Performance evaluation of polymer latex-modified asphalt emulsion and cold recycling mixture

Emulsified asphalt cold recycled mixture is an effective type of energy-saving and environmentally friendly road-building material. However, the base emulsified asphalt exhibits limited performance. Thus, polymer latexes, including Styrene-Butadiene-Styrene block copolymer (SBS), Styrene-Butadiene Rubber (SBR), and their hybrid systems, have emerged as effective modifiers to enhance the performance of emulsified asphalt. This study provides a thorough comparison of SBS latex-modified, SBR latex-modified, and SBS/SBR hybrid latex-modified emulsified asphalts, evaluating their rheological properties, adhesion characteristics, and pavement performance of asphalt mixtures, including fatigue resistance. Three latex-modified emulsified asphalts were prepared using the post-emulsification modification process. Dynamic Shear Rheometer (DSR) analysis showed SBS-modified emulsions had a 300 % higher complex shear modulus at 60 °C than the base emulsion. Bending Beam Rheometer (BBR) tests indicated SBR-modified emulsions had a 20 % lower complex modulus at − 24 °C. Boiling water adhesion tests revealed hybrid-modified emulsions had a 55 % lower gray scale value than single latex modifications. The radar chart evaluation system not only resolved the conflict between different test results for the same performance of the mixture but also enabled a quantitative analysis of comprehensive performance. Through this analysis, the SBR latex-modified asphalt mixture was identified as having the best overall performance. The findings were applied to lower course of the cold recycling test road, with core sampling tests verifying their stability and applicability in real service conditions. This work delivers a selection strategy for polymer latex-modified emulsified asphalts, offering tailored solutions for diverse pavement service environments. • Studies pavement performance of single/hybrid latex-mod polymer cold-recycled asphalt mixes for road structural layers. • Studies comprehensive performance of cold recycled asphalt mixtures modified by direct mixing of polymer latex. • Uses improved radar chart evaluation to resolve conflicting conclusions from different test indices for the same performance. • Provides an evidence-based selection strategy for polymer latex-modified emulsified asphalt in practical engineering.