Pozzolanic Reactivity of Calcareous Low-Grade Calcined Clays

Öz

Clays have played a fundamental role in human development, from early use in pottery and construction to modern applications in advanced ceramics, pharmaceuticals and environmental remediation. Their properties, combined with their abundance, make them an indispensable material for meeting today's engineering challenges, reinforcing their importance for sustainable development and technological innovation. With the increasing urgency of carbon emission reduction, the use of calcined clays to reduce the carbon footprint of the cement sector has become a near-term focus. It is well known that heating kaolinitic clays to certain temperatures increases their reactivity, making them suitable for cement and concrete applications, such as the use of metakaolin in high performance concrete and limestone calcined clay cements for reduced carbon intensity. Of particular interest, however, is the calcination of under-utilized low-grade clays that are not used in such production processes and do not meet the stringent requirements of high-quality ceramics, paper coatings or refractories. When properly processed, these low-grade clays may also exhibit pozzolanic reactivity, enhancing the durability and performance of cementitious systems while simultaneously reducing environmental impact and offering economic advantages. This study evaluated the pozzolanic reactivity of eight different clays, actively employed and readily sourced by Turkish cement plants from their existing deposits, following thermal activation at 600°C and 800°C. The relationship between the presence of kaolinite, montmorillonite, illite, and calcite, and the resulting pozzolanic reactivity was analyzed. Thermogravimetric analysis/differential thermal analysis (TGA/DTA), X-ray diffraction (XRD), X-ray fluorescence (XRF), and particle size distribution (PSD) analyses were performed on the clays for characterization. The results showed that samples with higher clay mineral content exhibited lower strength in the absence of calcite. In other words, it was ultimately demonstrated that even clays with lower clay mineral content can be effectively utilized as SCMs through thermal activation, with the presence of calcite further enhancing their reactivity.

Anahtar Kelimeler

• Clay calcination
• clay composition
• calcareous clays
• strength activity index
• sustainable cement production

Kaynakça

1. T. S. Ledley, E. T. Sundquist, S. E. Schwartz, D. K. Hall, J. D. Fellows, and T. L. Killeen, “Climate change and greenhouse gases,” Eos, Transactions American Geophysical Union, vol. 80, no. 39, pp. 453–458, Sep. 1999, doi: 10.1029/99EO00325.
2. Framework Convention on Climate Change, “Report of the Conference of the Parties on its twenty-first session,” Paris, Jan. 2016.
3. F. Pacheco Torgal, S. Miraldo, J. A. Labrincha, and J. De Brito, “An overview on concrete carbonation in the context of eco-efficient construction: Evaluation, use of SCMs and/or RAC,” Constr Build Mater, vol. 36, pp. 141–150, Nov. 2012, doi: 10.1016/J.CONBUILDMAT.2012.04.066.
4. R. Feiz, J. Ammenberg, L. Baas, M. Eklund, A. Helgstrand, and R. Marshall, “Improving the CO2 performance of cement, part I: utilizing life-cycle assessment and key performance indicators to assess development within the cement industry,” J Clean Prod, vol. 98, pp. 272–281, Jul. 2015, doi: 10.1016/J.JCLEPRO.2014.01.083.
5. J. Duchesne, “Alternative supplementary cementitious materials for sustainable concrete structures: a review on characterization and properties,” Waste Biomass Valorization, vol. 12, no. 3, pp. 1219–1236, Mar. 2021, doi: 10.1007/s12649-020-01068-4.
6. M. Tokyay, “Cement and concrete mineral admixtures,” Cement and Concrete Mineral Admixtures, pp. 1–305, Apr. 2016, doi: 10.1201/B20093/CEMENT-CONCRETE-MINERAL-ADMIXTURES-MUSTAFA-TOKYAY/RIGHTS-AND-PERMISSIONS.
7. S. Prakasan, S. Palaniappan, and R. Gettu, “Study of Energy Use and CO2 Emissions in the Manufacturing of Clinker and Cement,” Journal of The Institution of Engineers (India): Series A, vol. 101, no. 1, pp. 221–232, Mar. 2020, doi: 10.1007/S40030-019-00409-4.
8. F. Eren, M. Keskinateş, B. Felekoğlu, and K. Tosun Felekoğlu, “Mineral Katkı İkamesinin Kalsiyum Alümina Çimentolu Harçların Taze Hal ve Zamana Bağlı Sertleşmiş Hal Özelliklerine Etkileri,” Turkish Journal of Civil Engineering, vol. 34, no. 3, pp. 139–162, May 2023, doi: 10.18400/TJCE.1288033.

