High temperature rheological properties of APAO and EVA compound modified asphalt

Abstract

This study aims to explore the laboratory performance of APAO (Amorphous Poly Alpha Olefin) and EVA (ethylene-vinyl acetate copolymer) compound modified asphalt. Four EVA concentrations (i.e., 0%, 2%, 4%, and 6% by the weight of base asphalt) and four APAO concentrations (i.e., 0%, 2%, 4%, and 6% by the weight of base asphalt) were selected. Conventional tests (penetration, softening point, ductility and viscosity) were conducted. Frequency sweep, temperature sweep and multiple stress creep recovery (MSCR) tests were carried out to investigate the rheological properties of the asphalt binders and the storage stability was measured by cigar tube tests. The aging effect was evaluated by using dynamic shear rheometer (DSR) testing results. Fourier transform infrared spectroscopy (FTIR) test was used to study the chemical reaction of the asphalt. The results represented that the addition of additives (i.e., APAO and EVA) decreased the nonrecoverable creep compliance and aging index while increased softening point, elastic recovery, complex modulus and recovery rates, which indicating that APAO and EVA enhanced the high temperature properties of asphalt. Specially, in the ductility test at 5℃, the addition of APAO/EVA greatly improved the crack resistance at low temperature. The increasing VTS (viscosity-temperature susceptibility) indicated the additives enhanced the resistance to temperature susceptibility of this compound modified asphalt. Besides, the binder with APAO is better than that with EVA alone, especially in the elastic recovery and aging effect. Besides, the storage stability test results showed that the increase of APAO improved the stability of asphalt and the compound modified asphalt binders showed good resistance to cracking at low temperature in ductility test at 5 °C. The FTIR test showed that chemical reactions might happen during the mixing process of asphalt.