SHVEDOV, A. THE EFFECT OF VARIATIONS OF SODIUM SULFATE IN THE COMPLEX ADDITIVE IN CONCRETE MIXTURES BASED ON SULPHONATED HEAVY RESIN PYROLYSIS ON THE PERSISTENCE OF THE MOBILITY OF CONCRETE MIXES. Вестник Полоцкого государственного университета. Серия F. Строительство. Прикладные науки 2019, 19-22.