B. Łaźniewska-Piekarczyk

The Influence of the Type of Anti-Foaming Admixture and Superplasticizer on the Properties of Self-Compacting Mortar and Concrete

Abstract To prevent excessive air entrainment, superplasticizers (SPs) should not only be compatible with cement, but also should not create the air-entraining effect in mortar. In order to counteract excessive air entrainment, anti-foaming admixtures (AFAs) can be used to prevent the formation of air bubbles. This paper investigates the influence of the type, amount and time of introduction of AFAs on air-entrainment, rheological properties and workability loss of self-compacting mortar. The research results prove that AFAs decrease air-content in mortar. Mortar containing an AFA does not undergo segregation, as is the case with mortars of a similar degree of fluidity with no AFA and incorporating an SP only. Moreover, mortar with an AFA keeps initial consistency for longer in comparison to mortar with a SP only. The properties of hardened mortar mixes are also investigated. The research results show that AFAs do not have a significant influence on the compressive strength of mortar mixtures. The compres...

Anti-Foaming Admixture (AFA) and its Influences on the Properties of a Fresh Self-Compacting Concrete Mix

Abstract The properties of a concrete mix should secure the self-elimination of needless air bubbles from its volume. What is interesting, these properties are not taken into consideration in commonly used self-compacting tests. On the basis of different tests concerning self-compacting concrete mixes, it has been discovered that too high air content in their volume was a result of a superplasticiser, in spite of meeting the self-compactibility criteria. To decrease too high air volume in SCC, the use of an anti-foaming admixture (AFA) is proposed by the authors. Because of an AFA introduced into a self-compacting mix, air-content in this mix is decreased, mix flow diameter is increased and flow time is decreased. In case of a mix incorporating an AFA, its high flowability does not cause segregation of the mix, which is possible in case of SCC incorporating only a superplasticiser. However, time of introduction of an AFA is essential to get higher flowability degree, but is not important in achieving low ...

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 self-compacting 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.

Influence of Antifoaming Admixture Type on Several Properties of High-Performance Self-Compacting Concrete

AbstractEN 934-2 “Admixtures for concrete, mortar and grout Concrete admixtures. Definitions, requirements, conformity, marking and labelling” requires that any increase in the air content shall not be more than 2% by volume over that obtained from the reference mix, and most types of superplasticizers (SPs) easily meet this requirement. Some types may even reduce the level of air, and this can result in a less cohesive mix, which may be more prone to bleed and segregation or may leave the mix feeling harsh and difficult to handle. Unfortunately, some types of superplasticizers increase the level of air. Too high a volume of air has been overcome using an antifoaming agent. The influence of new-generation type superplasticizer and antifoaming admixture (AFA) on the air content and workability of high performance self-compacting concrete (HPSCC) is analyzed in this paper. The purpose of this study was to examine the influence of the admixture type on pore size distribution, compressive strength and frost r...

Investigations on the relationship between porosity and strength of admixtures modified high performance self-compacting concrete

AbstractThe influence of a type of new generation: superplasticizer (SP), anti-foaming admixture (AFA) and viscosity modifying admixture (VMA) on the air-content, workability of high performance self-compacting concrete (HPSCC) is analyzed in the paper. The purpose of this study was to examine the influence of type of the admixtures on porosity of HPSCC in the aspect of the compressive strength. The research results indicated that type of admixtures and its combinations result in different strengths of HPSCC, regardless of the total porosity characteristics of HPSCC.