The article presents the results of utilizing modified gypsum board waste from construction and demolition debris, obtained from a real construction site and processed using a developed recycling line for construction gypsum board. The research focused on examining the impact of modification (in terms of grinding fineness) on the resulting properties of dry gypsum mixtures, with replacements in the mixture ranging from 10%, 25%, to 50% by weight for gypsum binder. Parameters such as bulk density, flexural strength, and compressive strength after 7 days from the sample production were monitored. The results indicate that, with appropriate modification, it is possible to efficiently substitute a portion of gypsum binder in dry gypsum mixtures with modified gypsum board recyclate.