The effect of different untreated granular materials as base course to the pavement life

In mechanistic empirical pavement design method, there are two criteria determined pavement failure, i.e. rut depth and area of cracks. Tensile strain at the bottom of surface course predicts number of load repetitions to reach the limit of area of cracks. Vertical compressive strain on the surface of subgrade indicates number load repetitions to make a particular ruth depth. When modulus of surface course and subgrade are constant, the quality of aggregate base influences both strains, As these strains determines the pavement life, it is possible to investigate the effect of quality of the aggregates on the pavement life. Poor quality aggregates performs better for thin pavement. Pavement with 150mm surface course, and 200-250mm base course, a poor or moderate quality of subgrade outperforms the performance of good quality subgrade. For pavement with fatigue criterion governs the pavement life, improving the quality of aggregates increases pavement life significantly. The rate of pavement life increament due to the improvement of subgrade quality is higher on pavement structures governed by rutting criterion.