Evaluation of VOCs inhibited effects and rheological properties of asphalt with high-content waste rubber powder

Waste rubber powder (WRP) has become a widely used and sustainable replacement for asphalt modifier. At present, the mixing content of WRP in waste rubber modified asphalt (WRMA) is basically between 18 and 22%, while the high-content (25-45%) WRP modified asphalt (HC-WRMA) can realize the high added value utilization of solid waste and show excellent high temperature properties at the same time. However, more volatile organic compounds (VOCs) will be generated with the increase of the content of WRP, which would lead to environment pollution. This research aimed to explore the optimal mixing content of WRP in asphalt and how to effectively suppress the VOCs produced of HC-WRMA. First, the compatibility between WRP and asphalt was analyzed for HC-WRMA. Then, different VOCs inhibitors including activated carbon, 4A zeolite and nano calcium carbonate were added into HC-WRMA to inhibit VOCs emission. In addition, the high temperature rheological properties of HC-WRMA were studied using dynamic shear rheometer (DSR) and the low temperature properties of HC-WRMA were studied using differential scanning calorimetry (DSC). The optimum contents of WRP are 35% according to the storage stability experiments results. The GC-MS results show that different inhibitors have a significant inhibited effect on asphalt VOCs, and the addition of 6% nano calcium carbonate has the best inhibited effect. The DSR results show that complex modulus of HC-WRMA increased gradually with the increase of WRP content, and the phase angle decreased with the increase of WRP content, which indicates that the addition of WRP can improve the resistance deformation ability of asphalt and enhance the flexibility of asphalt. The DSC results show that the addition of excessive WRP has adverse effect on the low temperature performance of asphalt. Also, the Fourier transform infrared spectroscopy (FT-IR) results show that there are no chemical reaction and only physical blending between the WRP and asphalt. In short, HC-WRMA has broad development prospects in the future.

Automated summary

This research investigated the performance of high-content WRP modified asphalt and methods to suppress volatile organic compounds emissions. The results showed that adding 6% nano calcium carbonate can effectively inhibit the production of volatile organic compounds in asphalt.