The object of research is to investigate the mechanical properties of concrete incorporating carbon black as a novel filler material, with a focus on compressive and tensile strength—a topic previously underexplored in literature. Method. Carbon black, a hydrocarbon-derived soot (Type 660N), was added at 2%, 4%, 8%, and 12% by weight of cement, with water-cement ratios (W/C) of 0.40, 0.45, and 0.5. A total of 150 samples were tested at 7 and 28 days using ASTM-standardized methods, including the Brazilian tensile test. Result. Outcomes demonstrated that 4% carbon black optimally enhanced tensile strength (up to 24.3% increase at W/C=0.40 and 35.9% at W/C=0.45), while higher percentages (8–12%) degraded performance due to pore-filling inefficiencies. Compressive strength followed a similar trend, peaking at 4% replacement. The study highlights carbon black’s potential to improve concrete durability, reduce cement consumption, and mitigate environmental impacts, proposing an optimal dosage for industrial applications.

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