The properties of polymer modified concrete depend significantly on the type of polymer used and the ratio of polymer-to-cement, which is defined as the ratio of the mass of the number of polymer solids to the amount of cement. The ratio of polymer-to-cement can vary from 0 to 1/3 depending on the type of polymer used in the properties needed for the application.
There are basically two theories of why properties are improved with the polymer concrete. In the first theory, there is no chemical interaction between cement and polymer.
During the cement hydration, part of the hydrophilic polymer phase-oriented water, while the hydrophobic portion directed air phase. Drying, the hydrophobic particles fuse together and water is removed and form a film. This is basically used to form a solid polymer surface.
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In the second theory, the polymer interacts with different components and products of portland cement hydration to form new complexes. This produces a semipermeable membrane by creating reinforcement in concrete.
The chemical reaction takes place between different particle surfaces reactive polymers such as calcium ions and polyacrylic esters in the cement hydrating. This reaction can enhance the bond between the aggregate hydrate and cement. It improves the final properties of the modified cement.
In actual practice, these two theories are likely to be applicable but it depends on the type and chemical properties of polymer materials. It also depends upon the conditions present during the hydration of cement.