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Slag properties 2011
- 1. PROPERTIES OF AN EAF SLAG PRODUCED IN GREECE: A CONSTRUCTION MATERIAL FOR SUSTAINABLE GROWTH D. Xirouchakis. GeoTerra Ltd V. Manolakou. Greensteel S.A. 5th ICONFBMP_255 June 02, 2011 1
- 2. 5th ICONFBMP_255 June 02, 2011 2 Use of Steel Slags in EU (~30% is EAF slag)
- 3. Under the microscope Gravel 10/16 2x2 mm SXRF Fe map Sub-angular to angular, slightly porous grains Dendritic micro-texture Wüstite, Fe-Ti spinel, Ca-Mg-Fe olivine, Mg-gehlenite, gordonite, Ca-Mg carbonates 5th ICONFBMP_255 June 02, 2011 3
- 4. Major oxides 5th ICONFBMP_255 June 02, 2011 4
- 5. Heavy metals 5th ICONFBMP_255 June 02, 2011 5
- 6. Radioactivity 5th ICONFBMP_255 June 02, 2011 6
- 9. SE: 54 & 74% & MB: 0.25
- 10. ρα > 3.1 Mg/m3 & WA24 < 2.5%
- 11. ρb : 1.500 & 1.700 Mg/m3
- 12. MS < 6% & VLA < 3
- 13. LA ≤ 20 & MDE≥ 8
- 14. PSV ≥ 54 & AAV < 3
- 15. V < 3.5%
- 16. Adhesion (24 h) 75 – 95%High Specification Aggregates (HSA)
- 17. FI vs. SI 5th ICONFBMP_255 June 02, 2011 8
- 18. MB vs. SE 5th ICONFBMP_255 June 02, 2011 9
- 19. MDE vs. LA LA = 4.42·MDE0.631 5th ICONFBMP_255 June 02, 2011 10
- 20. PSV vs. AAV 5th ICONFBMP_255 June 02, 2011 11
- 21. Asphalt – aggregate adhesion SiO2 CaO 5th ICONFBMP_255 June 02, 2011 12
- 23. Strong affinity to heavy metals but negligible tendency to release them
- 24. Low corrosion potential, alkaline conditions
- 25. “Clean” material, low MBV & high SE
- 27. Very good adhesion to asphalt5th ICONFBMP_255 June 02, 2011 13
Editor's Notes
- Properties of an EAF slag produced in two facilities in Greece, Volos and Aspropyrgos. Talk outline:composition, mineralogy, and environmental stability as deduced from the distribution coefficient and retardation factor of heavy metals.Geometrical, physical, and mechanical properties with comparisons to natural aggregates and correlations among properties.Finally, conclusions.For any questions regarding production details the audience should ask Mrs Manolakou who is also here.
- Slags are a co-product of the iron and steelmaking process. After conditioning, screening, crushing, and washing, the processed material is an artificial aggregate possessing many advantages over natural aggregates. In the case of the GreenSteel slags, the materials are left to cool, cured with air- and water-spraying, and left to age for days to weeks. Uses of steel slags in EU.
- Slag aggregates. PLM image. SXRF Fe mar from BNL.
- Ternary projection of composition. Compare to andesite, limestones, and iron ore.
- Heavy metal content is high. Definitely higher than limestones but not always above the limits that are established in several EU countries. Cr is obviously the major concern and this is something that we will address later in this talk.
- The produced slag aggregates are deemed safe based on the guidelines established by IAEA and certainly the levels between the slag and the limestones are comparable.
- The data concern sand, gravel, and all-in aggregates. And the fractions produced are 0/4, 4/12, 10/16, and all-in 0/32.
- The elongation of grains, which affects packing, is measured in construction materials laboratories by the flakiness and shape index Both indices are low. Compared to limestones, the data for the GreenSteel slag are lower suggesting cubical/sub-round grains. Furthermore, the nearly 1:1 correlation between FI and SI appears independent of material and aggregate fraction. Note, for example, the dashed line of Peturrson et al. (2000) that was fitted to Icelandic basaltic aggregates.
- The slag aggregates, specifically, the 0/4 and 0/32 fractions are clean materials, i.e., they lack clays. This shows on the SE and MB values, which are respectively high and low. Also shown here is the negative correlation between SE and MB for limestone sand and all-in aggregates. This correlation is based only on the GeoTerra data. The data of Nikolaidis et al are simply for comparison. The negative correlation holds if we look at the nonlimestone aggregates but the numbers are understandably different.
- The slag gravel examined have low LA and MD values. Certainly comparable if not better than igneous volcanics from Greece and Bulgaria, and have consistently lower values than the limestone aggregates we have examined in the laboratory of GeoTerra. The dashed line is from a study based on greekmaficvolcanics.
- If we also look at the PSV and AAV numbers we see that the slag aggregates of this study exhibit high PSV and low AAV, which makes them excellent for use in asphalt-aggregate mixtures. For comparison, we also give the values for Fe- and Pb- (low) slags, igneous volcanics, and limestones from GR, IT, and CY. The fitting equations are from Hunter and Thompson et al., which seem to separate the PSV-AAV field to high specification aggregates and low specification aggregates with respect to PSV and AAV.
- The rolling bottle adhesion test shows that the GreenSteel EAF slag has a strong affinity for bitumen, comparable to that of limestone aggregates, and higher than that of igneous rock aggregates. Such an affinity is in agreement with the CaO-rich composition of the examined EAF slag samples. In conclusion, we can add to the notion that negatively-charged SiO2-rich rocks are more difficult to coat than positively-charged CaO-rich rocks that SiO2-rich rocks also lose their coating faster in the presence of water and under mechanical stress.