An international team of researchers developed a production method to create high-quality gypsum binders from industrial waste. The new binders are made of synthetic calcium sulfate dihydrate produced from industrial waste and meet the requirements for materials of this class.

Gypsum binders are widely used in construction thanks to their low weight, low heat and sound conductivity, low cost and fire resistance. These binders also are easy to shape, are hypoallergenic and do not cause silicosis, an occupational disease.Natural gypsum stone Source:  Maksim SafaniukNatural gypsum stone Source: Maksim Safaniuk

The team's new method produces high-strength binders based on synthetic gypsum. This material is gathered from industrial waste by neutralizing spent sulfuric acid and carbonate components. Sulfuric acid from waste heat-resistant fibers is mixed with water and limestone; 95% of the final product mass of the synthetic gypsum is made of calcium sulfate dihydrate.

While testing the new material, the team gathered three types of synthetic gypsum samples; building gypsum, high-strength gypsum and anhydrite. The building gypsum was made with traditional tech in the gypsum boiler. The anhydrate was made with traditional tech with firing followed by cooling. Finally, the high-strength gypsum was made with an autoclave. In all situations, the resulting waste-based gypsum was just as strong and useful as the new gypsum.

One advantage to the new material is that synthetic gypsum is produced in a powdered form. In traditional production, gypsum has to be crushed to the right state, using a significant amount of electricity. The new method significantly reduces production costs by simplifying the production tech.

Synthetic gypsum could completely replace natural gypsum binders. This is especially important for countries that do not have gypsum stone deposits.

A paper on the new material was published in the Journal of Industrial and Engineering Chemistry.