Engineering construction gypsum, also known as hydrated gypsum, is one of the three major admixtures (concrete, lime powder, gypsum) and is a commonly used building decoration material in construction projects. It is produced from pure natural gypsum or industrial by-product gypsum through water shortage, and β Half hydrated gypsum is a basic component of air hardening admixture, and its half hydrated calcium bicarbonate content (mass concentration) should not be less than 85.0%. Mainly used in the production of gypsum engineering construction products.