DRY MIXTURES

[:ru]Шнайдер С.[:en]Schneider S.[:] [:ru]«Кнауф Гипс КГ», ФРГ[:en]«Knauf Gips KG», Germany[:]

[:ru]Фёртнер С.[:en]Förthner S.[:] [:ru]«Кнауф Гипс КГ», ФРГ[:en]«Knauf Gips KG», Germany[:]

Alitinform №1 (13) 2010 г. 94-98 p.

Abstract

Additives have a significant influence on the rehydration of calcium sulphate hemihydrate. They often change the crystal habit of growing dihydrate. The changed morphology leads to a different stability in the microstructure of set gypsum. Dynamic-mechanical analyses allow measuring these differences.

Introduction
In the gypsum industry, the setting of stucco is controlled by different additives, for example retarding or accelerating agents. Their influence on the setting process includes changes in the habits of the dihydrate crystals [1]. The morphology of the growing crystals effects the macroscopic behaviour of the final product.

In the following, a method is presented which makes it possible to quantify and follow the developing structure in setting slurries. Additionally, the method shows the influence of the crystal habit on the crystal assembly. At the same time the dihydrate morphology is extensively changed by an amino acid.