ORIGINAL PAPER
Polymorphic transformations of dicalcium silicates in steel slags used in the production of road aggregates
 
More details
Hide details
1
Silesian University of Technology, Faculty of Mining, Safety Engineering and Industrial Automation
2
Silesian University of Technology, of Civil Engineering
CORRESPONDING AUTHOR
Iwona Jonczy   

Silesian University of Technology, Faculty of Mining, Safety Engineering and Industrial Automation, Gliwice, Poland
Submission date: 2021-07-16
Final revision date: 2021-09-10
Acceptance date: 2021-11-12
Publication date: 2021-12-22
 
Gospodarka Surowcami Mineralnymi – Mineral Resources Management 2021;37(4):97–116
 
KEYWORDS
TOPICS
ABSTRACT
This paper presents results of mineralogical and chemical research connected with the polymorphic transformations of dicalcium silicates in aggregate based on open-hearth slag and also slags from the current production of EAF (electric arc furnaces), and LF (ladle furnaces). Particular attention was paid to the transformation of the polymorph β-Ca2[SiO4] into the variant γ-Ca2[SiO4], which is undesirable from the perspective of using steel slags in road construction. A full mineralogical characterization of the tested metallurgical slags enabled the verification of the effectiveness of detecting the decomposition of dicalcium silicate in observations in UV light in line with the PN-EN 1744-1+A1:2013-05 standard. On the basis of the conducted research, it was found that in the aggregate based on open-hearth slags and in the EAF furnace slag, dicalcium silicates are mainly represented by the β-Ca2[SiO4] polymorph, accompanied by α’-Ca2[SiO4]. The slag from the LF furnace was characterized by a different composition, with a strong advantage (57%) of the α’-Ca2[SiO4] variety, with a 1% share of the β-Ca2[SiO4] and 15% of the γ-Ca2[SiO4]. It was found that the transformation of β-Ca2[SiO4] into γ-Ca2[SiO4] can take place only under certain conditions in the metallurgical process, but the process is not influenced by hyperergenic factors, as evidenced by the fact that after more than 100 years of storage of open-hearth slag, on the basis of which the aggregate was produced, it was primarily marked with all the variants of β-Ca2[SiO4], without the polymorph γ-Ca2[SiO4]. The comprehensive characterization of the slag phase composition requires use of an appropriately selected research methodology; this is of key importance prior to the secondary use of this material, especially in the presence of the γ-Ca2[SiO4] polymorph. It has been determined that the most accurate test results are obtained using the XRD technique. The method of determining the decomposition of dicalcium silicate according to the PN-EN 1744-1+A1:2013-05 standard proved to be unreliable. It seems that in the situation of using LF slag as an artificial aggregate, taking the test results according to the method described in the PN-EN 1744-1+A1:2013-05 standard as being decisive is very risky, especially on a large scale (e.g. in communication construction).
ACKNOWLEDGEMENTS
The work is partially supported by the Ministry of Science and Higher Education funding for statutory activities of young researchers BKM-693/RB7/2020. We would like to thank the Management Board of the EkoProHut sp. z o.o. company for providing research materials and consultations during the research andthe preparation stage of this paper.
METADATA IN OTHER LANGUAGES:
Polish
Przemiany polimorficzne krzemianów dwuwapniowych w żużlach stalowniczych stosowanych do produkcji kruszywa drogowego
żużel stalowniczy, krzemiany dwuwapniowe, kruszywa sztuczne
W artykule przedstawiono wyniki badań mineralogiczno-chemicznych dotyczące przemian polimorficznych krzemianów dwuwapniowych w kruszywie na bazie żużli martenowskich, a także w żużlach z bieżącej produkcji pieca elektrycznego EAF (Electric Arc Furnace) oraz pieca kadziowego LF (Ladle Furnace). Szczególną uwagę zwrócono na przeobrażenia polimorfu β-Ca2[SiO4] w odmianę γ-Ca2[SiO4], co jest niepożądanym zjawiskiem z punktu widzenia wykorzystania żużli stalowniczych w budownictwie drogowym. Pełna charakterystyka mineralogiczna badanych żużli posłużyła do weryfikacji skuteczności wykrywania rozkładu krzemianu dwuwapniowego w obserwacjach w świetle UV zgodnie z normą PN-EN 1744-1+A1:2013-05. Na podstawie przeprowadzonych badań stwierdzono, że w kruszywie na bazie żużli martenowskich oraz w żużlu z pieca EAF krzemiany dwuwapniowe są reprezentowane przede wszystkim przez odmianę β-Ca2[SiO4], której towarzyszy α’-Ca2[SiO4]. Żużel z pieca LF charakteryzował się natomiast odmiennym składem, z silną przewagą (57%) odmiany α’-Ca2[SiO4], przy 1% udziale odmiany β-Ca2[SiO4] oraz przy 15% zawartości odmiany γ-Ca2[SiO4]. Stwierdzono, że przemiana β-Ca2[SiO4] w γ-Ca2[SiO4] może zachodzić tylko w określonych warunkach w procesie metalurgicznym, na proces ten nie mają natomiast wpływu czynniki hipergeniczne, o czym może świadczyć fakt, że po około 100-letnim okresie składowania żużla martenowskiego, na bazie którego wyprodukowano kruszywo, oznaczono w nim przede wszystkim odmianę β-Ca2[SiO4], nie stwierdzając polimorfu γ-Ca2[SiO4]. Kompleksowa charakterystyka składu fazowego żużla wymaga zastosowania odpowiednio dobranej metodyki badawczej, zwłaszcza pod kątem obecności polimorfu γ-Ca2[SiO4], co ma kluczowe znaczenie przed wtórnym wykorzystaniem tego materiału. Stwierdzono, że najdokładniejsze wyniki badań uzyskuje się przy użyciu techniki XRD. Metoda oznaczania rozkładu krzemianu dwuwapniowego wg normy PN-EN 1744-1+A1:2013-05 okazała się zawodna. Wydaje się, że w sytuacji wykorzystania żużla po produkcji pieca LF jako kruszywa sztucznego, zwłaszcza na dużą skalę, np. w budownictwie komunikacyjnym, przyjęcie wyników badań zgodnie z metodą opisaną w normie PN-EN 1744-1+A1:2013-05 jako decydujące jest bardzo ryzykowne.
 
