Investigation on storage stability, H2S emission and rheological properties of modified asphalt with different pretreated waste rubber powder

The use of waste rubber powder (WRP) to produce WRP modified asphalt (WRMA) has been proved to have wide application prospects, however, WRMA has poor storage stability and is prone to release H2S and other toxic fumes. Therefore, the one-step method to ameliorate these two problems through pretreating WRP was proposed, and the microwave activation, waste cooking oil (WCO) swelling and acid or alkali solution soaking were applied to pretreat WRP in this study, respectively. The scanning electron microscope and infrared spectroscopy were selected to analyze the microstructures and functional groups of different pretreated WRP. The fluorescence microscopy and hot tube test were employed to evaluate the compatibility of pretreated WRP with asphalt. The H2S gas detector and gas chromatography-mass spectrometry were introduced to research the flue gas emissions of pretreated WRP and prepared WRMA. The experimental results show that the microstructure and functional groups of the pretreated WRP are greatly changed and its surface activity is increased. The storage stability of WRMA prepared with pretreated WRP is obviously improved, and the optimized result is obtained with the microwave/WCO composite treatment, with a segregation index reduction of 40.91%. Also, the pretreatment of WRP does reduce H2S and flue gas emissions. The cumulative H2S concentration reduction of WRP after NaOH solution soaked reaches 32.14% at 30 min, and the total flue gas concentration reduction of the prepared WRMA reaches 21.54%. The results could offer guidance for the clean utilization of WRP, the efficient storage of WRMA and the effective suppression of its flue gas.