ĐÁNH GIÁ CƯỜNG ĐỘ CỦA BÊ TÔNG KHI SỬ DỤNG PHỤ GIA R7

Abstract

There are various types of early strength-enhancing admixtures for concrete that allow formwork to be removed at 7 days instead of 28 days if no admixtures are used. However, the effectiveness of each type of admixture varies. Therefore, the topic “Evaluation of Concrete Strength When Using R7 Admixtures” aims to compare and assess the effectiveness in terms of compressive strength of using Sikament R7N and Super R7 admixtures under the same conditions at the 7-day mark. The study was conducted on B15 (M200) concrete using admixture dosages as recommended by the manufacturers. Concrete samples were cast and cured according to Vietnamese standards and tested for compressive strength at 7 days. The research results showed that Sikament R7N and Super R7 admixtures significantly accelerated the compressive strength development of concrete within the first 7 days, thereby shortening the formwork removal time and speeding up construction progress. At the recommended dosage, Sikament R7N and Super R7 enabled the concrete to reach 84% and 78% of its design compressive strength at 7 days, respectively. However, this study only focused on the technical aspect by comparing compressive strength and did not address economic efficiency or other factors when using these two types of admixtures. Therefore, further research is needed to comprehensively compare the effectiveness of the two admixtures in order to make the most suitable choice.