Effect of surface treatment on carbonation of concrete—— the influence of coating type

        Compares the effect of concrete carbonization coating surface treatment of outdoor environment after the rain infiltration, as shown in figure 5.13. The results showed that the treatment effect was better than that of the emulsion with the same amount of surface treatment and the same number of times. From figure 5.12 can also be seen in the same amount of 400/m L, silane gel than silane emulsion on concrete anti carbonization ability raise effective.

            In Munich, Germany in the Olympic village of test results show that the waterproof and non waterproof processing the measured the depth of the concrete carbonization is basically the same. Vrics and other test specimens without surface treatment and after surface treatment were subjected to carbonation depth measurements in a few years, and the results were basically the same as the carbonation depth.

         But the present related research conclusion is not exactly the same, most of the research show that permeable surface coating treatment, the carbonation rate of concrete reduce; but there are engineering survey showed that, after the permeable coating surface treatment and the carbonation rate of concrete to accelerate. To a large extent, this kind of difference comes from the difference of the relative humidity of the concrete inside and outside. When the humidity of the concrete is relatively small, the surface treatment may reduce the carbonization process; when the humidity is large, the surface treatment may accelerate the carbonization process. Therefore, it is necessary to refine the application of permeable coatings to the environmental conditions.

         Considering the influence factors of the surface treatment of the permeable coating, the carbonation depth of the surface treated concrete was calculated.   

    x(t)=asd√t      （5.3）

                  asd=akβercδs   （5.4）

        Type,x(t)for concrete in time t, the carbonation depth; asd for penetration type paint after surface treatment of concrete carbonation velocity coefficient; t carbonization time; ak for concrete carbonation velocity coefficient characteristic value; beta e environment influence coefficient; rc material influence coefficient; Delta s permeable coating influence coefficient.

If the rate of carbonation of concrete is less than that of the surface treated concrete, the carbonation depth of concrete is shown in Figure 5.14.

         The moisture diffusion in concrete has a great influence on its carbonization, and the surface treatment has a great influence on the moisture diffusion of concrete, so the surface treatment will affect the carbonation performance of concrete. In order to further clarify the impact mechanism of the surface treatment on the carbonation of concrete, the relevant experimental study and numerical analysis are needed to be further studied.