Analysis of the influence of type, amount and way of introduction of anti-foaming admixture (AFA) on the properties of self-compacting concrete mix

The properties of the self-compacting concrete mix depend on an automatic introduction of air bubbles caught during the process of mixing. What is interesting, the criterion for self-compactibility is not taken into consideration in commonly used self-compacting tests. On the basis of different tests concerning selfcompacting concrete mixes, it has been found out that too high air content in their volume was the result of superplasticizer, in spite of meeting the self-compactibility criteria. For the decrease of too high air volume in SCC, the use of anti-foaming admixture (AFA) is proposed. As a result, the effect of AFA mix flow diameter is increased and the flow time is decreased. Moreover, the workability loss is lower. In case of mix incorporating AFA, their high flowability does not cause segregation of the mix, what is possible in case of SCC incorporating only superplasticizer. However, the time of the introduction of AFA and its type is essential to get higher flowability degree, but is not important to achieve low air volume in SCC.