Papyrus Press Advance Researches in Civil Engineering 2645-7229 6 2 2024 06 01 Schmidt Hammer Test for Estimating Concrete Strength; Calibration and Calibration 13 26 224605 10.30469/arce.2025.504865.1083 EN Sasan Motaghed Assistant Prof., Faculty of Engineering, Behbahan Khatam Alanbia University of Technology, Behbahan, Iran Mohammad Hossein Shabaneh BSc. Special Concrete Center (SCC), Behbahan Khatam Alanbia University of Technology, Behbahan, Iran Mehran Ghasemi Golsorkhdan BSc. Special Concrete Center (SCC), Behbahan Khatam Alanbia University of Technology, Behbahan, Iran Mehdi Mohammadi MSc. Special Concrete Center (SCC), Behbahan Khatam Alanbia University of Technology, Behbahan, Iran Journal Article 2025 02 05 The Schmidt hammer test, a widely recognized non-destructive testing method, is a crucial tool for estimating the compressive strength of existing concrete. This paper addresses the calibration of the Schmidt hammer, emphasizing its importance in ensuring accurate and reliable rebound measurements that correlate with concrete strength. The study highlights the multifaceted challenges associated with the rebound hammer test, including the influence of environmental conditions, surface characteristics, and material composition on test outcomes. Through a systematic approach, we explore the calibration process, detailing methodologies that ensure the device's accuracy and consistency. Experimental results from 29 concrete mix designs demonstrate significant relationships between material proportions and mechanical performance indicators. The findings reveal that optimal combinations of cement, fly ash, and water-cement ratios can enhance concrete strength while maintaining workability. Furthermore, we compare various predictive models for estimating concrete strength based on Schmidt hammer results and jack test measurements. The analysis indicates that power and quadratic models outperform linear models in prediction accuracy, underscoring the necessity for tailored calibration approaches to account for variability in concrete properties. This research not only contributes to refining Schmidt hammer testing protocols but also emphasizes the need for ongoing investigations to enhance non-destructive testing methods in structural assessments. https://www.arce.ir/article_224605_1e5b3fecdc82b15dbf36e1872fabd1b4.pdf