DRY MIXTURES

[:ru]Дель Кастильо, П. Д.[:en]Del Castillo, P. D.[:] [:ru]управляющий отделом маркетинга и развития, компания TolsaGroup, Мадрид, Испания[:en]marketing & product development, industrial products group manager, Tolsa Group , Madrid, Spain[:]

Alitinform №6 (27) 2012 г. 90-97 p.

Abstract

The use of mineral rheological additives for the mortar and gypsum industry was initiated during the last decade of the XX century and extended in the beginning of this century. In particular, some minerals belonging to the mineralogical group of Phyllosilicates like sepiolite, attapulgite (palygorskite) and smectites are used for modifying the rheological properties of cement and gypsum systems. This family of phyllosilicates is also known as “Special Clays” due to their rheological and absorbing properties. With the extended use of thin set mortars and high performance mortars, the kind of additives that are used in the industry have introduced a variety of different challenges that have been solved with the involvement of natural products based on these special clays.
The main uses of special clays in mortars are based on their shear thinning (pseudoplastic) and thixotropic behaviour with cement and gypsum pastes. In particular, these properties improve the flow of these systems using cellulose ethers as thickeners and water retention agents, and redispersable powders. This is transformed into clear benefits on workability, sag and sliding control, surface finishing and removal of sedimentation of aggregates and bleeding.

Key words:

special clays; sepiolite; attapulgite; adherence; cellulose derivative