Insight into the in situ copolymerization of monomers on cement hydration and the mechanical performance of cement paste

Concrete usually possesses advantages of high compressive strength but weaknesses of low tensile strength originating from the intrinsic brittleness of cement hydrates. Here we propose a method of in situ copolymerization of monomers that use acrylic acid (AA) and acrylamide (AM) to restrain the brittleness of cement hydrates by in situ copolymerization during cement hydration and to enhance the mechanical strength of the cement matrix. Cement pastes with reinforced flexural strength and compressive strength can be obtained by modulating the fraction of AA-AM copolymer. With the polymerization reaction, a polymer skeleton was constructed in the cement matrix, followed by crosslinking with cement hydrates by the coordination between metal ions (Ca2+ and Al3+) and carboxy groups, enhancing the flexural strength and toughness of cement pastes. Our work offers a straightforward method to reduce the intrinsic brittleness of cement hydrates, providing a facile access to cementitious materials with improved flexural performance.