A gypsum-based construction material can include gypsum core including a stucco component, a siloxane component at a content of not greater than about 2.0 wt. % relative to a content of the stucco component, and a calcium hydroxide catalyst at a content of at least about 0.01 wt. % and not greater than about 0.1 wt. % relative to the content of the stucco component. The gypsum-based construction material can have a pH of at least about 7.5 and not greater than about 10.

According to the present invention, there is provided a wet accelerator for use in the manufacture of a gypsum product, said wet accelerator comprising water, particles of calcium sulphate dihydrate and a stabiliser. Additionally, a method of preparing a wet accelerator and a method of producing a gypsum product are described.

Disclosed is a composite gypsum board comprising a set gypsum core disposed between face (e.g., Manila) and back (e.g., Newsline) cover sheets. The set gypsum core is formed from a core slurry comprising stucco, water, and optional additives, such as foaming agent, migrating starch, accelerator, retarder, dispersant, etc. A dense layer formed from a dense layer slurry comprising stucco, water, fiber (e.g., paper fiber), and optionally, strength-enhancing starch, is disposed between the core and the face paper. The dense layer slurry contains a greater concentration of fiber, and optionally, strength-enhancing starch, than the core slurry, but the concentration of one or more other additives (e.g., accelerator, retarder, dispersant, or combinations thereof) is lower or the same in the dense slurry as compared with the core slurry. Also disclosed is a method of making board using one board mixer. In embodiments, paper fiber is added to water to form a suspension. The suspension is introduced, while in a non-laminar state, into the dense slurry. Further disclosed is apparatus, such as an extractor and an additive injection system, which can be a part of a cementitious slurry mixing and dispensing assembly.

The present disclosure belongs to the technical field of preparation of functional materials, and in particular relates to a grinding aid for cement and a preparation method therefor. The components of the grinding aid include a modified alcohol amine of a specific structure and a polycarboxylic acid polymer of a specific structure, and a mass ratio of the modified alcohol amine to the polycarboxylic acid polymer is (1-10):(40-49), and the early strength of the cement can be increased, the water consumption can be reduced, and the fluidity can be improved when the grinding aid is used in cement. The present disclosure adopts the combined action of the modified alcohol amine and the polycarboxylic acid polymer in specific ratios and structures, so that a synergistic effect can be achieved, and the respective performance advantages can be fully exerted.