Desenvolvimento de chapas de gesso acartonado exclusivamente a partir de seus resíduos

Abstract

Plasterboard sheets are basically composed of ordinary plaster wrapped in cardboard. Waste from its application in construction must be properly disposed of, otherwise it can cause environmental impacts. The recycling of this type of waste is currently limited to incorporating small fractions of the common plaster that integrates these sheets in the production of new sheets. Cardboard waste is not reused in the recycling process and is currently being discarded. It happens that, with the increasing use of these plates, there is a need to recycle an increasing amount of this material. Thus, the general objective of this research is to evaluate the recycling process of plasterboard waste on a bench scale, producing new sheets only with this waste. Plaster and lining paper from gypsum plasterboard waste were recycled to produce new recycled sheets. The experiment included the crushing, calcination, rehydration, formation and breaking of specimens molded only with recycled plaster from plasterboard residues. The physical-chemical characteristics of the powder, the mechanical properties in the fresh and hardened states were determined, in addition to characterizing the microstructure and chemical composition of the recycled plaster. Plasterboard waste paper was recycled, determining its physical and mechanical characteristics. Recycled plasterboard sheets were produced and the physical and mechanical characteristics were determined. The grinding process proved to be efficient, because in addition to presenting granulometry above 90% through the 0.29 mm opening sieve, the unit mass of the recycled plaster showed a value of 657.37 g cm-3, above 600 kg cm- 3 stipulated in NBR 13207: 2017 of 600 kg cm-3. As for chemical requirements, the recycled plaster showed values below 1.3% for free water and 4.4% for crystallization water. The setting time met the plaster for coating criteria, with the start of setting after 10 minutes and the end of setting after 35 minutes. The recycled plaster obtained 9.3 MPa in the mechanical requirement axial compression, 3.25 MPa in split tensile strength, values greater than 20 N mm-² for the surface hardness and 0.27 MPa in the adhesion resistance, supplying all mechanical requirements of NBR 13207: 2017. It was possible to manufacture sheets of recycled cardboard only with waste cardboard coverings. Plasterboard sheets were produced that were fully recycled using recycled plaster and cardboard. 556.99 N and 443.57 N were obtained in the longitudinal and transverse flexural strength test, as well as meeting the 20 mm maximum diameter of surface hardness in the recycled plasterboard sheets. The recycled plasterboard sheet simultaneously met all the physical and mechanical requirements of NBR 14715-1: 2010.