Impact of mixture design and production parameters on the crushing strength of cold-bonded alkali activated aggregates made from iron tailings
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Date
2026
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Abstract
This study explores the production and performance of cold-bonded alkali-activated artificial aggregates (CB- AAA) made from highly crystalline iron tailings, a low-reactivity mining by-product. A factorial experimental design was used to assess the influence of five key parameters on crushing strength: aggregate particle size, alkaline activator molarity, co-activator dosage, curing temperature, and curing time. The resulting aggregates exhibited bulk densities from 824 to 1002 kg/m³ , water absorption between 14.78 % and 25.68 %, and crushing strengths ranging from 0.18 to 3.24 MPa. A second-order polynomial regression model was developed and validated, identifying curing temperature as the most significant factor. To evaluate structural applicability, concrete specimens were prepared with 30 % and 100 % replacement of natural coarse aggregates. Higher- quality CB-AAA mitigated compressive strength losses, with partial replacement mixtures retaining up to 60 % of the reference strength. These results demonstrate the feasibility of using iron tailings in low-carbon construction materials despite the low reactivity of these waste materials, and they offer new insights into the role of mixture design and processing conditions in optimizing the performance of CB-AAA for concrete applications.
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Alkali-activated materials, Iron mine tailings, Factorial experimental design, Concrete