Durability assessment of a highly eco-efficient low-cement Basic Oxygen Furnace slag concrete

Abstract This paper evaluates the performance of a highly eco-efficient low-cement concrete incorporating Basic Oxygen Furnace slag (BOFS) as a raw material. The BOFS was processed to obtain fine and coarse powders, with the mix design based on a modified Andreassen method to enhance particle packing at the paste level. This approach resulted in concretes with a cement consumption of only 86.6 kg·m-3. The BOFS concretes were assessed through water absorption, ultrasonic pulse velocity, forced resonant frequency, modulus of elasticity, compressive strength, tensile strength, and pore system analysis. Additionally, electrical resistivity and accelerated carbonation tests were conducted. At 28 days, the BOFS concrete achieved a compressive strength of 35.1 MPa, corresponding to a cement intensity of 2.47 kg·m-3·MPa−1, with substantial strength gains at later ages. Despite its relatively low electrical resistivity due to the iron content, the BOFS concrete exhibited a dense microstructure (void index of 5.5% and ultrasonic pulse velocity of 4276 m/s) and remained stable under high-temperature water immersion. The optimized particle packing contributed to high mechanical performance and promising durability, as evidenced by the low carbonation depth (less than 10 mm in 120 days under 8% CO2). These findings demonstrate that highly eco-efficient BOFS concrete can achieve durability comparable to conventional Portland cement-based concretes. This study reinforces the potential of BOFS as a sustainable alternative, promoting circular economy practices and reducing the environmental footprint of the construction industry.