Roles of aromatic oil, polyphosphoric acid and sulfur on the storage stability and compatibility of high-viscosity particle modified asphalt

Abstract

High-viscosity particle modified asphalt (HVPMA) is one of the most popular asphalt binders for permeable pavement in China. This commercial high-viscosity particle modifier is usually rich in styrene–butadienestyrene (SBS) polymers, which brings marked storage stability and compatibility issues to HVPMA. Hence, this study aims to investigate the roles of aromatic oils (AO), polyphosphoric acid (PPA) and sulfur on the storage stability and compatibility of HVPMA. The effects of AO, PPA and sulfur on the overall performance of HVPMA are firstly investigated by physical, rheological tests and morphological observations. Through the cigar tube test, the effects of various additives on the storage stability of HVPMA are then analyzed. Lastly, the effects of various additives on the compatibility of HVPMA are determined by the Cole-Cole plot method via frequency scan test. Morphological observations indicate that the polymer phases become swelled and smoother after adding AO, and adding the chemical stabilizers can boost the formation of the network structures. The physical and rheological results show that the combination of PPA and sulfur makes the greatest contribution to the high-temperature performance improvement of HVPMA, followed by PPA and sulfur. Separation test results reflect that adding AO has little improvement on the storage stability of HVPMA, while the storage stability of HVPMA can be significantly improved by the addition of chemical stabilizers (i.e., PPA, sulfur, or a combination of both). The accuracy of the segregation index (SI) based on rheological properties is higher than that of the traditional softening point difference (SPD) index, and the SI value based on ZSV is easier to determine the segregation status. However, it is difficult to determine the correspondence between Cole-Cole curve symmetry and compatibility due to the influence of temperature, and the Cole-Cole curve method cannot provide sufficient information to determine the compatibility of HVPMA.