Title:
Protective Ability of an Acrylic-Based Surface Coating System against Chloride and Carbonation Penetration into Concrete
Author(s):
R. N. Swamy, A. K. Suryavanshi, and S. Tanikawa
Publication:
Materials Journal
Volume:
95
Issue:
2
Appears on pages(s):
101-112
Keywords:
acrylic-based coating; atmospheric carbonation; bond strength;
chloride penetration; concrete durability; concrete protection; long-term tests;
DOI:
10.14359/355
Date:
3/1/1998
Abstract:
The majority of concrete structures, particularly those in coastal environments, often suffer from both chloride and atmospheric carbonation attacks. Application of polymer-based concrete surface coating is one of the solutions available for the long-term protection of the reinforcement steel from corrosion. This paper deals with the performance of concrete slabs coated with acrylic-based coating against chloride and atmospheric carbon dioxide attacks. For this purpose, fully and partially surface-coated slabs were exposed to repeated cyclic wetting by sodium chloride solution followed by drying. After completion of the cyclic exposure regime, the slabs were exposed to laboratory drying environment and then were subjected to experimental investigations. The experimental results showed practically no chloride penetration into the concrete beneath the acrylic-based surface coating even after long-term exposure. On the other hand, for the uncoated concrete, the amount of chlorides and their depth of penetration into the concrete were found to be dependent on the water-cement ratio of the concrete. The amount of chlorides penetrating laterally, and the distance they penetrate from the uncoated concrete into the adjoining concrete below the acrylic-based surface coating is also a function of the w/c ratio of concrete. Further, both x- ray diffraction studies and phenolphthalein spray tests showed the acrylic- based coating to be very effective in controlling the carbonation of the concrete below it, especially when the coating was applied by spraying. The coating maintained good adhesion with the substrate concrete even after the long-term repetitive wetting and drying cycles.