Study on the Grafting Reaction and Road Performance of MAH-<i>g</i>-SBS Modified Asphalt Sealants

With the increase in service life of transportation infrastructure, highway crack repair materials have become a critical factor restricting road maintenance quality. Therefore, in order to cope with the technical bottlenecks of insufficient high-temperature stability and poor low-temperature ductility of traditional sealants, a new chemical grafting modified asphalt sealant, maleic anhydride grafted styrene-butadiene block copolymer (MAH-<i>g</i>-SBS) modified asphalt sealant, was developed. Benzoyl peroxide (BPO) was used as the initiator to generate MAH-<i>g</i>-SBS by maleic anhydride (MAH) grafting, modifying styrene-butadiene block copolymer (SBS). Through the coupling of completely randomized design and orthogonal experimental design, a MAH-<i>g</i>-SBS grafting rate prediction model was obtained by multiple nonlinear regression analysis, which considers the effects of reaction time, initiator dosage, reaction monomer dosage, and reaction temperature. Meanwhile, the significance of factors on grafting rate was clarified by the analysis of variance (ANOVA) and the prediction model validity was verified by error analysis. The prediction model and test data were both considered, and the maximum grafting rate was 20%. Simultaneously, by combining Fourier transform infrared spectroscopy (FTIR), the modification mechanism was revealed through the relationship between the carbonyl characteristic peak intensity and the road performance of the material. Subsequently, the road performances of MAH-<i>g</i>-SBS modified asphalt sealants with different grafting rates were studied by a series of laboratory tests and it was found that with the increase of grafting rate, the ductility, viscosity, and resilience recovery significantly increased and the softening point first decreased and then increased, but the cone penetration decreased. Meanwhile, based on the gray relational analysis, the grafting rate had the most significant impact on ductility and the least impact on cone penetration.