Preparation and Characterization of SBS/CR/LNBR Composite Modified Asphalt for 3D Printing Applications

Integrating three-dimensional (3D) printing technology for road crack filling offers promising pavement construction convenience by reducing manual labor and providing better performance. However, the typical styrene-butadiene-styrene (SBS)/crumb rubber (CR) modified asphalt (SC-A) poses challenges to 3D printing due to high viscosity and heating requirements, although their road performances are superb. Liquid nitrile butadiene rubber (LNBR) can reduce the viscosity, improve the elasticity, flexibility, and adhesion of SC-A, so five LNBR types were used to investigate the feasibility of SBS/CR/LNBR composite modified asphalt (SCL-A) for 3D printing. The influence of terminal group types, content of LNBR and CR particle size were analyzed. High- and low-temperature rheology of SCL-A were evaluated using dynamic shear rheological (DSR) tests and bending beam rheological (BBR) tests, respectively. In addition, the chemical interactions and phase structure analysis revealed that the improved performance of SCL-A is due to the formation of a cross-linked network structure among CR, SBS, and LNBR. The printability of SBS/CR/CTBN composite modified asphalt (SCC-A) was tested using a plunger 3D printer. The results showed that SCC-A is not only an excellent crack repair material, but also has a more moderate printing requirements. The viscosity of SCC-A was significantly reduced, and it can be continuously extruded at the extrusion temperature of 120°C, flat temperature of 40°C, and extrusion rate of 1.3 mm/s, and it showed good formability.