Efficiency of Clay-Burnt Brick Fines as an Internal Curing Agent for Enhancing Mechanical and Durability Properties of High-Strength Concrete

This study explores the efficacy of clay-burnt brick fines (CBBF) as an internal curing (IC) agent for high-strength concrete (HSC), focusing on its impact on mechanical and durability properties. Various parameters were examined, including CBBF grain sizes (4.75 to 2.36 mm, 4.75 mm to 75 μm, and <75 μm), water-to-binder (w/b) ratios (0.28, 0.32, and 0.38), and substitution percentages of fine aggregate by CBBF (up to 16%). Furthermore, the study explored replacing a portion of coarse aggregate with clay-burnt brick chips (4.75 to 12.5 mm) to assess the IC performance with larger-sized IC agent. The specimens were tested for compressive strength, non-steady-state chloride migration coefficient, and permeable pore volume. Additionally, concrete specimens were analyzed using ultrasonic pulse velocity (UPV) and scanning electron microscopy. A CBBF content of 8% in concrete was found to yield the highest compressive strength and UPV, as well as providing the highest resistance to chloride ion penetration, while specimens with 4% CBBF exhibited the lowest permeable pore volume. Additionally, finer CBBF proved to be more effective as an internal curing agent. These findings collectively underscore the promising efficacy of CBBF as an IC agent in enhancing both the mechanical properties and durability of high-strength concrete.