Development of Correlation Curve of The Compressive Strength-Maturity Index

Abstract The maturity method is not commonly practiced in estimating in-place concrete strength in Malaysia. However, knowing the in-place or real-time concrete strength is crucial for making critical decisions, such as removing formwork, scheduling post-tensioning operations, and fast-tracking construction projects like bridge repairs to minimize repair time and reduce facility closures. In this study, the maturity method was utilized in developing the correlation curve of Grade 25 concrete (C25), a typical concrete grade frequently used. The temperature of the cylinders was captured by thermocouples and MONSEC. The temperature of the cylinders was recorded using thermocouples. Temperature data from both devices were found to be accurate and consistent. The Nurse-Saul method, with a datum temperature of 32°F (0°C), was employed to calculate the maturity indices. These data were then used to develop the strength- maturity curves, validated through laboratory tests. The results indicate that the correlation curves accurately predict concrete strength, with minor variations of less than 10%. This demonstrates that the compressive strength-maturity index correlation curve is reliable for predicting concrete strength.