Influence of tire rubber waste on the fire behavior of gypsum coatings of construction and structural elements

The addition of inorganic expanded aggregates, such as perlite or vermiculite is well known in gypsum plasters. However, the reuse of organic wastes in coatings like plasters and renders has been poorly studied. This paper shows the effect of tire rubber wastes on the mechanical properties and fire performance of gypsum plasters. The rubber waste was added to the mixture in mass percentages of 14.50% (C1) and 46.60% (C2). Flexural and compressive strength of plasters made with rubber wastes was visibly reduced as well as their surface hardness (Shore C). In addition, fire tests produced major damages through the entire 2 cm thickness of samples containing rubber wastes, as it was corroborated by X ray diffraction (XRD) and Thermogravimetric (TG) analysis. The heat transfer due to fire exposure modified considerably the chemical composition of plasters, since, on the non-exposed face to fire, the amount of gypsum (CaSO4·2H2O) equivalent to mass loss obtained by TG due to water released by these plasters made with rubber wastes, was 5.4-7.2 lower than that of conventional plasters. The results suggest that certain wastes may reduce the efficiency of gypsum plasters in protecting underneath construction and structural elements against fire.