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41 NACE INTERNATIONAL: VOL. 56, NO. 4 MATERIALS PERFORMANCE APRIL 2017 TABLE 1. RESULTS OF THE CHLORIDE ION PENETRATION DEPTH Reference Acrylic (S3) Silane (S1) Silane (S2) Average chloride penetration depth (mm) 32.4 24.5 11.5 11.2 Maximum chloride penetration depth (mm) 41.2 24.6 15.2 15 (a) (b) FIGURE 2 Samples of the concrete specimens were evaluated visually. FIGURE 3 Chloride diffusion coefficients in treated and untreated concrete systems. penetration of the water in the concrete, also impeded the diffusion of chloride ions. No significant differences were observed in chloride dif fusion coef ficient values between S1 and S2. Similar results were obser ved in the chloride ion penetration depth, as shown in Table 1. The silane-treated samples were far more resistant to chloride penetration when compared to the other samples. The concrete containing a larger amount of silane coating (S2) tended to yield slightly lower chloride ion permeation depth than the concrete with a smaller amount of silane coating (S1). Consequently, the silane-coated speci- mens showed the greatest impediment to chloride ion migration when compared to both the acrylic-coated and the non-coated concrete specimens. Carbonation Depth Figure 4 plots the carbonation depths determined by the RILEM carbonation test. Experimental results revealed that the car- bonation depth in the coated specimens was less than that for the noncoated speci- mens of the same age. There was a large dif ference in ef fi- ciency depending on the treatment used. The carbonation depth for the specimens that received silane coating was less than that observed with the acrylic-coated spec- imen. It can be explained that a polymer chain, built from Si-O-Si bonds that have a high resistance to chemical and thermal action, forms the basic skeleton of silane coatings. Since the energ y required to break the Si-O bond is high, the silanes are resistant to UV irradiation. 13 Additionally, th e stron g Si-O ch emical str ucture of silanes gives the material its unique perfor- mance properties, chemical resistance, good electrical properties and ozone, car- bonation, and oxidation resistance. The silane treatments (S1 and S2) pro- vided the greatest carbonation protection over the 56-day test period . The silane water emulsion with 150 g/m 2 (S1) reduced the carbonation depth by 50% after 56 days. The silane treatment with 300 g/m 2 (S2) reduced the carbonation depth by 55%, indicating that the amount of the silane material did not greatly influence the car- bonation depth. Silane Treatment Effective for Concrete Durability