Effect of curing procedure on mechanical properties and pore structure characteristics of three different concrete types

Abstract

This study investigates the influence of curing methods on the mechanical properties and pore structure characteristics of concretes including Sulphate-Resisting Cement (SRC), Ordinary Portland Cement (OPC), and Blast-Furnace Slag Cement (BFSC). Two curing regimes were applied: water immersion (Method I) and controlled humidity (Method II) at 22 °C and 80 % RH, with twice-daily water sprinkled for 7 days. Concrete mixtures with a 0.4 water-to-cement ratio and 400 kg/m³ cement content were assessed in terms of fresh properties, including slump, air content, and unit weight. The hardened properties were evaluated through compressive, flexural, and tensile strength tests, in addition to pulse velocity and dynamic elastic modulus measurements. To examine the impact of curing conditions on porosity, Mercury Intrusion Porosimetry (MIP) was used to quantify cumulative intrusion volume, porosity, pore surface area, and average pore diameter. Unlike previous studies that primarily focus on compressive strength, this research uniquely investigates mechanical performance with pore structure variations induced by curing conditions, filling a critical gap in the existing literature. The findings confirm that Method I significantly improves mechanical properties, particularly for SRC, which achieved the highest compressive strength of 741 kg/cm² at 180 days. OPC exhibited the highest flexural strength (86.0 kg/cm² at 28 days), whereas SRC outperformed in tensile strength under Method I. MIP analysis revealed that water immersion curing reduced the average pore diameter of SRC to 0.0266 μm, resulting in denser concrete, making it ideal for aggressive Sulphate-rich and chloride-laden environments. The study further validates nondestructive testing methods, as pulse velocity and dynamic elastic modulus correlated well with compressive strength results, reinforcing their reliability in assessing concrete quality without destructive testing. Additionally, this research provides a practical comparison between standard curing and field-applicable curing methods, addressing real-world construction constraints where continuous water immersion is often impractical. These findings contribute to global research by offering practical insights into curing efficiency, particularly for Sulphate-resistant and blended cementitious systems. Future research should explore extended durability assessments beyond 180 days, alternative curing techniques, and machine learning-based predictive modeling to enhance curing optimization for high-performance concrete in harsh environmental conditions.