**Figure 12.**

*Performance of normal and air-entrained concrete exposed to freezing a) cumulative hydraulic pressure oversaturated voids b) mitigating hydraulic overpressure condition by the distribution of air bubbles [38].*

*Concrete Performance in Cold Regions: Understanding Concrete's Resistance… DOI: http://dx.doi.org/10.5772/intechopen.99968*

dosage rate of air-entraining admixtures. Viscosity modifying admixture increases the mix viscosity and its mode of action depends on the type and concentration of the polymer in use, while the superplasticizer causes a reduction in total air void surface areas and increases in air void spacing factors [31, 42]. Meanwhile, polycarboxylate superplasticizers usually have an air-entraining effect, wherewith the use of polycarboxylate superplasticizers; the air voids characterize with smaller diameters than voids formed as a result of lingosulphonicor naphthalene superplasticizers [41, 43].

The usage of admixtures such as viscosity modifying admixtures and superplasticizers can reduce the ability of an air-entraining admixture to create a proper air void system. Where the air content seems to be decreased with the increase of viscosity modifying admixture content and that will probably necessitate greater additions of air-entraining admixture to secure a given air volume [44, 45]. However, and generally; because of the complexity of modern air-entraining admixtures and other chemical admixtures, it is impossible to generalize the effects of their interactions with surfactants on the air entrainment.
