Preparation and Properties of Highly Flexible Acrylic–Epoxy Resin with Self-Stratification Waterproof Material for Steel Bridge Decks

Abstract

Due to the complex construction processes, long construction cycles, poor deformation coordination, and lack of flexibility in the existing waterproof adhesive layer (WAL) for steel bridge decks, a new type of high-flexibility WAL with a self-stratifying effect was proposed. In this paper, firstly, four different low glass transition temperatures (−20°C, −15°C, −10°C, −5°C) of poly (2-ethylhexyl acrylate-co-butyl acrylate-co-methyl methacrylate-co-styrene) (EBMS) were synthesized by free radical solution polymerization. The chemical composition, glass transition temperature and molecular weight of EBMS were characterized by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry, and gel permeation chromatography. Secondly, the EBMS was physically blended with epoxy resin (E51) in different mass ratios to prepare E51/EBMS self-stratifying WAL. During the mixing process, a polyamide curing agent matching the epoxy equivalent of E51 was added. The self-stratifying behavior of WAL was studied by measurements of FTIR, scanning electron microscopy, water contact angle, and shore A hardness. At the same time, the feasibility of self-stratification was verified by surface energy theory. Thirdly, according to relevant standards, the conventional performance and road performance of WAL were measured. It was found that when E51 was mixed with –15°C EBMS, the WAL exhibited optimal comprehensive performance. Finally, the mass ratio of E51/−15°C EBMS effect on the performance of self-stratifying coatings is discussed. With an optimum mass ratio of E51/−15°C EBMS of 6∶4, the elongation at break and adhesive strength of this WAL reached 140% and 7.9 MPa, respectively, fully meeting the requirements of WAL on the steel bridge deck. Compared with commercially available WAL, EBMS/E51 WAL significantly improves low-temperature performance and elongation at break. This research is anticipated to serve as a valuable reference for the design and production of WAL for steel bridge decks.