REFERENCES (40)
1.
Adegoloye et al. 2013 – Adegoloye, G., Beaucour, A.L., Ortola, S. and Noumowe, A. 2013. Mineralogical characterisation of EAF and AOD slags using ultraviolet fluorescence. Proceedings of the Third International Slag Valorisation Symposium, The Transition to Sustainable Materials Management. Leuven, Belgium, 19–20 March 2013, pp. 347–350.
 
2.
Adegoloye et al. 2016 – Adegoloye, G., Beaucour, A. L., Ortola, S. and Noumowe, A. 2016. Mineralogical composition of EAF slag and stabilised AOD slag aggregates and dimensional stability of slag aggregate concretes.Construction and Building Materials 115, pp. 171–178.
 
3.
Alanyali et al. 2009 – Alanyali, H., Çöl, M., Yilmaz, M. and Karagöz, Ş. 2009. Concrete Produced by Steel-Making Slag (Basic Oxygen Furnace) Addition in Portland Cement. International Journal of Applied Ceramic Technology 6, pp. 736–748.
 
4.
Chan et al. 1992 – Chan, C.J., Kriven, W.M. and Young, J.F. 1992. Physical stabilization of the β → γ transformation in dicalcium silicate. Journal of the American Ceramic Society 75, pp. 1621–1627.
 
5.
Cioroi et al. 2010 – Cioroi, A.M., Nistor Cristea, L. and Cretescu, I. 2010. The treatment and minimization of metallurgical slag as waste. Environmental Engineering and Management Journal 1, pp. 101–106.
 
6.
Collins, R.J. and Sherwood, P.T. 1995. Use of waste and recycled materials as aggregates: standards and specifications, report prepared by the Building Research Establishment (BRE) for the Department of the Environment. London: HMSO.
 
7.
Dunster, A.M. 2002. Blast furnace slag and steel slag as aggregates: a review of their uses and applications in UK construction. Third European Slag Conference, Proceedings Manufacturing and Processing of Iron and Steel Slags, UK, pp. 21–29.
 
8.
European Standard EN 1744-1+A1:2013-05, Tests for chemical properties of aggregates, Part 1, Chemical analysis.
 
9.
Fidancevska et al. 2009 – Fidancevska, E., Vassilev, V., Hristova-Vasileva, T. and Milosevski, M. 2009. On a possibility for application of industrial wastes of metallurgical slag and tv-glass. Journal of the University of Chemical Technology and Metallurgy 44(2), pp. 189–196.
 
10.
Ghose et al. 1983 – Ghose, A., Chopra, S. and Young, J.F. 1983. Microstructural characterization of doped dicalcium silicate polymorphs. Journal of Materials Science 18(10), pp. 2905–2914.
 
11.
Green et al. 2018 – Green, D.J., Hannink, R.H.J. and Swain, M.V. 2018. Transformation toughening of ceramics. Boca Raton: CRC Press.
 
12.
Groves, G.W. 1983. Phase transformations in dicalcium silicate. Journal of Materials Science 18, pp. 1615–1624.
 
13.
Gutt, W. 1963. High-temperature phase equilibria in the partial sys-tem 2CaO · SiO2-2MgO · SiO2-A12O3 in the quaternary system CaO-SiO2-A12O3-MgO. Journal of the Iron and Steel Institute 201, pp. 532–536.
 
14.
Gutt, W. and Russell, A.D. 1977. Studies of the system CaO-SiO2-A12O3-MgO in relation to the stability of blast furnace slag. Journal of Materials Science 12, pp. 1869–1878.
 
15.
Hager, I. 2013. Behaviour of cement concrete at high temperature. Bulletin of the Polish Academy of Sciences: Technical Sciences 61, pp. 3–10.
 
