Mine tailings, the residual waste from mining operations, could provide an innovative solution to sustainable concrete production, particularly through their incorporation in ultra-high-performance fiber-reinforced concrete (UHPFRC). Recent research highlights the potential for utilizing mine tailings powder (MTP) and mine tailings sand (MTS) as substitutes for conventional cement and aggregates, allowing for reductions in both environmental impact and resource depletion.
Conventional concrete production is energy-intensive and produces significant carbon dioxide emissions, contributing to climate change. UHPFRC, known for its exceptional mechanical properties, often relies heavily on Ordinary Portland Cement (OPC), which necessitates the exploration of alternative materials. To tackle this challenge, the research investigates how varying proportions of MTP and MTS affect the workability, strength, and durability of UHPFRC.
This study, drawing upon laboratory analyses, indicates notable advantages when incorporating mine tailings. For example, the optimal mix demonstrates remarkable improvements; including 15% MTP and 60% MTS enhanced the compressive strength of UHPFRC by 12.49%, achieving strength values of 165.2 MPa after 90 days. The enhancements not only indicate performance benefits but also position mine tailings as sustainable materials compatible with high-performance construction practices.
According to the authors of the article, “The results indicate the optimal mix of 15% MTP and 60% MTS enhances compressive strength and significantly improves sulfate resistance.” This finding emphasizes the utility of these industrial by-products, which could mitigate the environmental burdens associated with cement production.
The significance of this research lies within the dual role of mine tailings. MTP contributes pozzolanic properties, reacting with calcium hydroxide during hydration, whereas MTS improves the granular structure of concrete. Collectively, these characteristics lead to reduced permeability and improved durability of concrete exposed to harsh environments.
Aside from strength benefits, the study also assesses other mechanical properties. Results reveal increases of 23.53% and 23.04% at 90 days for indirect tensile strength and modulus of rupture, respectively, for the optimal mix. This reflects the improved bonding and strength characteristics conferred by the integrated tailings.
Addressing the environmental impact, the authors note, “The incorporation of mine tailings presents both mechanical benefits and promotes sustainability by recycling industrial waste.” Given the substantial volume of tailings produced annually—estimated at 3 billion tons globally—leverage of these resources for concrete applications can present substantial opportunities for waste reduction.
The study carefully explores the interaction mechanisms between MTP, MTS, cement, and water through advanced analytical techniques such as X-ray diffraction and mercury intrusion porosimetry. These methods reveal the microstructural changes facilitated by the introduction of tailings, indicating enhancements in hydration kinetics and pore structure, which optimize the material's intrinsic properties.
Even though higher proportions of MTP and MTS return diminishing returns past optimal thresholds, the study advises focusing more on dual-material approaches to achieve ideal sustainability without compromising structural integrity.
Moving forward, this research paves the way for more extensive explorations of waste recycling within the construction industry, potentially revolutionizing standard practices to favor environmentally friendly approaches. It highlights the importance of seeking alternatives not just to lower carbon footprints but to create innovative, high-performance building materials from otherwise discarded waste.
Overall, the findings advocate incorporating mine tailings as effective substitutes for cement and aggregates. Utilizing these materials not only enhances UHPFRC’s mechanical performance but also contributes positively toward sustainability efforts, presenting feasible pathways for the construction industry to become more eco-efficient and responsible.