The volume of air has been cited in technical literature as one of the most important performance indicators of asphalt paving mixtures. Air-void content is not measured directly; instead it is calculated mathematically by comparing the bulk specific gravity of a mixture with the maximum theoretical specific gravity of the mixture at the same asphalt content. The test method developed by rice (ASTM D-2041) is the most accepted means of determining maximum theoretical specific gravity. Nevertheless, agencies have used and continue to use other methods and calculations to determine this value. The purpose of this study was to compare mixture properties determined by the rice method with those determined by the method established by the texas state department of highways and public transportation (SDHPT). The SDHPT procedure is often referred to as the martin method. Data from 42 mix designs were analysed. The analysis determined that on average, use of the rice method to determine maximum theoretical specific gravity resulted in asphalt content about 0.35% Higher than did use of the Martin method. The difference in selected asphalt content derived from the two methods increased as aggregate absorption increased. The difference between the two methods proved insignificant for aggregate with low absorption capacities. The results revealed that the Martin method developed a reasonable approximation for maximum theoretical specific gravity during the mix-design phase.
Abstract