Author(s): Chiamaka N Okafor

Abstract: The growing demand for environmentally responsible construction practices has intensified interest in recycled aggregate concrete (RAC) as a sustainable alternative to conventional concrete. This study evaluates the mechanical and durability performance of RAC produced with varying replacement levels (0-100%) of recycled concrete aggregates (RCA) in place of natural aggregates. Comprehensive laboratory tests were conducted to examine compressive strength, tensile strength, flexural strength, modulus of elasticity, water absorption, chloride permeability, carbonation depth, drying shrinkage, and freeze-thaw resistance. Statistical analyses, including one-way ANOVA and linear regression, were applied to assess the significance of RCA content on the measured properties and to establish empirical correlations. The results indicate a consistent decline in mechanical properties with increasing RCA replacement, primarily due to the adhered old mortar and higher porosity of RCA. However, mixes with up to 30-50% RCA maintained comparable mechanical strength to conventional concrete, confirming its suitability for general structural applications. Durability properties exhibited greater sensitivity, with increased water absorption and chloride penetration corresponding to reduced resistivity and higher carbonation depth. The incorporation of fly ash as a supplementary cementitious material mitigated these effects, improving overall durability performance. Based on these findings, the study recommends the combined use of optimized mix design, RCA pre-treatment, supplementary materials, and effective curing regimes to achieve performance parity with natural aggregate concrete. The outcomes contribute to developing sustainable construction practices and provide a data-driven foundation for design guidelines and policy formulation supporting the broader adoption of recycled materials in infrastructure development.

Pages: 58-63 | Views: 3 | Downloads: 2

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