Joint influence of mineral and chemical additives on the content of entrained air in mortar mixes.

The content of air entrained in cement-sand mortar mix and the size of air bubbles are determined by the competition between molecules of air-entraining and plasticizing agents during their sorption on grains of cement and mineral additives and at the liquid-air interface. Microsilica and metakaolin, characterized by approximately the same ratio of the number of adsorption centers to the surface area of grains, practically in the same degree enhance the air-entraining activity of air-entraining and plasticizing additives introduced into the mortar mix separately. At the same time, the activity of anionic air-entraining activity decreases if added to the mortar mix together with plasticizing additives. However, if microsilica or metakaolin is present in such a mixture, the decrease in the air-entraining activity is largely compensated by a significant growth in the air-entraining efficiency of the plasticizer, but then larger air bubbles are formed.

Author: Yu.M. Kudla, Ye.A. Mikhailova, M.V. Pulman, A.S. Brykov

Section: Science and production

Keywords: air-entraining additives, microsilica, metakaolin, superplasticizers, competition, entrained air, frost resistance of concrete.