Methods for improving volume stability of steel slag as fine aggregate

Abstract

Suitable methods for enhancing the volume stability of steel slag utilized as fine aggregate were determined. The effects of steam treatment at 100 °C and autoclave treatment under 2.0 MPa on the soundness of steel slag sand were investigated by means of powder ratio, linear expansion, compressive and flexural strength. DTA, EDX, XRD and ethylene glycol methods were employed to analyze both the treated slags and susceptible expansion grains. Experimental results indicate that powder ratio, content of free lime and rate of linear expansion can express the improvement in volume stability of different treated methods. Steam treatment process cannot ultimately prevent specimens from cracking and decrease of strength, but mortar made from autoclave treated slag keeps integration subjected to hot water of 80 °C until 28 d and its strength do not show significant decrement. The hydration of over-burn free lime and periclase phase are the main cause for the disintegration or crack of untreated and steam treated steel slag’s specimens. Autoclave treatment process is more effective than steam treatment process on enhancement of volume stability of steel slag.

Keywords

steel slag / fine aggregate / volume stability / steam treatment process / autoclave treatment process

References

[1] Zhu G. L., Sun S. H. An Urgent Task of Accelerating the Resource Recovery of Steel Slag[J]. Iron & Steel Scrap of China, 2006, 6(6): 33-42.

[2] Montgomery D. G., Wang G. Instant-chilled Steel Slag Aggregate in Concrete-Fracture Related Properties[J]. Cement and Concrete Research, 1992, 22(5): 755-760.

[3] Montgomery D. G., Wang G. Instant-chilled Steel Slag Aggregate in Concrete-Strength Related Properties[J]. Cement and Concrete Research, 1991, 21(6): 1 083-1 091.

[4] Xue Y. J., Wu S. P. Experimental Investigation of Basic Oxygen Furnace Slag Used as Aggregate in Asphalt Mixture[J]. Journal of Hazardous Materials, 2006, 138(2): 261-268.

[5] Huang Y., Bird R. N., Heidrich O. A Review of the Use of Recycled Solid Waste Materials in Asphalt Pavements[J]. Resources, Conservation and Recycling, 2007, 52(1): 58-73.

[6] Hu S. G., He Y. J., Lu L. N., . Effect of Fine Steel Slag Powder on the Early Hydration Process of Portland Cement[J]. Journal of Wuhan University of Technology-Materials Science Edition, 2008, 21(1): 147-149.

[7] Motz H., Geiseler J. Products of Steel Slag an Opportunity to Save Natural Resources[J]. Waste Management, 2001, 21(3): 285-293.

[8] Xiao Q. Z. Expansion and Its Inhibition of Steel Slag[J]. Journal of the Chinese Ceramic Society, 1996, 24(6): 635-640.

[9] Han Y. M., Jung H. Y., Seong S. K. A Fundamental Study on the Steel Slag Aggregate for Concrete [J]. Geosystem Engineering, 2002, 5(2): 38-45.

[10] Akın Altuna I., Smail Yılmaz I. Study on Steel Furnace Slags with High MgO as Additive in Portland Cement [J]. Cement and Concrete Research, 2002, 32(8): 1 247-1 249.

[11] Y H Xu. Progress on Turning Steel Slag into Energy in Japan [J]. Foreign Science and Technology, 1996, (12):36–37. (in Chinese)

[12] C J Shi. Steel Slag—Its Production, Processing, Characteristics, and Cementitious Properties [J]. Journal of Materials in Civil Engineering, 2004, (05–06):230–236