16.
Henning, O. and Knöfel, D. 1982. Baustoffchemie. Wiesbaden: Bauverlag.
 
17.
Iacobescu et al. 2011 – Iacobescu, R.I., Koumpouri, D., Pontikes, Y., Şaban, R. and Angelopoulos, G. 2011. Utilization of EAF metallurgical slag in “GREEN” belite cement. UPB Scientific Bulletin, Series B 73(1), pp. 1454–2331.
 
18.
Jonczy, I. 2016. Microstructures of metallurgical slags. Archives of Metallurgy and Materials 61(1), pp. 61–66.
 
19.
Jonczy, I. and Stanek, J. 2013. Phase composition of metallurgical slag studied by Mössbauer spectroscopy. Nukleonika International Journal of Nuclear Research 58(1), pp. 127–131.
 
20.
Juckers, L.M. 2002. Dicalcium silicate in blast-furnace slag: a critical review of the implications for aggregate stability. Mineral Processing and Extractive Metallurgy 111, pp. 120–128.
 
21.
Kim, Y.-M. and Hong, S.-H. 2004. Influence of minor ions on the stability and hydration rates of β-dicalcium silicate. The Journal of the American Ceramic Society 87, pp. 900–905.
 
22.
Kriskova et al. 2014 – Kriskova, L., Pontikes, Y., Zhang, F., Cizer, Ö., Jones, P.T., Van Balen, K. and Blanpain, B. 2014. Influence of mechanical and chemical activation on the hydraulic properties of gamma dicalcium silicate. Cement and Concrete Research 55, pp. 59–68.
 
23.
Mindat.org [Online:] https://www.mindat.org/min-957... [Accessed: 2021-02-27].
 
24.
Nikolaides, A. 2014. Highway engineering. Pavements, Materials and Control of Quality. Boca Raton: CRC Press.
 
25.
Rai et al. 2002 – Rai, A., Prabakar, J., Raju, C.B. and Morchalle, R.K. 2002. Metallurgical slag as a component in blended cement. Construction and Building Materials 16(8), pp. 489–494.
 
26.
Rajczyk, K. 1990. Effect of a reducing atmosphere on the properties of dicalcium silicate. Cement and Concrete Research 20, pp. 36–44.
 
27.
Reddy et al. 2006 – Reddy, A.S., Pradhan, R.K. and Chandra, S. 2006. Utilization of basic oxygen furnace (BOF) slag in the production of a hydraulic cement binder. International Journal of Mineral Processing 79(2), pp. 98–105.
 
28.
Setién et al. 2009 – Setién, J., Hernández, D. and González, J. J. 2009. Characterization of ladle furnace basic slag for use as a construction material. Construction and Building Materials 23, pp. 1788–1794.
 
29.
Shen et al. 2004 – Shen, H., Forssberg, E. and Nordström, U. 2004. Physicochemical and mineralogical properties of stainless steel slags oriented to metal recovery. Resources, Conservation & Recycling 40, pp. 245–271.
 
30.
Sherwood, P.T. 1995. Alternative materials in road construction, London: Thomas Telford.
 
31.
Shi, C. 2004. Steel slag – its production, processing, characteristics, and cementitious properties. Journal of Materials in Civil Engineering 16(3), pp. 230–236.
 
32.
Shi, C. and Hu, S. 2003. Cementitious properties of ladle slag fines under autoclave curing conditions. Cement and Concrete Research 33, pp. 1851–1856.
 
33.
Smith et al. 1965 – Smith, D.K., Majudor, A. and Ordway, F. 1965. The crystal structure of γ-dicalcium silicate. Acta Crystallographica 18, pp. 787–795.
 
34.
Sofilić et al. 2010 – Sofilić, T., Merle, V., Rastovčan-Mioč, A., Ćosić, M. and Sofilić, U. 2010. Steel slag instead natural aggregate in asphalt mixture. Archives of Metallurgy and Materials 55(3), pp. 657–668.
 
35.
Sorlini et al. 2012 – Sorlini, S., Sanzeni, A. and Rondi, L. 2012. Reuse of steel slag in bituminous paving mixtures.Journal of Hazardous Materials 209–210, pp. 84–91.
 
36.
Taylor, H.F.W. 1990. Cement Chemistry, London: Academic press.
 
37.
Wawrzeńczyk et al. 2016 – Wawrzeńczyk, J., Juszczak, T. and Molendowska, A. 2016. „Determining equivalent performance for frost durability of concrete containing different amounts of ground granulated blast furnace slag. Bulletin of the Polish Academy of Sciences: Technical Sciences 64, pp. 731–737.
 
38.
Wieczorek, A.N. and Jonczy, I. 2019. Mineralogical and chemical characteristics of metallic precipitations in selected types of steelmaking slags and in blast furnace slags. Gospodarka Surowcami Mineralnymi – Mineral Resources Management 35(4), pp. 69–84.
 
39.
Wyderko-Delekta M. and Bolewski A. 1995. Mineralogy of sinters and ores (Mineralogia spieków i grudek rudnych). Kraków: AGH Publishing House (in Polish).
 
40.
Xu, D. and Li, H. 2009. Future resources for eco-building materials: I. Metallurgical slag. Journal of Wuhan University of Technology, Materials Science Edition 24(3), pp. 451–456.
 
eISSN:2299-2324
ISSN:0860-0953