MODIFYING ADDITIVE Russian patent published in 2009 - IPC C04B7/00 C04B28/00 C04B111/20 

FIELD: chemistry.

SUBSTANCE: invention relates to construction materials, particularly additives to cement, concrete mixture, mortar, used for making concrete and reinforced concrete objects, as well as gypsum based objects. The modifying additive, a product of processing wastes from sulphuric acid mineral raw material from the Dalnegorsk deposit datolite - wollastonite skarn with storage period of over one month has the following composition, wt %: gypsum dihydrate 61 to 76, amorphous silica 16 to 22, non-decomposed mineral 4 to 12, boric acid 1 to 2, preferably after heating to 100 to 120°C before conversion of dihydrate gypsum to hemihydrate gypsum.

EFFECT: increased strength of construction materials and objects.

5 ex, 1 tbl