Rebar Corrosion Potential in Alkali-Activated Slag and Pumice Mortars

Document Type : Original Article

Authors

1 Department of Civil Engineering, Faculty of Civil and Earth Resources Engineering, Central Tehran Branch, Islamic Azad University, Tehran, Iran

2 Concrete Technology and Durability Research Center (CTDRc), Department of Civil & Environmental Engineering, Amirkabir University of Technology, Tehran, Iran

Abstract

Previous researches have shown that due to its good adhesion, alkali-activated materials can be used as a protective overlay for concrete structures. However, the mechanical properties and durability of alkali-activated materials are not fully investigated. In this paper, compressive strength, bond strength, water penetration and half-cell corrosion potential of alkali-activated slag and pumice mortars as concrete overlay are investigated. The results show that the performance of alkali-activated slag mortar is better than Portland cement one in above tests and the use of potassium hydroxide as activator and a mixture of 90% slag and 10% pumice as based material result in the highest compressive strength and bond strength and the lowest water permeability and half-cell corrosion potential. The initial half-cell potential reading of alkali-activated mortar specimens was an average of 1.9 times more than Portland cement mortar specimens. This difference indicates that the ranges presented in ASTM C876 and their relationship with rebar corrosion risks are not applicable for alkali-activated materials and it is necessary to provide other criteria for these materials. Also, due to different conductivity of alkali-activated and Portland cement mortars, applying potential difference to accelerate the penetration of chloride ions and comparing the performance of alkali-activated materials with Portland cement is not a correct method. However, this method is suitable for comparing mixes design of alkali-activated mortars and the its results are in accordance with non-accelerated methods.

