Impact analysis of air-entraining and superplasticizing admixtures on concrete compressive strength

摘要

The commonly used air entraining of concrete mixes to ensure the freeze-resistance of concrete results in a compressive strength reduction. The literature states that the average drop in compressive strength is 5.5% per 1% present in the air mix, however the role of the superplasticizer and its effect on the properties of the concrete mix and the structure play an important role in shaping the drop in strength due to air entraining concrete. Therefore, the aim of the paper is to analyze the impact of the simultaneous action of a superplasticizer and air entraining admixture on compressive strength. The analysis were based on the results of eight series of air-entrained and non-air-entrained concretes with a fixed basic composition and the content of air entraining admixture in air entrained concrete, liquefied with a superplasticizer to consistency classes S1, S2, S3 and S4. The test results showed that as the content of the superplasticizer increases, along with the liquefaction of the concrete mix, the pore content decreases and their structure changes. Consequently, compressive strength in hardened air entrained and non air entrained concrete increases from 1-14%. The air entrained of concrete mixes alone results in a loss of strength in the range of 5-17% and is dependent on the content of the superplasticizer, the consistency of the concrete mix, changes in the pore content, and their structure.