Study on macro and micro properties of SBS-T/CRM dry mixed composite modified asphalt

This study aims to address the challenges associated with the conventional "wet process" production of SBS and CRM composite modified asphalt, characterized by complex preparation processes and high energy consumption. Through indoor low-speed mixing (simulating a dry process), we prepared varying amounts of SBS-T modifier (dry process SBS modifier, with concentrations of 0%, 3%, 4%) and CRM (concentrations of 0%, 3%, 6%, 9%, 12%). The research involved testing with three major indicators, dynamic shear rheometer (DSR) tests, and bending beam rheometer (BBR) tests to quantitatively analyze the performance changes in dry process composite modified asphalt. Additionally, atomic force microscopy (AFM) was employed to qualitatively study the microscopic structural morphology and mechanical properties of SBS-T/CRM dry process composite modified asphalt.The results indicate that with the addition of SBS-T and CRM, and an increase in concentration, the dry process composite modified asphalt exhibits improved resistance to rutting, fatigue, and low-temperature cracking. The overall performance of dry process composite asphalt surpasses that of single dry process modified asphalt. Following SBS-T and CRM modification, the asphalt surface roughness decreases, and the asphalt modulus increases, leading to a significant enhancement in microcrack resistance and elasticity. The recommended suitable dosage for dry process composite modified asphalt is 4% SBS-T + 9% CRM. •The composite modified asphalt with different SBS-T and CRM ratio was prepared by indoor simulation dry method.•Under the dry process, the two modifiers can improve the high and low temperature properties of asphalt.•The asphalt surface roughness decreases, and the DMT modulus increases, significantly enhancing crack resistance and stiffness.