Development of plasterboard sheets exclusively from waste

Plasterboard sheets are basically composed of gypsum plaster sandwiched between two layers of paper. The residues from their application in construction must be properly disposed, otherwise they can cause environmental impacts. The recycling of this type of waste is currently limited to incorporating small fractions of the gypsum plaster that integrates these sheets in the production of new sheets. Lining paper residues are not reused in the recycling process and are currently discarded. The objective of this research is to evaluate the recycling process of gypsum plasterboard waste on a bench scale, producing new sheets only with this waste. The plaster and lining paper from the drywall plasterboard waste were recycled separately to produce new recycled sheets. The experiment included crushing, calcination, rehydration, formation and breaking of specimens. The physical-chemical characteristics of the powder, the mechanical properties in the hardened state, as well as the microstructure and chemical composition of the recycled plaster were determined. Lining paper waste was recycled, determining its physical and mechanical characteristics. Recycled plasterboard sheets were produced and the physical and mechanical characteristics were determined. The grinding process used in the study proved to be efficient, because in addition to having a granulometry of 93.00% passing through the 290 μm sieve, the unit mass of the recycled plaster showed a value of 6.57 105 kg m−3. The recycled plaster obtained 9.3 MPa in the axial compression strength, 3.25 MPa in the splitting tensile strength, values greater than 20 MPa for the surface hardness and 0.27 MPa in the adhesion resistance, taking into account all mechanical requirements of Brazilian standards. It was possible to manufacture sheets of recycled lining paper only with waste lining paper coverings. Plasterboard sheets were produced that were fully recycled with recycled gypsum plaster and recycled lining paper. The recycled gypsum plasterboard showed 11.20 kg m−2 of surface mass density. 3.09 MPa and 2.62 MPa were obtained, respectively, in the longitudinal and transversal flexural strength tests. It reached 0.016 m in surface hardness determined by the maximum dent diameter. The axial compression strength of this recycled sheet was 14.37 MPa. The recycled gypsum plasterboard simultaneously met all the physical and mechanical requirements of Brazilian technical standards. Schematic flow of production of recycle