Expansion of gypsum stone in the presence of a polycarboxylate hyper plasticizer

Expansion of gypsum rock caused by Melflux 6681F, polycarboxylate hyper plasticizer of the latest generation, was investigated. It was established that the introduction of this additive into gypsum stone at a dosage of 0.35-0.70% by wt of gypsum leads to a linear expansion of the stone within 0.7-8% and its softening. It was also established that this hyper plasticizer affects the shape and size of the crystals of calcium sulfate dihydrate formed from solutions supersaturated with CaSO₄ · 2H₂O. The reason for expansion of the hardening rock, apparently, is the internal pressure developing in the initially formed finely crystalline structure (crystallization pressure) during the subsequent slow recrystallization of gypsum

Author: A.S. Panfilov, I.N. Medvedeva, A.S. Brykov, M.E. Voronkov

Section: Science and production

Keywords: gypsum, polycarboxylate plasticizer, expansion, crystallization pressure