Concrete Sealers and Coating Systems
Highway agencies generally agree that the most important criterion for concrete durability in the presence of highway deicing salt is high quality, air-entrained concrete. Other important factors to consider are: aggregate quality, size and type (non-reactive), cement-to-aggregate ratio (approx. 0.20), proper air-entrainment, at least three inches of concrete cover over the reinforcing steel, dense concrete with a water-to-cement ratio of 0.35 or less, epoxy-coated steel, a minimum of seven days moist curing, and properly attained strength (500 psi the first day and 4,000 psi by the 28th day).
Concrete sealers provide added protection for high quality concrete, and may extend the life of lower quality concrete. Concrete sealers are used to prevent or slow the ingress of water, chlorides, and aggressive chemicals. Many sealers exist, including Silanes, siloxanes, and siliconates, epoxies, gum resins and mineral gums, linseed oil, stearates, acrylics silicates and fluorsilicates, urethanes and polyurethanes, polyesters, chlorinated rubber, silicones, and vinyls.
According to Cady (1994), important sealer considerations and properties include: penetration depth, ultraviolet resistance, reactivity of concrete materials, service life, chloride and water absorption, water vapor transmission, crack bridging, deicer scaling resistance, etc. It is also important that the concrete surface be thoroughly dry and clean (free of any residues that might inhibit sealant penetration). Cady suggests water-repellent, pore blocking and barrier coating sealers as most suitable for highway use to delay the onset of deicer scaling and reinforcement corrosion. Based on Cady’s survey of highway agencies, the most frequently used sealers are (in percent used or approved) silane (33%), epoxy (15%), siloxane (14%), synthetic gum resins (10%), and linseed oil (9%).
The following references may be helpful for selecting concrete sealers and coating systems.
References
1990. A Guide to the Use of Waterproofing, Dampproofing, Protective, and Decorative Barrier Systems for Concrete American Concrete Institute. ACI Committee Report ACI 515.1R-79 (Revised 1985). Box 19150, Redford Station, Detroit, MI 48219-0150.
Aitken, Claire T., Litvan, Gerald G. 1989, Laboratory Investigation of Concrete Sealers. Concrete International: Design and Construction , Vol. 11, No. 11, November 1989.
Cady, Philip D. 1994. Sealers for Portland Cement Concrete Highway Facilities. National Cooperative Highway Research Program. NCHRP Synthesis 209. Transportation Research Board. National Research Council. 2101 Constitution Ave. N.W., Washington, DC 20418.
Foscante R.E., H.H. Kline. 1988. Coating Concrete - An Overview. Coatings & Linings. Materials Performance MP/September. NACE International, P.O. Box 218340, Houston, TX 77218-8340.
Hazrati, K, Abesque, C, Pigeon, M, Sedran, T. 1997. Efficiency of Sealers on the Scaling Resistance of Concrete in the Presence of Deicing Salts. RILEM Proceedings 1997, Vol. 30, No. Freeze Thaw Durability of Concrete p. 165-196.
Kamel, Amr A., Thomas D. Bush , Jr., and Arnulf P. Hagen, 1993. Silane Performance: Testing Procedures and Effect of Concrete Mix Design. Transportation Research Record No. 1382. Materials and Construction. Part 2 Developments in Concrete Technology. Transportation Research Board. National Research Council.
Marusin, Stella L. 1989, Enhancing Concrete Durability by Treatment with Sealers. Proceedings of the Sessions Related to Structural Materials at Structures Congress 1989. ASCE, New York, NY p. 270-281.
Rizzo, E.M., Bratchie, S. 1989, Use of Penetrating Sealers for the Protection of Concrete Highways and Structures. J. Protect. Coat & Linings 1989, Vol. 6, No. 1, p. 62-70.
Smutzer Richard K. and Luh-Maan Chang. 1993. Field Tests of Resistance to Chloride Ion Penetration on Sealed Concrete Pavement. Transportation Research Record No. 1382. Materials and Construction. Part 2 Developments in Concrete Technology. Transportation Research Board. National Research Council.
Sock, M.D. 1997, Durability of Penetrant-Class, Sealer-Coated, Air-Entrained Concrete Subjected to Freeze/Thaw. Rhode Island Dept. of Transportation, Providence, RI. Report No. FHWA/RI/RTD-97-1.
Steele, Jon. 1994. Coating Film Thickness in Concrete Sanitary Sewers: How Much is Enough? Coatings & Linings. Concrete Advice. Materials Performance MP/September.
Weyers, Richard E., Jerzy Zemajtis, and Rick O. Drumm,. 1995. Service Life of Concrete Sealers. Transportation Research Record 1490. Transportation Research Board Annual Meeting January 1995.
Wright, J., Rizkalla, S, Shen, Z. 1993, Three-Year Field and Laboratory Evaluation of Linseed Oil as a Concrete Sealer. Canadian J. of Civil Engineering, Vol. 20, No. 5, Oct. 1993 p. 844-854.
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