9. S. Çelik, S. B. İkizler, D. Aqra, and Z. Angin, “Using Sea Shell, Lime and Zeolite as Additives in the Stabilization of Expansive Soils,” Turkish Journal of Civil Engineering, vol. 36, no. 3, pp. 21–37, May 2025, doi: 10.18400/TJCE.1464572.
10. F. Massazza, “Pozzolanic cements,” Cem Concr Compos, vol. 15, no. 4, pp. 185–214, Jan. 1993, doi: 10.1016/0958-9465(93)90023-3.
11. World Business Council for Sustainable Development, “Cement Industry Energy and CO2 Performance: Getting the Numbers Right (GNR),” 2016.
12. D. D. Eberl, “Clay mineral formation and transformation in rocks and soils,” Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences, no. A311, pp. 241–257, Jun. 1984, doi: 10.1098/RSTA.1984.0026.
13. Y. Tardy, G. Bocquier, H. Paquet, and G. Millot, “Formation of clay from granite and its distribution in relation to climate and topography,” Geoderma, vol. 10, no. 4, pp. 271–284, Dec. 1973, doi: 10.1016/0016-7061(73)90002-5.
14. E. Chiotis, E. Dimou, G. Papadimitriou, and S. Tzoutzopoulos, “The study of some ancient and prehistoric plasters and watertight coatings from Greece,” Archaeometry Issues In Greek Prehistory And Antiquity, 2001.
15. R. Fernandez, F. Martirena, and K. L. Scrivener, “The origin of the pozzolanic activity of calcined clay minerals: A comparison between kaolinite, illite and montmorillonite,” Cem Concr Res, vol. 41, no. 1, pp. 113–122, Jan. 2011, doi: 10.1016/J.CEMCONRES.2010.09.013.
16. A. Tironi, M. A. Trezza, E. F. Irassar, and A. N. Scian, “Thermal Treatment of Kaolin: Effect on the Pozzolanic Activity,” Procedia Materials Science, vol. 1, pp. 343–350, Jan. 2012, doi: 10.1016/J.MSPRO.2012.06.046.
17. Y. A. Atalay, T. Aydin, Z. Başaran Bundur, P. Mokhtari, M. A. Gülgün, and Z. Lafhaj, “Optimization of Hybrid Microwave Curing Approach Based On the Performance of Metakaolin-Based Geopolymer Mortars,” Turkish Journal of Civil Engineering, vol. 35, no. 6, pp. 47–64, Nov. 2024, doi: 10.18400/TJCE.1322047.
18. J. Ambroise, M. Murat, and J. Péra, “Hydration reaction and hardening of calcined clays and related minerals V. Extension of the research and general conclusions,” Cem Concr Res, vol. 15, no. 2, pp. 261–268, Mar. 1985, doi: 10.1016/0008-8846(85)90037-7.
19. O. D. Huang et al., “Feasibility of using calcined clays and reclaimed coal ashes in binary and ternary cementitious systems,” Journal of Building Engineering, vol. 95, p. 110186, 2024, doi: https://doi.org/10.1016/j.jobe.2024.110186.
20. C. He, E. Makovicky, and B. Øsbæck, “Thermal stability and pozzolanic activity of calcined illite,” Appl Clay Sci, vol. 9, no. 5, pp. 337–354, Feb. 1995, doi: 10.1016/0169-1317(94)00033-M.
21. T. Danner, G. Norden, and H. Justnes, “The Effect of Calcite in the Raw Clay on the Pozzolanic Activity of Calcined Illite and Smectite,” in Calcined Clays for Sustainable Concrete, S. Bishnoi, Ed., Singapore: Springer Singapore, 2020, pp. 131–138.
22. B. Lothenbach, K. Scrivener, and R. D. Hooton, “Supplementary cementitious materials,” Cem Concr Res, vol. 41, no. 12, pp. 1244–1256, Dec. 2011, doi: 10.1016/J.CEMCONRES.2010.12.001.
23. M. Atkins, F. P. Glasser, and A. Kindness, “Cement hydrate phase: Solubility at 25°C,” Cem Concr Res, vol. 22, no. 2–3, pp. 241–246, Mar. 1992, doi: 10.1016/0008-8846(92)90062-Z.
24. A. Bahhou, Y. Taha, R. Hakkou, M. Benzaazoua, and A. Tagnit-Hamou, “Assessment of hydration, strength, and microstructure of three different grades of calcined marls derived from phosphate by-products,” Journal of Building Engineering, vol. 84, p. 108640, 2024, doi: https://doi.org/10.1016/j.jobe.2024.108640.
25. A. M. Dunster, J. R. Parsonage, and M. J. K. Thomas, “The pozzolanic reaction of metakaolinite and its effects on Portland cement hydration,” J Mater Sci, vol. 28, no. 5, pp. 1345–1350, Mar. 1993, doi: 10.1007/BF01191976/METRICS.
26. A. Alujas, R. S. Almenares, S. Betancourt, and C. Leyva, “Pozzolanic reactivity of low grade kaolinitic clays: Influence of Mineralogical Composition,” Appl Clay Sci, vol. 108, pp. 94–101, May 2015, doi: 10.1016/J.CLAY.2015.01.028.
27. K. L. Scrivener, V. M. John, and E. M. Gartner, “Eco-efficient cements: Potential economically viable solutions for a low-CO2 cement-based materials industry,” Cem Concr Res, vol. 114, pp. 2–26, Dec. 2018, doi: 10.1016/J.CEMCONRES.2018.03.015.
