Study on Low-Temperature Performance of Polyphosphoric Acid Composite Modified Asphalt

摘要

This paper studied the low-temperature performance of different original asphalts, polyphosphoric acid (PPA), modified asphalt, and composite modified asphalts based on PPA by ductility test (5°C), penetration test (25°C), and bending beam rheometer (BBR). Finally, a comprehensive evaluation of these modified asphalts was carried out by combining the index of the performance grade (PG) and the cost of raw materials. The results showed that the low-temperature performance of the Esso 70# asphalt was improved, while the low-temperature performance of Iran 70# asphalt declined with the increase of the amount of PPA which indicated that the modification effect of PPA modified asphalt had a great relation with the chemical composition of original asphalt. Based on the PG index, the low-temperature performance of PPA+SBS increased first and then decreased. From the 5°C ductility value, the increase of PPA on the-low temperature performance of PPA+SBS was unfavorable. The softening point value indicated that PPA could improve the high-temperature performance of TB+PPA+SBS. Overall, the influence of PPA on the low-temperature performance of TB+PPA+SBS and PPA+SBS was not obvious and the performance of asphalt binder was mainly decided by TB rubber powder and SBS; TB rubber powder could significantly enhance the low-temperature performance of asphalt binders and reduce the production cost in way.