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. 2022 Aug 30;15(17):5994.
doi: 10.3390/ma15175994.

Fluorocarbosilane-Based Protective Coatings for Concrete

Karol Szubert  1 , Agnieszka Dutkiewicz  2 , Marek Nowicki  3 , Hieronim Maciejewski  1   2
Affiliations

Fluorocarbosilane-Based Protective Coatings for Concrete

Karol Szubert et al. Materials (Basel). .

Abstract

The effectiveness of protective coatings based on 3-(2,2,3,3,4,4,5,5-octafluoropentyloxy)propyltriethoxysilane (OFTES) in protecting concrete surfaces against water was tested. For the synthesis of OFTES, 2,2,3,3,4,4,5,5-octafluoropentanol, which is a by-product in the synthesis of poly(tetrafluoroethylene), was used. The proposed silane is a cheaper alternative to the fluorinated organosilicon compounds currently used. The coatings were deposited by the sol-gel method. As a result of the creation of chemical bonds between the concrete surface and the silane, a coating was created that permanently increases the hydrophobicity of the concrete. Fluorine chains attached to silicon atoms are an effective barrier that prevents access to water and limits its impact on the concrete surface. As a result of the proposed silanization, the concrete surface obtained a hydrophobic character at contact angles of up to 126°, and the water absorption of the concrete decreased by up to 96%.

Keywords: concrete; fluorocarbosilane; organically modified silanes; protective; sol-gel processes.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
The sol-gel reaction mechanism between OFTES and the concrete surface.
Figure 2
Figure 2
SEM images of unmodified concrete (a,b) and concrete with a modified surface by OFTES solutions: sample F1 (c,d), F2.5 (e,f), and F5 (g,h).
Figure 3
Figure 3
EDS mapping of the elements on the F5 surface; element map of Si (a) and F (b).
Figure 4
Figure 4
SEM images of concrete with a modified surface by OFTES/TEOS solutions: sample F1_4 (a,b), F2.5_2.5 (c,d), F4_1(e,f), and F5_5 (g,h).
Figure 5
Figure 5
EDS mapping of the elements on the F5_5 surface; element map of Si (a) and F (b).
Figure 6
Figure 6
The WCA on the unmodified concrete surface (a) and with coating F5 (e); images of a water droplet on the unmodified surface (b–d) and with coating F5 (f–h); directly after deposition and after evaporation.
Figure 7
Figure 7
Results of penetration depth revealed by water spraying: raw photo (a) and photo after contrast adjusting (b).
Figure 8
Figure 8
SEM images of concrete with a modified surface by neutral 5% OFTES solutions (a,b); EDS mapping of the elements on the F5* surface; element map of F (c) and Si (d).
See this image and copyright information in PMC

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