Conditioning of asphalt paving specimens in the laboratory for the evaluation and design of mixtures includes both time and traffic effects. This paper discusses those changes of asphalt paving mixtures due to time and traffic. Mixture conditioning includes the simulation of plant aging and environmental aging, moisture damage, and traffic densification. Moisture conditioning is also an important factor to be evaluated for asphalt paving mixtures. Stripping or moisture damage is one of the detrimental characteristics of mixtures. Currently ASTM D4867 is the standardized procedure that has been developed to evaluate moisture damage of asphalt paving mixtures. This paper presents the results of the set of experiment which dealt with the conditioning behavior of the asphalt paving mixtures. In the experimental design, the asphalt paving mixtures tested were made from a water saturation condition. The main objectives of those experiments were as follows: (I) The characteristics of asphalt paving mixtures under different compactive efforts were evaluated using gyrator-y testing machine. (2) The effects of substituting baghouse fines for asphalt cement in asphalt paving mixture, while maintaining a constant volume of baghouse fines plus asphalt cement, were studied by performing indirect tensile and resilient modulus tests. (3) The effects of various methods of conditioning such as water damage upon the performance of asphalt paving mixtures were considered. (4) A statistical analysis was conducted to establish the significance and relationships among test parameters. The general laboratory procedure was used to prepare and to test the asphalt paving mixtures. All loose mixes were subjected to initial aging which simulated the production in an asphalt plant. The aging was achieved in a forced draft oven at 275 degrees F for 4 hours. The specimens were then fabricated by gyratory testing machine. (A)
Samenvatting