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

Abstract

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. HSC is widely utilized in various civil engineering projects, including high-rise buildings, bridges, industrial facilities with heavy machinery, and prestressed concrete structures. HSC is also essential for enhancing the long-term durability of concrete structures. To address some of the key challenges associated with HSC, CBBF can be employed as an IC agent. CBBF improves both the mechanical properties and durability of HSC, making it particularly effective for high-rise buildings, bridges, and coastal structures where resistance to chloride ion penetration is crucial. CBBF also contributes to sustainable construction by repurposing waste materials, offering a cost-effective alternative to conventional internal curing agents. It also improves the microstructure of concrete and reduces permeability, which is particularly beneficial in water-retaining structures, dams, and foundations. Overall, CBBF provides a sustainable, durable, and high-performance solution for modern construction projects.