Study on the characteristics and performance of nano-silica/unsaturated polyester resin composite modified asphalt waterproof adhesive layer

The waterproof adhesive layer (WAL) is a critical structure that effects the service life of bridge deck pavement. However, ordinary asphalt-based WAL materials commonly suffer from significant degradation of bond strength at high temperatures, leading to functional failure. To address this issue, this paper developed a novel WAL material by compositely modifying asphalt with nano-silica (NS) and unsaturated polyester resin (UPR). Subsequently, a comprehensive analysis of the composite modification effects of NS/UPR and the performance of composite modified asphalt as a WAL material was conducted through a series of experimental tests. The results indicated that the optimal mass ratio for the NS/UPR composite modified asphalt was coupling agent: NS: UPR: initiator: asphalt: compatibilizer = 3:3:100:4:282:4. The incorporation of NS promoted the uniform dispersion of UPR within the asphalt matrix, enhancing the toughness and high-temperature stability of the modified asphalt while mitigating the adverse impact of UPR on low-temperature cracking resistance. In terms of adhesion performance, the pull-off strength of the NS/UPR composite modified asphalt was 1.59 and 1.48 times that of the matrix asphalt and SBS modified asphalt, respectively. Durability tests further confirmed its superior weather resistance and ability to endure a greater number of load cycles. Overall, the novel WAL material developed in this paper demonstrated excellent adhesion performance at elevated temperatures together with favorable comprehensive properties, which expanding the potential applications of UPR in road engineering.