THE EFFECT OF MOISTURE CONTENT AND DRY DENSITY ON THE CALIFORNIA BEARING RATIO OF COHESIVE SOIL

Abstract

Of all the available methods of pavement design the California Bearing Ratio (C.B.R.) method has been found the most reliable practical means of evaluating the strength of the subgrade and construction materials, and of estimating the required thickness of pavement to satisfy a given loading. This method was originally introduced by Porter, in 1938 and was adopted by U.S. Corps of Engineers during the 1939-45 war for the construction of flexible pavements of air fields for their immediate use. The method of design is still being used as a standard method for pavement in many countries of the world including Pakistan. Although the test procedure is simple but it is difficult to arrive at a definite C. B. R. value for any soil because the change in moisture content and drainage conditions of the soils have considerable effects on the C.B.R. value. This study was carried out to investigate the effects of moisture content and dry density on the C.B.R. value of cohesive soil at Peshawar. The experimental results in terms of C.B.R., moisture content and dry density of the soil were used to establish relationships between various parameters.