Influence of acrylamide in-situ polymerization on the mechanical properties and microstructure of OPC-CSA-Cs-FA quaternary system

During the process of rapid repair, the Portland cement-sulphoaluminate cement clinker-anhydrite-fly ash quaternary system exhibited weak toughness, low flexural strength, and low compactness. To solve these problems, this paper modified the quaternary system by acrylamide (AM) in-situ polymerization and investigated the effects of different AM content (0%, 2%, 3%, 4%, 5%, 6%) on the macroscopic properties of the quaternary system, such as flowability, setting time, and mechanical properties. The enhancement mechanism of the toughness and the microstructure evolution of the quaternary system was revealed by XRD, TG-DTG, FT-IR, SEM, and other tests. The results showed that the addition of AM could improve the flowability and the flexural strength of the quaternary system in the late stage, and the flexural strength of the cement specimens increased by 14.81% and 26.83% at 7 d and 28 d, respectively, when the AM dosing was 4%. Meanwhile, the toughness and flexibility of the quaternary system were also improved. The inorganic-organic interpenetrating network structure formed by the in-situ polymerization of PAM and hydration products allowed more energy to be absorbed before the damage, thus improving the overall toughness. Furthermore, PAM can form a perfect mesh structure in the cement slurry, which not only connects the AFt crystals but also acts as a bridge, which facilitates its later flexural strength improvement. The above results expand the application of the polymer in cement-based materials, effectively alleviate the stress damage of cement materials during the repair process, and further promote the application of the quaternary system in the field of rapid repair engineering.