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Microstructure and Mechanical Properties of Sustainable Concrete Incorporating Used Foundry Sand and Coal Bottom Ash

Year: 2025

Type: article

Abstract: This study investigates the potential for sustainable concrete production using industrial by-products: used foundry sand (UFS) and coal bottom ash (CBA). These materials were partially substituted for natural aggregates to reduce environmental impact and promote circular economy practices. UFS was used as a replacement for fine aggregate, while both fine and coarse CBA were tested as substitutes for sand and gravel, respectively. The materials were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) to evaluate their mineralogical and microstructural properties. Six concrete mixtures were prepared with varying replacement levels (up to 70% total aggregate substitution) at a constant water-to-cement ratio of 0.50. Compressive strength tests were conducted at 28 days, supported by microstructural observations. Results showed that high levels of UFS and CBA led to reduced strength, mainly due to weak interfacial bonding and porous ash particles. However, moderate replacement levels (e.g., 20% fine CBA) maintained high strength with good structural integrity. The study concludes that both UFS and CBA can be used effectively in concrete when carefully dosed. The findings support the use of industrial waste in construction, provided that material properties are well understood and replacement levels are optimized.

Source: Sustainability

DOI: 10.3390/su17135983

Author: Piotr Smarzewski

Institution: Military University of Technology in Warsaw

Language: English

Topic: Materials Engineering and Processing

Subfield: Mechanical Engineering

Field: Engineering

Domain: Physical Sciences

SDGs: Responsible consumption and production, Industry, innovation and infrastructure

Open Access status: gold

Estimated APC paid: $2,896