Effect of vacuum-vibration-compaction molding on the properties and performances of polymer-modified cementitious material

The addition of polymers to cementitious materials can significantly enhance the water resistance of building structures operating under complex environments. The organic-inorganic cross-linked network established between the functional groups of polymers and inorganic materials significantly influences the properties of the matrix material. However, the gas-entrapping effect of polymers can have a detrimental effect on the pore structure of the paste, and the degree of organic-inorganic chemical reaction can impose a limitation on the use of polymers in cementitious materials. In this study, the vacuum-vibration-compaction (VVC) molding method was employed to improve the pore structure of the cement paste and to encourage organic-inorganic chemical reactions. The addition of the polymer did not significantly harm the pore structure compared to the paste obtained through the ordinary molding method. Consequently, in the VVC molding method, the addition of 5 wt % polymer significantly raised the content of Ca(COOH)2, a product of organic-inorganic chemical reaction, by 40.1 % and amplified the molecular chain length of the C-S-H structure by 39.0 % compared to the ordinary molding method. Furthermore, the polymer reduced water absorption by up to 66.0 %. Therefore, the VVC molding method can enhance waterproof of cementitious materials more efficiently with the use of polymers.