US Patent 11584690 Multi-layer gypsum board and related methods and slurries

Disclosed is a composite gypsum board comprising a board core and a concentrated layer, as well as related methods of preparing board and slurries. The board core and the concentrated layer both are formed from water and stucco. The concentrated layer is designed to have higher density and/or nail pull than the core. The concentrated layer is further formed from a polysaccharide that forms a complex with calcium ions, e.g., an alginate compound such as sodium alginate. In some embodiments, the concentrated layer is formed from an enhancing additive to enhance strength therein, while the core is formed without using enhancing additive or less enhancing additive than used in forming the board core.