Water-resistant gypsum binder

The authors developed a multi-component gypsum binder (MGB) with an improved (by 1.8 to 2.2 times) water resistance value in comparison with the initial gypsum and a softening factor value within the range of 0.85 to 0.91 through the introduction of a complex additive containing carbide mud and bio-silica. The use of a complex additive provides for the formation of a denser structure due to the formation of low-base calcium hydrated silicates at early stages of the hardening process under wet or dry air conditions. The developed binding agent has a lower (by 2.5 to 3 times) open porosity, a greater compressive strength (by 1.4 to 1.6 times for a dry state and by 2.6 times in a water-saturated state) and does not require any special curing conditions in contrast to the other multi-component gypsum binders. The authors show the influence of mud-and-silica additive on the properties of hardened MGB and suggest a method of computation of the optimum MGB composition for given components