Influence of clay minerals on the action of
PCE superplasticizers – description of the phenomenon
and possible solutions
J. Plank, Technical University of Munich, Department of Chemistry,
Clay minerals, which can be contained in aggregates or in limestone meal, reduce the flowability of concretes by absorption (consumption) of water. Superplasticizers also settle on the surfaces of the clay particles and are then no longer available for plasticizing the cement paste. Polycarboxylates in particular can also be incorporated in the chemical structure of the clay mineral montmorillonite (bentonite) and in this way are removed from the cement paste so that their plasticizing action is partially or even entirely lost. The negative effects of clay minerals can be lessened or completely eliminated by using clay-resistant PCE superplasticizers, by supplementary addition of cationic compounds or by “sacrificial substances”.
Summary CEMENT INTERNATIONAL 05/2016 pp 58-61
Order a single issue