Performance Boundaries and Economic Viability of Cow Bone Ash and Metakaolin as Cement Replacements in High-Strength Concrete

Authors: Olutaiwo, A., Kadiri, V.O. And *Adanikin, A.

DOI Info: http://doi.org/10.5281/zenodo.21046673

ABSTRACT

The construction industry's high carbon footprint creates the need for development of sustainable cementitious materials. This study evaluates the performance boundaries and economic feasibility of cow bone ash (CBA) and metakaolin (MK) as partial cement replacements in high-strength concrete for rigid pavement applications. Replacement levels up to 30% were systematically evaluated through comprehensive testing of workability, compressive strength, split tensile strength, and economic viability. Five sets of concrete mixes were prepared, comprising control, 30% CBA, 20% CBA + 10% MK, 10% CBA + 20% MK, and 30% MK. Results revealed critical performance thresholds as CBA demonstrated acceptable behaviour as a bulk filler up to 30% replacement, achieving 75% of control compressive strength at 28 days, while enhancing workability. Metakaolin, however, showed negative effects beyond 10% replacement, with 30% MK reducing compressive strength to 51% of the control and compromising workability. Statistical analysis confirmed significant strength variations among mixtures. Economic assessment revealed substantial cost challenges as MK costs 5.71 times more than cement, and CBA costs 8.66 times more. Despite economic constraints, this study establishes crucial replacement boundaries showing that CBA is viable up to 30% for non-critical applications, while MK must be limited to 5-10% replacement levels. These findings provide essential guidance for optimizing ternary blends and preventing potential construction failures in sustainable concrete technology development.

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