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Abstract: With the trend towards renewable alternatives to fossil fuel sources, further uses of biomass and waste ash instead of landfilling are being explored. This study investigates the potential of fly and bottom ashes from burning wood (alone or with coal), as well as coal-co-combustion of municipal solid waste, sewage sludge, and paper sludge, for use in extruded fired bricks fired at 950 °C. The influence of ash content (0 to 15 wt% ash) and ash type (10 wt% ash) on the physical, mechanical, and microstructural properties of the fired bricks was studied. The compressive strength of the reference sample without ash was 72.6 MPa and decreased gradually with an increasing ash content. Open porosity ranged from 28% (reference, no ash) to 43% (15 wt% ash), and water absorption from 12% to 28%, reflecting the pore-forming role of the added ashes. All samples had a compressive strength above the 10 MPa limit specified in EN 772-1, except for bricks with 5 wt% paper sludge bottom ash (B4, W-PS BA). The leaching concentrations indicate that heavy metals were effectively immobilised within the ceramic structure of the fired bricks, relative to inert and non-hazardous waste limit values under EN 12457-2 test conditions. These results suggest that 5% substitution of primary raw materials with ashes may contribute to the production of bricks with reduced environmental impact and improved resource efficiency. The study provides a basis for further formulation of extruded bricks with biomass and waste-derived ashes.
Keywords: biomass and waste derived ashes, clay, extruded fired bricks, ceramic-technological tests, microstructure, leaching
Published in DiRROS: 15.06.2026; Views: 138; Downloads: 231
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Abstract: The gradual replacement of coal by local renewable resources leads to an increased production of co-combustion ashes (CC). Their disposal can be limited by their use in the construction sector, where they can partially replace primary raw materials. This study evaluates the incorporation of selected Slovenian CC ash into clay-based fired bricks within the EU AshCycle project. The tests included the measurement of water absorption, porosity, density, weight loss, shrinkage, flexural and compressive strength, and freeze-thaw resistance. Two types of clay were used to compare the influence of the selected ash on the performance of the fired samples. Replacing clay mixtures with 10 wt% CC ash reduced the compressive strength of the fired bricks but it still reached the required 10 MPa as specified in EN 772-1 (2015). The addition of CC ash to fired bricks requires careful planning of the raw mixes, taking into account various parameters that may affect the properties of the products.
Keywords: fired clay bricks, waste ashes, raw mixture, ceramic-technological tests, freeze-thaw resistance
Published in DiRROS: 07.04.2025; Views: 1136; Downloads: 750
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Abstract: The dataset supports the data in the tables and figures in the conference article Evaluation of the performance of clay-based bricks with the addition of co-combustion ash (doi: https://doi.org/10.18690/um.fkkt.1.2025.15). It contains the particle size distribution (PSD) measurements, the original data of the XRD analyses, the original results of the XRF measurements, the original results of the water absorption and shrinkage of the samples, fired in gradient kiln as well as the original results of the ceramic-technological tests of bricks after drying and firing at 950 °C.
Keywords: fired clay bricks, waste ashes, raw mixture, ceramic-technological tests, freeze-thaw resistance
Published in DiRROS: 03.12.2024; Views: 1328; Downloads: 713
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Abstract: The EU prioritizes transitioning to a circular economy, aiming to boost sustainable resource management through policies promoting recycling and reuse, benefiting both the environment and the economy. Many successful case studies demonstrate using various incineration waste by-products (ashes) as substitutes for natural materials, yielding environmental advantages and showcasing sustainable resource management practices. While extensive literature covers ash characterization and applications, the direct links between the properties of the main components, the amorphous phase, and research findings remain elusive. Analysis predominantly centers on microstructural phase development, influencing mechanical, physical, and chemical properties and guiding research interpretations. Existing standards for ash use primarily address coal-derived fly ash, with SIST EN 13282-2 allowing alternative sources like circulating fluidized bed and paper sludge incineration residues. Yet, beyond this standard, no regulations mandate using different ash types. Nonetheless, the applicability of ashes for the geotechnical composite materials has already been confirmed in the field since numerous geotechnical projects have been carried out in Slovenia. Such composites have been recognized as beneficial practices, and the majority of them also possess legal permission for usage according to the Slovenian Technical Approvals. Given the varying value and complexity of ashes, detailed characterization before use is crucial. Assessing the recycling potential of different ashes requires a precise definition of basic properties such as microstructure, minerals, and chemical composition. Emphasis should be placed on characterizing the hydraulic properties and gaining detailed insights into the amorphous phase, ensuring informed decision-making regarding their recycling processes.
Keywords: waste by-products from incineration processes, ashes, recycling, amorphous phase, (latent) hydraulic properties, hydration
Published in DiRROS: 22.07.2024; Views: 1231; Downloads: 920
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