28. S. Barbhuiya, J. Nepal, and B. B. Das, “Properties, compatibility, environmental benefits and future directions of limestone calcined clay cement (LC3) concrete: A review,” Journal of Building Engineering, vol. 79, p. 107794, Nov. 2023, doi: 10.1016/J.JOBE.2023.107794.
29. X. Huang, Z. Huang, Y. Zhou, R. Hu, and B. Hu, “Life cycle assessment and cost analysis of LC3 concrete considering sustainability and uncertainty,” Journal of Building Engineering, p. 111960, 2025, doi: https://doi.org/10.1016/j.jobe.2025.111960.
30. A. Alujas, R. Fernández, R. Quintana, K. L. Scrivener, and F. Martirena, “Pozzolanic reactivity of low grade kaolinitic clays: Influence of calcination temperature and impact of calcination products on OPC hydration,” Appl Clay Sci, vol. 108, pp. 94–101, May 2015, doi: 10.1016/J.CLAY.2015.01.028.
31. B. Liu, X. Gu, H. Wang, J. Liu, M. L. Nehdi, and Y. Zhang, “Study on the mechanism of early strength strengthening and hydration of LC3 raised by shell powder,” Journal of Building Engineering, vol. 98, p. 111422, 2024, doi: https://doi.org/10.1016/j.jobe.2024.111422.
32. T. A. Østnor and H. Justnes, “Durability of mortar with calcined marl as supplementary cementing material,” Advances in Cement Research, vol. 26, no. 6, pp. 344–352, 2014, doi: 10.1680/adcr.13.00040.
33. Y. Akgün, “Behavior of Concrete Containing Alternative Pozzolan Calcined Marl Blended Cement,” Periodica Polytechnica Civil Engineering, vol. 64, no. 4, pp. 1087–1099, Jan. 2020, doi: 10.3311/PPci.15122.
34. W. Kurdowski and T. Baran, “Calcined marl as a potential main component of cement,” Cement-Wapno-Beton = Cement Lime Concrete, vol. 27, no. 5, pp. 346–354, 2022, doi: 10.32047/CWB.2022.27.5.4.
35. Y. Ettahiri et al., “Comparative study of physicochemical properties of geopolymers prepared by four Moroccan natural clays,” Journal of Building Engineering, vol. 80, p. 108021, 2023, doi: https://doi.org/10.1016/j.jobe.2023.108021.
36. P. Talviste, A. Sedman, R. Mõtlep, and K. Kirsimäe, “Self-cementing properties of oil shale solid heat carrier retorting residue,” Waste Management and Research, vol. 31, no. 6, pp. 641–647, Mar. 2013, doi: 10.1177/0734242X13482033/ASSET/IMAGES/LARGE/10.1177_0734242X13482033-FIG3.JPEG.
37. A. Gnisci, “Preliminary characterization of hydraulic components of low-temperature calcined marls from the south of Italy,” Cem Concr Res, vol. 161, p. 106958, 2022, doi: https://doi.org/10.1016/j.cemconres.2022.106958.
38. F. Zunino and K. Scrivener, “Increasing the kaolinite content of raw clays using particle classification techniques for use as supplementary cementitious materials,” Constr Build Mater, vol. 244, p. 118335, May 2020, doi: 10.1016/J.CONBUILDMAT.2020.118335.
39. H. H. Murray and U. by Staff, “Clays, Survey,” Kirk-Othmer Encyclopedia of Chemical Technology, pp. 1–29, Apr. 2014, doi: 10.1002/0471238961.1921182204151302.a01.pub3.
40. TCMA, “Üye Fabrikalar,” https://www.turkcimento.org.tr/assets/site/images/map-of-factories-v2.jpg?ver=92032.
41. S. Ferreiro, M. M. C. Canut, J. Lund, and D. Herfort, “Influence of fineness of raw clay and calcination temperature on the performance of calcined clay-limestone blended cements,” Appl Clay Sci, vol. 169, pp. 81–90, Mar. 2019, doi: 10.1016/J.CLAY.2018.12.021.
42. K. Cwik, M. Broström, K. Backlund, K. Fjäder, E. Hiljanen, and M. Eriksson, “Thermal Decrepitation and Thermally-Induced Cracking of Limestone Used in Quicklime Production,” Minerals, vol. 12, no. 10, p. 1197, Oct. 2022, doi: 10.3390/MIN12101197/S1.
43. J. C. Pachon, K. R. Kowalski, J. K. Butterick, and A. R. Bacon, “Quantified Effects of Particle Refractive Index Assumptions on Laser Diffraction Analyses of Selected Soils,” Soil Science Society of America Journal, vol. 83, no. 3, pp. 518–530, May 2019, doi: 10.2136/SSSAJ2018.07.0274;JOURNAL:JOURNAL:26911027;REQUESTEDJOURNAL:JOURNAL:14350661;PAGE:STRING:ARTICLE/CHAPTER.
44. C. N. Achilles et al., “Amorphous Phase Characterization Through X-Ray Diffraction Profile Modeling: Implications for Amorphous Phases in Gale Crater Rocks and Soils,” 2018.