| Title: | Effect of alkali-activation pre-treatment of sintered aggregates from biomass fly ash on microstructural and mineralogical evolution |
|---|
| Authors: | ID Tesovnik, Anže (Author)
ID Ducman, Vilma (Corresponding author) |
|---|
| Files: |  URL - Source file, visit https://www.sciencedirect.com/science/article/pii/S0272884226010709
URL - Research data, visit http://hdl.handle.net/20.500.12556/DiRROS-24254
 PDF - Presentation file, download (8,71 MB)
MD5: 55B775D115F6AEC2F1E4EA5132674BF0
|
|---|
| Language: | English |
|---|
| Typology: | 1.01 - Original Scientific Article |
|---|
| Organization: |  ZAG - Slovenian National Building and Civil Engineering Institute
|
|---|
| Abstract: | The increasing demand for lightweight construction materials and the depletion of natural aggregates highlight the need for circular solutions based on industrial residues. Co-incineration biomass ash (BA), despite its high availability, carbon content, and variable composition, remains underutilised in high-value applications. This study explores a previously unexamined valorisation route through the production of sintered alkali-activated aggregates using sodium-silicate-assisted pre-treatment. Two BA mixes with different Na2O dosages (7.57 and 5.44 wt% Na2O) were pelletized and thermally treated between 700 and 1200 ◦C. The alkali activation pretreatment simultaneously improved the granulation efficiency, enabled the formation of alkali-activated gel, and supplied Na2O as a flux, significantly influencing the crystalization, melting, and sintering behavior. Comprehensive characterisation using mercury intrusion porosimetry, dilatometry, X-ray diffraction, Fouriertransform infrared spectroscopy, thermogravimetry–differential thermal analysis, and scanning electron microscopy revealed a coherent thermal sequence: from gel deterioration and a macroporosity development below 800 ◦C, to the crystallization of Ca–Mg silicates and the formation of an akermanite-dominated matrix at 800–1000 ◦C, followed by partial melting and sintering in the presence of a liquid phase above 1000 ◦C. A higher alkali content promoted earlier densification and strength development. Aggregates with higher Na2O content (BA1) exhibited an earlier onset and higher intensity of sintering shrinkage, reaching a compressive strength of 4.53 MPa at 1100 ◦C, corresponding to more than a fourfold increase compared to thermally untreated aggregates, whereas the lower-alkali mix (BA2) remained below 0.26 MPa at the same temperature. Open porosity of BA1 aggregates increased to 78.8% after heating to 800 ◦C due to deterioration of the alkali-activated gel, followed by densification accompanied by akermanite-dominated crystallization and pore coalescence, resulting in 73.1% porosity and a bulk density of 1.28 g/cm3 at 1100 ◦C. The results identify BA as a promising precursor for lightweight or dense SAA and demonstrate alkali-activation-assisted thermal treatment to be a technically applicable circular-economy pathway for converting co-incineration BA into value-added construction materials. |
|---|
| Keywords: | alkali-activated materials, biomass ash, sintered aggregates, lightweight aggregates |
|---|
| Publication status: | Published |
|---|
| Publication version: | Version of Record |
|---|
| Publication date: | 04.03.2026 |
|---|
| Publisher: | Elsevier |
|---|
| Year of publishing: | 2026 |
|---|
| Number of pages: | str. 19392-19407 |
|---|
| Numbering: | issue 12, part B |
|---|
| PID: | 20.500.12556/DiRROS-29286  |
|---|
| UDC: | 54 |
|---|
| ISSN on article: | 1873-3956 |
|---|
| DOI: | 10.1016/j.ceramint.2026.03.041 |
|---|
| COBISS.SI-ID: | 271010307 |
|---|
| Copyright: | © 2026 The Authors |
|---|
| Note: |
|
|---|
| Publication date in DiRROS: | 06.05.2026 |
|---|
| Views: | 47 |
|---|
| Downloads: | 41 |
|---|
| Metadata: |    |
|---|
|
:
|
Copy citation |
|---|
| | | | Share: |  |
|---|
Hover the mouse pointer over a document title to show the abstract or click
on the title to get all document metadata. |
