STP1269

    Predicting Exterior Crack-Bridging Performance of Textured Elastomeric Coatings

    Published: Jan 1996


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    Abstract

    Laboratory duplication of the exterior crack-bridging performance of textured elastomeric coatings is difficult due to low exterior deformation rates (10-4 in. (10-4 cm)/min), the cyclic nature of sample deformations (diurnal and seasonal) and the temperature variations that produce these deformations (50 mil (0.13 cm) change in crack width per 30°F (17°C) change in temperature). We are developing a test method, based on ASTM C-836, which addresses these issues and helps to predict long term exterior performance.

    Textured elastomeric films are drawn onto precracked concrete blocks and tested on an ATS (Applied Testing Systems, Inc.) instrument capable of varying crack width and temperature simultaneously. Samples are subjected to cyclic variations of crack width, from 0 to 50 to 0 mils (0 to 0.13 to 0 cm) with an accompanying temperature variation of 30°F (17°C). The rate of change of the crack width is 1×10-3 in (4×10-4cm)/min. Comparisons of ATS data to exterior crack-bridging results suggest that the modified version of ASTM C-836 may be a useful indicator of exterior performance; adaptable to a wide variety of coatings and useful as a screening tool for both polymer and formulation development.

    Since the word “textured elastomeric coating” in the title of this paperimplies elongation and recovery characteristics which a textured coating maynot have, we have adopted the term “flexible textured coating” instead.

    Keywords:

    textured elastomeric coating, flexible textured coating, crack-bridging, elongation, Climate Driven Durability Test, Applied Test Systems (ATS)


    Author Information:

    Demarest, VA
    Senior Scientist, Construction Products Research, Rohm and Haas Co., Spring House, PA

    Gordon, SJ
    Technical Assistants, Construction Products Research, Rohm and Haas Co., Spring House, PA

    Montgomery, DJ
    Technical Assistants, Construction Products Research, Rohm and Haas Co., Spring House, PA


    Paper ID: STP39213S

    Committee/Subcommittee: E06.58

    DOI: 10.1520/STP39213S


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