Amirkabir University of Technology AUT Journal of Civil Engineering 2588-2899 10 3 2026 07 01 Evaluation of In-situ Concrete Strength using Maturity-Based Strength Modification Factor (SMF): A Field Study in Various Climatic Conditions 243 254 6078 10.22060/ajce.2026.24163.5924 EN Sasan Motaghed Department of Civil Engineering, Faculty of Civil engineering and architecture, Shahid Chamran University of Ahvaz, Ahvaz, Iran 0000-0001-7062-0457 Amin Mashhadi Behbahan Khatam Alanbia University of Technology Abbas Hosseini Yasouj University Mohammad Sadegh Shahidzadeh Behbahan Khatam Alanbia University of Technology Hadi Sayadpour Yasouj University Journal Article 2025 05 15 Accurate estimation of in-situ concrete compressive strength is vital for structural safety and optimizing construction schedules. However, significant discrepancies often exist between standard laboratory-cured specimens and actual field performance due to varying on-site temperature and curing conditions. This study proposes a practical approach to bridge this gap by employing the maturity method to derive a site-specific strength modification factor (SMF). The proposed method was rigorously validated using extensive data collected from five active construction sites in southern Iran, which encompassed a wide range of concrete mix designs and local climatic conditions. A total of twelve experimental series were conducted, directly comparing the compressive strength development of standard laboratory-cured specimens with companion field-cured samples at 7 and 28 days of age.The results establish a significant and quantifiable correlation between the calculated SMF and the ambient curing temperature. Specifically, the SMF at 7 days averaged 1.30 during colder seasons, indicating lower early strength in the field, and 0.86 during warmer seasons. By applying this temperature-dependent SMF to standard laboratory results, the mean prediction error for in-situ strength was substantially reduced from approximately 14% to less than 4%. These findings demonstrate that the SMF approach provides a reliable, quantitatively robust framework for adjusting controlled laboratory data to accurately reflect real-world curing environments. Consequently, this method offers a powerful tool for enhancing on-site quality control protocols and enabling safer, more efficient, and data-driven decisions regarding formwork removal and subsequent construction activities. https://ajce.aut.ac.ir/article_6078_5f8a7deb15235a128fcd99ad6bfde11e.pdf