Mechanical properties and micro-mechanism of cement-based materials strengthened by in-situ organic-inorganic polymerization

Ordinary cement-based materials face defects in practical applications, such as poor tensile strength , brittleness , and high cracking risk. Compound modification has great potential to improve cement-based material structural and mechanical performance. In this paper, cement-based materials with a three-dimensional (3D) plug-in network structure are formed by in-situ organic-inorganic polymerization. Partial acrylamide (AM) monomer is inserted into the zirconium phosphate (ZrP) interlayer, and zirconium phosphate-acrylamide (ZrP-AM) composite materials are successfully prepared. During cement hydration , AM undergoes in-situ self-polymerization and co-polymerization with ZrP-AM, forming a complete plug-in network with ZrP distributed on the polymer network . Meanwhile, the plug-in network structure is closely bound to the cement matrix due to the formation of chemical bonds. In the best mix ratio design, the ZrP-PAM-modified sample with 1 wt% ZrP and 3 wt% AM has a 105% higher flexural strength than the cement paste . Moreover, due to the enhancing effect of ZrP on the cement matrix and polymer network , the flexural and compressive strengths of the modified sample increased by 28.5% and 17%, respectively, compared to the single AM modified sample with respect to the same dosage. The formation of the plug-in network structure and chemical bonds greatly enhances the mechanical strength of cement-based materials. This synergistic modification method fully exploits the modifying effects of polymers and nanomaterials and provides a novel strategy to improve the mechanical properties of cement-based materials.