Reduction of microplastic content, toxicity, and CO₂ footprint in façade plasters through substitution of organic binders with water glass compounds

Harmful microplastics have been increasingly detected in façade systems, posing a significant environmental concern. Ready-to-use (R2U) dispersion façade plasters are premixed plaster formulations that can be applied directly out of the container, eliminating the need for onsite mixing or preparation. We developed a new formulation for ready-to-use dispersion façade plaster, where the acrylic resin component (microplastic) was innovatively replaced with specially selected water glass. The formulation was based on conventional organic-based plasters to minimize modifications in production technology while preserving the application characteristics and aesthetic properties of standard plasters, facilitating its market introduction. To assess the usefulness of the newly developed plaster, its rheological and functional properties were compared to a commercially available plaster containing acrylic resin. Combustion tests were carried out to determine the toxicity and global warming potential of the combustion products, as well as the flammability of the material. The microscopic structure was investigated using scanning electron microscopy (SEM). The properties of the newly designed plaster were comparable to or exceeded those of commercial plaster based on acrylic resin, as evidenced by enhanced adhesion to mineral substrates, reduced water absorption, and increased vapor permeability. Furthermore, water glass-based plaster has exhibited long-term rheological stability. The novel plaster exhibited reduced flammability and toxicity, as evidenced by a 52% increase in the WLC50M toxicometric index in comparison with acrylic resin-based plaster.