Water and Water Vapor Penetration Through Coatings

Abstract

Water and water vapor transport in two-layer systems where one layer acts as water retarder are analyzed. In the experimental work, four external paints supposed to protect the underlying structure against water under common service conditions are applied on glass fiber reinforced concrete substrates. The water absorption coefficient and the effective water vapor diffusion coefficient are chosen as evaluation parameters for the assessment of water and water vapor transport properties of the systems. In the water absorption experiments, two consecutive quasi-steady regimes are identified, the first with an almost constant water flux into the system, and the second obeying the square-root-of-time rule for cumulative mass of water in the system. The water protective qualities of all studied paints can be considered as satisfactory for common service conditions. The effective diffusion coefficients of all systems are found to be within the error range of the measuring method compared to the substrate itself, which is a very positive feature for external paints.

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References

Robbery, P.C. (1988). Requirements of Coatings , Jocca, 71: 403–406.

ISO 7783-1:96 Paints and Varnishes – Determination of Water Vapour Transmission Rate – Part I: Dish Method for Free Films.

BS 6477 (1992). Water Repellents for Masonry Surfaces, British Standards Institution .

CČerný, R. and Rovnaníkova, P. (2002). Transport Processes in Concrete, Spon Press, London.

McCarter, W.J. (1996). Assessing the Protective Qualities of Treated and Untreated Concrete Surfaces Under Cyclic Wetting and Drying , Building and Environment, 31: 551–556.

Cerný, R. , Drchalova, J. , Hoskova,S. and Toman, J. (1996). Methods for Evaluation of Water-Proofness Quality and Diffusion Properties of Coating Materials , Construction and Building Materials, 10: 547–552.

Hall, C. and Tse, T.K. (1986). Water Movement in Porous Building Materials-VII: The Sorptivity of Mortars , Building and Environment, 21: 113–118.

Ho, D.W. and Lewis, R.K. (1987). The Water Sorptivity of Concretes: The Influence of Constituents Under Continuous Curing , Durability of Building Materials, 4: 241–252.

Hall, C. and Yau, M.H.R. (1987). Water Movement in Porous Building Materials-IX: The Water Absorption and Sorptivity of Concretes , Building and Environment, 22: 77–82.

10.

Hall, C. (1989). Water Sorptivity of Mortars and Concretes: A Review, Magazine of Concrete Research, 41: 51–61.

11.

Krischer, O. (1963). Die Wissentschaftliche Grundlagen Der Trocknungstechnik, 2. Auflage, Springer Verlag, Berlin.

12.

Cerný, R. , Hoskova,S. and Toman, J. (1995). A Transient Method for Measuring the Water Vapor Diffusion in Porous Building Materials. In: de Freitas, V.P. and Abrantes, V. (eds), In: Proceedings of International Symposium on Moisture Problems in Building Walls, pp. 137–146, Univ. of Porto, Porto.

13.

Roth, A. (1976). Vacuum Technology, p. 149-149, North Holland, Amsterdam.

14.

Lide, D.L. (ed.), (1993). CRC Handbook of Chemistry and Physics, 74th Edn. p. 6–15, CRC, Boca Raton.

15.

Carslaw, H.S. and Jaeger, J.C. (1959). Conduction of Heat in Solids, Clarendon Press, Oxford.