Thinner pavements designed using recycled asphalt

The main purpose of this paper is to determine and compare the design thicknesses of asphalt pavements constructed from recycled and new asphalt material. For this purpose, preliminary design charts were developed for determining the thicknesses of recycled and new asphalt pavements of similar composition. These design charts were based on the results obtained from a limited number of fatigue tests conducted in the laboratory. In these tests, cylindrical samples were examined at various temperatures, using the indirect tensile test under controlled stress condition. The values of the poisson's ratio and dynamic modulus of elasticity obtained from these tests were used as inputs, together with the properties of subgrades of various strength, into a modified chevron multi layer program to determine the pavement thicknesses. The results obtained from this limited study indicate that, for the same subgrade and equivalent axle load repetitions, the thickness of a recycled full depth asphalt pavement is smaller than that of new asphalt pavements of similar composition (a).