STP1200: Climate and Performance of Elastomeric Wall Coatings

    Elfring, WH
    research scientists, Rohm and Haas Company, Construction Products Research, Spring House, PA

    Rosano, WJ
    research scientists, Rohm and Haas Company, Construction Products Research, Spring House, PA

    Pages: 15    Published: Jan 1992


    Abstract

    Elastomeric wall coatings attempt to protect exterior concrete masonry walls by minimizing water penetration through surface cracks. In contrast to traditional paints, waterborne elastomeric wall coatings used in construction and restoration, are designed as functional crack-bridging membranes. These coatings are highly formulated materials containing pigments, extenders, and a resin binder. The key to the formulation is the binder, which provides the properties that enable the material to elongate and compress repeatedly without flowing apart or embrittling and cracking. A formulation's ability to perform as an elastomeric building material is strongly affected by climatic conditions. An elastomeric coating with a long product life in one geographic location may not hold up as well in another. The coating manufacturer must choose an appropriate binder and tailor his formulation to suit the climate where it will be used in order for the coating to have a long life cycle. Studies of crack width as a function of wall surface temperature have led to a simple model that allows us to predict building movement in different climates. Plotting crack width against wall surface temperature enables us to produce a building movement profile. By factoring in fatigue data for various types of coatings over moving cracks, we can begin to assess how binder type and changes in formulation impact product life cycle. Studies and tests such as these should lead to better understanding on the part of raw material suppliers, formulators, and contractors on how to design, test, and apply high performance elastomeric coatings which are long-lasting and durable.

    Keywords:

    elastomeric, coatings, temperature, climate, fatigue, waterproofing


    Paper ID: STP14887S

    Committee/Subcommittee: C24.80

    DOI: 10.1520/STP14887S


    CrossRef ASTM International is a member of CrossRef.