Balancing workability and removability of road markings with microwave-absorbed bitumen emulsion: Performance optimization and field validation

To address the challenges of low efficiency, environmental pollution, and pavement damage associated with the frequent replacement of road marking in highway expansion and renovation projects, a novel approach utilizing microwave-absorbed bitumen emulsion (MA-BE) as a tack coat between pavement and marking was proposed. The method was investigated in combination with microwave heating technology for the non-destructive removal of marking. This study aims to address the stability challenges of MA-BE by optimizing the type of bitumen emulsion and solid content. Stability performance was assessed through solubility test, storage stability test, and energy dispersive spectroscopy (EDS)-Mapping-image processing integration. Mechanical properties were evaluated using strain sweep and binder bond strength test, while microwave heating performance was analyzed by coordinating a microwave oven with an infrared thermography camera. Field trial sections were conducted to investigate the impact of controlling the solid content of slow-breaking and fast-setting bitumen emulsions on the implementation effectiveness of the marking. The results indicated that the stability and microwave heating performance of MA-BE were significantly improved by reducing the solid content of the bitumen emulsion. However, when the solid content was reduced to 45 %, its mechanical performance decreased significantly, which may increase the damage risk of the tack coat under the loading effects. The optimal formulation was identified as MA-BE prepared with a slow-breaking and fast-setting bitumen emulsion at a solid content of 50 %, which significantly enhanced stability without negatively affecting mechanical or microwave heating performance. A synergistic balance among stability, mechanical, and microwave heating performance was achieved, effectively resolving the stability challenges of MA-BE-18 during construction. Furthermore, the marking was found to exhibit excellent durability, ease of construction, excellent economic efficiency, and a removal efficiency of up to 99.8 % in field trial sections, providing strong support for the promotion and application of this efficient, environmentally friendly, and non-damaging easy-to-remove road marking. • An easy-to-remove road marking was developed and verified by adding MA-BE tack coat. • The stability, mechanical, and microwave heating performance of MA-BE were evaluated. • Bitumen emulsion type and solid content were optimized for better performance.