INFLUENCE OF WARM MIX ASPHALT ADDITIVE AND DOSAGE RATE ON CONSTRUCTION AND PERFORMANCE OF BITUMINOUS PAVEMENTS

摘要

Warm mix asphalt (WMA) technology is an effective way to reduce emissions and save energy during asphalt paving by reducing production temperatures of hot mix asphalt (HMA). As development of WMA additives evolve, many owner-agencies do not know the effect WMA dosage rates have on moisture susceptibility, rutting resistance, and mixture compaction at different temperatures. The overall influence of time and temperature on mixture performance is also important. In this research, two versions of a commonly used WMA additive derived from the forest products industry are evaluated for performance during construction and traffic loading. Laboratory specimens with different additive contents (0%, 0.5%, and 1.0%) were compacted at different temperatures (115°C, 130°C, and 145°C), to evaluate shear capability parameters. Statistical analyses of the compaction force index (CFI) indicated the stability of asphalt mixtures at various compaction temperatures. Evaluation of moisture sensitivity and rutting performance was conducted using the indirect tensile strength test and Hamburg wheel tracking test. Improvements were realized at the 0.5% dosage level; therefore, no economic benefit is achieved by increasing the dosage level. Findings from the laboratory were tested in the field to evaluate the effect of curing time and temperature on WMA compared with HMA. A plant-produced mix included HMA and a WMA mixture produced for the same project. The WMA additive used in the plant project is the same additive used in the laboratory study. Loose mix was collected in order to evaluate the influence of curing time and temperature of a WMA mixture.