Gypsum Plaster Research Paper

The properties of the rehydrated gypsum plaster depend on several factors, such as the fineness, the purity and the energy of mixing the powder with water. These factors affect specially the setting times (Karni and Karni, 1995). The final strength depends on the size and the shape of the formed crystals and the bonding force between them, as well as on the porosity, which depends on the water/gypsum plaster (W/GP) ratio employed in the mixture (Lewry and Williamson, 1994b; Yu and Brouwers, 2011).

A high quantity of gypsum plaster wastes (GPW) is generated in civil construction activities, which is due to its fast and variable setting time. These wastes are produced during the paste mixing and application of gypsum plaster in construction and in the demolition of buildings (Nita et al., 2004). It is estimated that only the GPW generated from plasterboards achieve about 15 million tons by year in the world (Ahmed et al., 2011).

GPW can be recycled by a new cycle of calcination and rehydration (Vrancken and Laethem, 2000). Camarini et al (2015) found that the energy consumption of gypsum plaster waste recycling was similar to natural gypsum calcination done in diesel kilns. The energy consumption during calcination at 150 °C for 1 hour is 447,120 kcal/t and in vertical Kettle was 439,450 kcal/t, which show the energy efficiency of the recycling process.

The practice of recycling or reusing GPW is a feasible alternative that contributes to human and environmental health (Chandara et al., 2009). In Brazil, a proper regulation modified the GPW category and defined these materials as recyclable for other destinations. Thus, they cannot be dumped in landfills (CONAMA, 2011) and recycling is a mandatory issue in the