Sustainable Construction: Researchers Explore Waste Foundry Sand as Alternative to Natural Sand

Strategic Insights -

Researchers from the University of Johannesburg have been investigating the potential of waste foundry sand (WFS) as a sustainable alternative to natural sand in the construction industry. Their study, published in the journal Construction Materials, identified WFS as a promising candidate for reducing the depletion of natural sand resources, which have been intensified by the rapid expansion of the construction sector. The researchers evaluated the environmental performance and engineering feasibility of using WFS in construction, categorizing 152 peer-reviewed studies into four thematic areas: material characterization, construction applications, environmental impacts, and regulatory frameworks.

Key Takeaways:

  • The use of waste foundry sand (WFS) as a substitute for natural sand in construction can deliver compressive strength within ±5% of control mixes and reduce water absorption by 5-15% at optimal replacement levels.
  • Substituting 10-30% of natural sand with WFS in concrete and asphalt can achieve these benefits, but contamination risks remain a concern due to chromium and copper concentrations in raw WFS.
  • A six-stage framework is proposed to address contamination risks and ensure responsible reuse of WFS, comprising end-of-waste classification, contaminant assessment, material preprocessing, certification, and regulatory monitoring.
  • A comprehensive decision tree is presented to guide the feasibility assessment of WFS reuse based on contaminant levels and material performance.
  • The study emphasizes the need for a systematic review of WFS use in construction to address environmental and regulatory concerns.

Statistics:

  • 152 peer-reviewed studies published between 2001 and 2024 were evaluated in the study.
  • Contamination risks remain a concern due to chromium and copper concentrations in raw WFS, with levels reported at up to 931 mg/kg and 3318 mg/kg, respectively.
  • Optimal replacement levels of natural sand with WFS range from 10-30%.

Sources:

  • "Foundry Sand in Sustainable Construction: A Systematic Review of Environmental Performance, Contamination Risks, and Regulatory Frameworks" (Construction Materials, 2025, 5(3): 57)
  • University of Johannesburg, Department of Civil Engineering Science, Faculty of Engineering and the Built Environment
  • MDPI AG (publisher of Construction Materials)
  • https://doi.org/10.3390/constrmater5030057 (free version of the journal article)