Effects of Synthetic Air Entraining Agents on Compressive Strength of Portland Cement Concrete – Mechanism of Interaction and Re

Download Final Report

CAIT project no.: 82 RU901

Fiscal Year: 1998/1999

Status: Final

Rutgers-CAIT Author(s): Patrick J. Szary, Ali Maher

External Author(s): Farhad Ansari, University of Illinois at Chicago, Zhijun Zhang, Nicholas Vitillo



This report details the investigation pertaining to a research program which was undertaken in order to determine the reasons behind the loss of compressive strength in concretes containing synthetic air entraining admixtures. The research program involved four different brands of admixtures, and two different types of admixtures per brand. The four brands are coded brands A, B, C, and D, respectively. A separate key to the brand codes is provided for NJDOT. Brand-C manufactured two different types of Vinsol resins and both were examined in this investigation. For brands B and D two types of mixtures were prepared: (1) those containing water reducing admixtures, and (2) mixtures with high range water reducers. While the primary objective of the research program was to investigate all the admixtures at normally recommended dosages, additional tests were performed for higher dosages for the agents manufactured by brand-D. The experimental program involved determination of compressive strength, measurement of air content at fresh state, detailed determination of air void parameters at the hardened state, and measurement of surface tension of admixtures in water and cement filtrates. The results of research indicated that, concretes produced by the synthetic air entraining admixtures, in general exhibited lower compressive strengths than those produced by Vinsol resin agents. The primary reason for the strength loss associated with the Synthetic air-entraining admixtures was creation of larger air bubbles (voids) by these admixtures. In general, synthetic air entraining admixtures increased the surface-tension-reduction capability of the cementitious mixture, giving rise to the creation of larger bubbles. However, results were brand sensitive and brand B synthetic agent exhibited not much of strength loss with good air void properties. Variable levels of strength loss were observed with other brands. Development of generalized correlation relationships between loss of strength and the use of synthetic agents will lead to erroneous results. It is possible to establish such relationships based on availability of data with information as to the brand, type.