Transfer of water in the rubberized cement pastes

摘要

Waste tire rubbers were scraped and used as fllers of cement pastes in this study. The surfaces of the experimental specimens were observed on-line with a microscopy. A wetting filmfuid flow model was proposed to explain the results of the experiments. It is supposed that water films exist within the partially dried hydated cement particles. Water transfers within the water film and diffuses into the cement particles through the porous amorphous mediun. For the water film with the film thickness less than 100 nm, the disjoining or the conjoining pressure dominates the fluxof water flow. The disjoining or the conjoining pressure is produced due to the overlapping of interfacial regions. Simulation results showed that the replacenent of hydrated cement particles with rubber particles would change the Hamaker constant of the water film and therefore reduce the trunsfer flux of water. When the Hamaker constant is positive, the conjoining pressure makes the film unstable and inhabits the transfer of water to supply the need of cement hydration. The uncompleted hydration of cement will cause the cracking of the cement as observed in theerperments.