Comparison on the performance of solid coumarone-indene resin and liquid coumarone-indene resin modified asphalt

Coumarone-indene resin (CIR) has great potential for use as an asphalt modifier because of the cost-effective, high viscosity, and excellent mechanical properties. CIR is classified into two types based on polymerization degree: solid coumarone-indene resin (S-CIR) and liquid coumarone-indene resin (L-CIR). In this study, solid coumarone-indene resin modified asphalt (S-CMA) and liquid coumarone-indene resin modified asphalt (L-CMA) were prepared, and the comparison of the high-temperature performance, compatibility, aging performance, low-temperature performance, microstructure and modification mechanism of S-CMA and L-CMA was researched following the SuperPave standard. The results reveal that S-CIR is a solid resin with a high molecular weight that improves the high-temperature performance, permanent deformation resistance, and viscosity of asphalt, but impact on low-temperature performance negatively. In contrast, L-CIR is a liquid resin with low molecular weight that enhances the low-temperature properties and plasticity of asphalt, but decreases high-temperature properties. Additionally, solid resins with large molecular weight are prone to agglomeration in asphalt, while liquid resins with small molecular weight have better dispersibility, especially in high-content situations. Meanwhile, CIR exhibits good compatibility with asphalt. Based on the FTIR test results, chemical compositions and structures of S-CIR and L-CIR are similar, and physical miscibility was demonstrated between CIR and asphalt. In summary, modifier with different molecular polymerization degrees have a greater impact on modified asphalt, S-CMA has better high-temperature performance and viscosity than L-CMA, L-CMA has better low-temperature performance and plasticity than S-CMA, and S-CMA and L-CMA can be used for pavement construction in hot and cold areas respectively.