The carbonation performance of concrete under different conditions was compared, and the carbonation velocity coefficient of three kinds of concrete under different conditions was compared, as shown in figure 5.6. The figure shows that the carbonation velocity coefficient of concrete in the outdoor environment the biggest rain. No rain in the outdoor environment next, in the indoor environment minimum. Because the environment of outdoor rain is most abominable, so the carbonation velocity coefficient maximum and outdoor rain and indoor environment is similar to (although the CO2 concentration in the indoor high, but the humidity greatly reduced). The result showed that the carbonation velocity coefficient similar.
Structures marine environment often influenced by tides and waves splashing, coupled with high humidity, high humidity conditions, the external environment is bound to affect the development of concrete carbonation. Schueremans and so on pier built in 1993 (see Figure 4.28) coring, using phenolphthalein solution determined carbonation depth measurement results shown in Table 5.1.
Without making the surface treatment of concrete missing from the data in the table shows that complete carbonization zone, which is consistent with the findings of the literature on the long-term coastal wharf storm drain drilling core analysis, by detecting the presence of a certain depth only partially carbonized area, which mainly due to the tidal zone and marina is located near the relative humidity is very high, concrete for a long time in a high state of water infiltration, in which case the effective diffusion coefficient of CO2 is very low, difficult to spread into the concrete, so the carbonation reaction does not proceed sufficiently, reduces the carbonation rate of concrete. Carbonation depth of concrete after the surface treatment to the tidal zone at 4 ~ 6mm, in the upper tidal zone to increase 8 ~ 12mm, the degree of carbonation up without a surface treatment of the concrete. The main reason is that after the silane into the concrete surface, so that the moisture content is reduced Chishui role to facilitate the diffusion of CO2 into the interior of concrete, in which case the silane permeable coatings play a role in accelerating the diffusion of CO2. Document carbonation situation after 15 years of exposure to the marine environment under the surface treated concrete was measured in a similar conclusion, as shown in Figure 5.7
It should be noted that, under the coastal environment of chloride ion erosion is the main cause of the destruction of concrete, permeable coating surface treatment despite accelerated tidal zone and concrete carbonation nearby environment, but is still relatively low degree of carbonization, not a structural deterioration in the performance of concrete the main factors.
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