Interpretation of CBR Test Consequences for Subgrade Soil Preserved Through Geo-Grid

Abstract

The California Bearing Ratio (CBR) is a parameter for evaluation of the mechanical strength of sub grade, base course and other layers of a new carriage way. It depends on various factors and nature of soil. The service life of pavement on weaker soil sub grade is quite low due to the high compressibility and plasticity behavior of soils. Some soils possess less strength, CBR value and have high affinity to moisture content. Hence it is important to increase the strength of soil for sustainable performance of Indian roads. To increase the sub grade soil strength, geogrids are used in roads. Geogrids are cost effective polymeric materials used as soil reinforcement. It helps to increase the stability and bearing capacity of soil, enables good drainage and involves less maintenance. Increase in CBR value of the sample with use of geogrids leads to reduction in the thickness of pavement. Two soil samples are collected from the nearby construction sites. Basic tests are to be conducted on the samples to determine its engineering and index properties followed by CBR test under optimum moisture content. This paper deals with the experimental results of CBR tests on different types of sub grade soil by increasing the number of geogrid layers in each trial. This gives the optimum number of geogrid layer to attain the maximum CBR value. This paper also includes the application of CBR value in the design of flexible pavements as per IRC recommendations.