tracking test results, which is desirable for flexible pavements.