Performance cement-based composite obtained by in-situ growth of organic–inorganic frameworks during the cement hydration

Cement-based materials are irreplaceable in civil engineering, and hence, there is an ongoing effort to advance their mechanical properties for broadening their utilization in different applications. Modification with polymer still has excellent potential. In this current study, a polymer-modified cement-based material with high flexural strength is prepared by in-situ atom transfer radical polymerization of acrylamide (AM). Polyacrylamide (PAM) is formed by in-situ polymerization as the cement hydrates. The AM monomer in-situ polymerizes rapidly during the first hours and slows down the early cement hydration. The mechanical properties, the microstructure, and the modification model are detailed studied. The results indicate that the proposed composites offer outstanding performance in some aspects. With the M/C ratio increasing, the flexural strength is remarkably improved, by 130% at 7d and 110% at 28d. The mechanisms of performance improvements by in-situ polymerization of AM were also examined. On the one hand, the evenly distributed cross-linked organic–inorganic frameworks, making the flexural strength of samples impressively improved as the monomer to cement ratio increases. On the other hand, due to the polymer, the presence of carboxyl functional groups produces bridged chemical bonds, which further improves the properties of the composite materials. The successful application of in-situ polymerization offers a new strategic approach to solve problems associated with concrete applications and provides technical guidance for improving of concrete structures.