Keywords

Main Subjects


  1. Abhishek H.S., Prashant Sh., Kamath M.V., Kumar M. (2022). Fresh mechanical and durability properties of alkali‑activated fly ash‑slag concrete: a review. Innovative Infrastructure Solutions
  2. Salazara R. R., Jesúsb C., Gutiérreza R. M., Torgalb F. P. (2019). Alkali-activated binary mortar based on natural volcanic pozzolan for repair applications. Journal of Building Engineering 25
  3. Jiao Z., Wanga Y., Zheng W., Huang W., Zhao Y. (2019). Bond properties of alkali-activated slag concrete hollow block masonry with different mortar strength grades. Construction and Building Materials p.p. 149-165
  4. Fan J., Zhu H., Shi J., Li Z., Yang S. (2020). Influence of slag content on the bond strength, chloride penetration resistance, and interface phase evolution of concrete repaired with alkali activated slag/fly ash. Construction and Building Materials
  5. Shi, C. (1996). Strength, pore structure and permeability of alkali-activated slag mortars. Concr. Res. 26 (12), p. p. 1789–1799.
  6. Zhang Z., Yao X., Zhu H. (2010). Potential application of geopolymers as protection coatings for marine concrete: I. Basic properties. Applied Clay Science 49, p. p. 1-6.
  7. Bondar D. (2009). Alkali activation of Iranian natural pozzolans for producing geopolymer cement and concrete. A dissertation submitted to University of Sheffield in fulfilment of the requirements for the degree of Doctor of Philosophy, UK.
  8. ACI Committee 222. (1985). Corrosion of Metals in Concrete. ACI Materials.
  9. A. Ramezanianpour, T. Parhizkar، A.R. Pourkhorshidi, A.M. Raisghasemi. (1996). The effect of environmental conditions on the southern coast of Iran on the long-term durability of concrete with different cements and pozzolans. Building and Housing Research Center 434, (In Persian).
  10. Gu, P., Beaudoin, J.J. (1998). Construction Technology Update No. 18, Obtaining Effective Half- Cell Potential Measurements in Reinforced Concrete Structures. Institute of Research in Construction. National Research Council of Canada, Ottawa, Canad.
  11. Wheat, H.G. (1992). Corrosion behavior of steel in concrete made with Pyrament blended cement. Concr. Res. 22, p. p. 103–111.
  12. Glasser, F.P. (2001). Mineralogical aspects of cement in radioactive waste disposal. Mag. 65 (5), p. p. 621–633.
  13. Hossain M.M., Karim M.R., Elahi M.M.A., Islam M.N., Zain M.F.M.. (2020). Long-term durability properties of alkali-activated binders containing slag, fly ash, palm oil fuel ash and rice husk ash. Construction and Building Materials
  14. Kukko, H., Mannonen, R. (1982). Chemical and mechanical properties of alkali-activated blast furnace slag (F-concrete). Concr. Res. 1, p. p. 16.1–16.16.
  15. Deja, J., Małolepszy, J., Jaskiewicz, G. (1991). Influence of chloride corrosion on durability of reinforcement in the concrete. 2nd International Conference on the Durability of Concrete, p. p. 511–521. Montreal, Canada. American Concrete Institute.
  16. Małolepszy, J., Deja, J., Brylicki, W. (1994). Industrial application of slag alkaline concretes. Proceedings of the First International Conference on Alkaline Cements and Concretes, vol. 2, p. p. 989–1001. Kiev, Ukraine. VIPOL Stock Company.
  17. Bernal, S.A. (2009). Carbonatación de Concretos Producidos en Sistemas Binarios de una Escoria Siderúrgica y un Metacaolín Activados Alcalinamente, Ph.D. thesis, Universidad del Valle. Cali.
  18. Jafari Nadoushan M.; Ramezanianpour A.A. (2016). The effect of type and concentration of activators on flowability and compressive strength of natural pozzolan and slag-based geopolymers. Construction and Building Materials 111: 337-347.
  19. ASTM C778 – 12. (2012). Standard Specification for Standard Sand. ASTM Publication, United States.
  20. ASTM C305 – 12. (2012). Standard Practice for Mechanical Mixing of Hydraulic Cement Pastes and Mortars of Plastic Consistency. ASTM Publication, United States.
  21. ASTM C39– 12. (2012). Standard Test Method for Compressive Strength of Cylindrical Concrete Specimens. ASTM Publication, United States.
  22. Momayez, A. (2009). Laboratory study and modeling of methods for evaluating the strength of the connection between repair materials and old concrete. PhD thesis, Amirkabir University of Technology.
  23. Lee H.S., Jang H., Cho K.H. (2016). Evaluation of Bonding Shear Performance of Ultra-High-Performance Concrete with Increase in Delay in Formation of Cold Joints. Journal of Materials, 9. p. p. 362-377
  24. BS EN 12390-8. (2012) Testing hardened concrete- Part 8: Depth of penetration of water under pressure. British Standard (In Persian).
  25. ASTM C876– 12. (2012). Standard Test Method for Half-Cell Potentials of Uncoated Reinforcing Steel in Concrete. ASTM Publication, United States.
  26. Haider M. Giasuddin, Jay G. Sanjayan, P.G. Ranjith. (2013). Strength of geopolymer cured in saline water in ambient conditions. Journal of Fuel 107, p. p. 34–39.
  27. Douglas, E., Bilodeau, A., Malhotra, V.M. (1992). Properties and durability of alkali-activated slag concrete. ACI Mater. J. 89 (5), p. p. 509–516.
  28. Sofi M., Deventer J.S.J., P.A. Mendis, G.C. Lukey. (2007). Engineering properties of inorganic polymer concretes (IPCs). Cement and Concrete Research 37, p.p. 251–257.
  29. Castel A. and Foster S. J.. (2015). Bond strength between blended slag and Class F fly ash geopolymer concrete with steel reinforcement. Cement and Concrete Research, p. p. 48-53.
  30. Holloway, M., Sykes, J.M. (2005). Studies of the corrosion of mild steel in alkali-activated slag cement mortars with sodium chloride admixtures by a galvanostatic pulse method. Corros Sci. 47 (12), p. p. 3097–3110.
  31. Aperador, W., Mejía de Gutierrez, R., Bastidas, D.M. (2009). Steel corrosion behaviour in carbonated alkali-activated slag concrete. Sci. 51 (9), p. p. 2027–2033.
  32. Ibrahim M., Rahman M. K., Johari M. A. M., Nasir M., Oladapo E. A. (2020). Chloride diffusion and chloride-induced corrosion of steel embedded in natural pozzolan-based alkali activated concrete. Construction and Building Materials