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Vol.26, No.2, 2026, pp. 255–261 |
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NON-DESTRUCTIVE ESTIMATION OF COMPRESSIVE STRENGTH OF LONG-TERM AGED CONCRETE BASED ON DYNAMIC ELASTIC MODULUS Marko Stojanović1 Aleksandar R. Savić3 1) Institute for Testing of Materials-IMS, Belgrade, SERBIA M. Stojanović https://orcid.org/0000-0003-1804-5138 ; M. Vasić https://orcid.org/0000-0002-5743-6038 ; A. Terzić https://orcid.org/0000-0002-4762-7404 ; K. Janković https://orcid.org/0000-0003-3744-3799 2) Academy of Technical and Art Applied Studies, Belgrade, SERBIA F. Pantelić https://orcid.org/0000-0003-4653-9901 3) University of Belgrade, Faculty of Civil Engineering, Belgrade, SERBIA A.R. Savić https://orcid.org/0000-0002-1777-6775 4) Innovation Centre of the Faculty of Mechanical Engineering, Belgrade, SERBIA S. Sedmak https://orcid.org/0000-0002-2674-541X *email: milos.vasic@institutims.rs
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Abstract This study investigates the applicability of non-destructive testing for estimating the compressive strength of concrete after long-term aging. Three concrete mixtures are analysed: reference concrete, air-entrained concrete, and rubberised concrete, all produced with a constant water-cement ratio of 0.40. Compressive strength is experimentally determined at 3, 7, 28, and 90 days, while the dynamic elastic modulus is obtained after approximately 803 days using a resonance-based non-destructive method. The long-term compressive strength is then estimated from the measured modulus using an established modulus-strength relationship. In addition, bulk density and air-void system parameters are analysed to support the interpretation of results. The air-entrained concrete exhibits a developed system of fine and uniformly distributed air voids, while the rubberised mixture contains a deformable low-density phase due to the presence of rubber particles. The results indicate that the modulus-based estimation provides physically consistent trends; however, its accuracy depends on the internal structure of concrete. The reference concrete shows an increase in estimated strength after long-term aging, while the air-entrained and rubberised mixtures exhibit deviations related to their modified pore structure and phase composition. The study demonstrates that non-destructive evaluation based on dynamic elastic modulus can be applied for long-term strength assessment, but calibration of the modulus-strength relationship is necessary for different types of concrete. Keywords: • non-destructive testing • static and dynamic modulus • compressive strength • air-entrained concrete • rubberised concrete |
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