Study and Characterization of Gypsum Mortars Made with Phenolic Melamine Polymer Wastes from the Decorative Paper Industry

The proposed research studies the properties of gypsum mortars made with polymeric waste from the manufacturing process of high pressure laminated (HPL) thermosetting decorative panels, composed of cellulose paper layers impregnated with phenolic resins and melamine resins. The waste generated in the cutting, profiling and milling of the decorative panels is discarded and sent to landfill without a defined use. This research aims to contribute to the Circular Economy of Waste by recovering it as a raw material. Gypsum mortars are designed by adding different amounts of melamine waste. Subsequently, the properties of the mortars are studied following the technical prescriptions established in the European regulations. Firstly, the properties of the mortars in their fresh state are studied, such as the water/gypsum ratio, consistency, apparent density of the fresh mortar and setting time. Then, the properties of the hardened mortars are determined, such as the apparent density of the hardened mortar, mechanical resistance to bending and compression, adhesion, Shore C surface hardness and capillary absorption. Based on the results obtained in the tests, the viability of this type of waste is assessed for its use as a mineral aggregate to replace traditional aggregates, in order to obtain commercial gypsum mortars for use in masonry work, cladding, walls, or as a raw material for the manufacture of prefabricated materials. The results obtained show that the limit of gypsum substitution by melamine waste could be a maximum of 25%. New mortar formulations with lower substitutions would provide significant advantages in this type of ecological materials, in accordance with the technical requirements established by the applicable European regulations.