Different organic treatments of natural bentonite and their effects on the road and aging performance of SBS modified asphalt mixtures

In this study, three distinct types of organically modified bentonites (KH560-Bentonite, DC5700-Bentonite and Fluid-like-Bentonite) were successfully prepared through different organic treatments of cost-effective natural bentonite using γ-(2,3-epoxypropoxy)propytrimethoxysilane (KH560), 3-(trimethoxysilyl propyl) dimethyl octadecyl ammonium chloride (DC5700) and nonylphenol polyoxyethylene ether sodium sulfate (NPES) as modifiers. A systematic investigation and comparative analysis were conducted to evaluate the effects of various organically modified bentonites on the road performance and aging characteristics of SBS-modified asphalt mixtures (PmAM). The results demonstrate that organically modified bentonite improves the Marshall stability of PmAM by 1.24~2.93 kN compared to unmodified bentonite, while simultaneously enhancing its high-temperature deformation resistance. The organic treatments with different modification methods effectively improved the dispersion of bentonite in the matrix and reduced stress concentration. Notably, the flexible long-chain structure of Fluid-like-Bentonite significantly enhanced the low-temperature performance of the mixture. In terms of water stability, the organically modified bentonite improved the immersion residual stability to 86.1%~92.3%, as its lamellar structure effectively inhibits moisture penetration within the asphalt mixture. Long term aging test shows that organically modified bentonites can significantly delay the deterioration of PmAM performance and improve the anti-aging ability of PmAM. Based on comprehensive analysis of PmAM performance before and after aging, the three types of organically modified bentonites exhibited varying degrees of improvement on both road performance and aging resistance of PmAM, with the enhancement effectiveness following the order: Fluid-like-Bentonite > DC5700-Bentonite > KH560-Bentonite. This study provides significant theoretical support and technical guidance for the development of high-performance asphalt pavement materials.