Alkali-reactive aggregates: corrosion and protection of concrete

Introduction. One type of concrete corrosion is caused by the chemical interaction of amorphous silica in aggregates with alkalis in the cement paste. This process develops slowly, and damage to the concrete is often detected only several years after construction is completed. Initially, damage caused by alkali-silica reaction was observed in large structures such as dams, bridges, and road pavements. Repairing and protecting damaged concrete structures is considered a complex process. The present paper addresses issues related to the prevention and protection of structures affected by this type of corrosion.

Aim. To evaluate methods for protecting concrete from internal alkali corrosion.

Materials and methods. The paper presents the results of determining the reactivity of aggregates from crushed stone and sand of various deposits. A method for protecting against alkali corrosion using lithium nitrate solution for impregnating concrete was tested in the process. To accelerate the impregnation process, concrete was treated with a direct current.

Results. The study demonstrates the inconsistency of results obtained through standard testing methods. The most reliable results are achieved through long-term testing (at least one year) of concrete made with the studied aggregates and cements. The study involved assessing feasibility of repairing concrete with signs of alkali corrosion through impregnation with lithium compound solutions while applying electric current.

Conclusions. The expansion of concrete due to alkali corrosion from aggregates sourced from various deposits has been investigated. The study confirmed the necessity for long-term testing of concretes using aggregates of specific suppliers, considering the characteristics of the applied cements and mineral additives. The authors examined the potential for protecting concrete from alkali corrosion through the introduction of lithium compound additives, including the use of current. The application of current accelerates the impregnation of concrete with lithium salt solutions; however, it poses certain challenges. Impregnation of the outer layer creates conditions for cracking due to differences in deformation between the outer layer and the inner layers that have not undergone impregnation. If the reactivity of the aggregate with cement alkalis is suspected, it is recommended to introduce finely ground silica-containing additives into the concrete to bind alkalis and prevent the development of concrete damage.

1. <i> Stanton T.E.</i> Expansion of concrete through reaction between cement and aggregate. Transactions of the

2. American Society of Civil Engineers. 1942;107(1):54–84. https://doi.org/10.1061/taceat.0005540

3. <i>Viktorov A.M., Lozhkin A.N.</i> The problem of alkaline corrosion of concrete dams. Gidrotekhnicheskoe Stroitel’stvo. 1992;(11):52–53. (In Russian).

4. Viktorov A.M. Causes of alkaline corrosion of concrete dams. Hydraulic engineering construction. 1992;(11). (In Russian).

5. <i>Viktorov A.M.</i> Prevention of alkaline corrosion of wetted concrete. Beton i Zhelezobeton = Concrete and Reinforced Concrete. 1986;(8):36–38. (In Russian).

6. <i>Moskvin V.M., Royak G.S.</i> Corrosion of concrete under the action of cement alkalis on silica fillers. Moscow:

7. Gosstroyizdat Publ.; 1962. (In Russian).

8. <i>Royak G.S.</i> On the composition and hydration of alkali-containing phases of cement. Cement. 1958;(5):21–24.

9. (In Russian).

10. <i>Royak G.S.</i> Alkalis in cement and the durability of concrete. Beton i Zhelezobeton = Concrete and Reinforced Concrete. 1959;(7):295–299. (In Russian).

11. <i>Moskvin V.M., Royak G.S.</i> One of the difficult issues of concrete corrosion. Izvestiya Akademii stroitel’stva i arkhitektury SSSR. 1961;(4):48–53. (In Russian).

12. State Standard 8269.0-97. Mauntainous rock road-metal a nd gravel, industrial waste products for construction works methods of physical and mechanical tests. Moscow: Standartinform Publ.; 2018. (In Russian).

13. <i>Ivanov F.M.</i> Internal corrosion of con crete. Beton i Zhelezobeton = Concrete and Reinforced Concrete. 1992;(8):8–10. (In Russian).

14. <i>Buyanov Yu.D., Kharo O.E., Butkevich G.R., Levkova G.S.</i> Prospects for improving concrete aggregates. Beton i Zhelezobeton = Concrete and Reinforced Concrete. 2005;(4):26–29. (In Russian).

15. <i>Lopatnikov M.I., Tedeev T.R.</i> Sand and gravel deposits as possible sources of local durable raw materials. Stroitel’nye Materialy = Construction Materials. 2007;(5):18–19. (In Russian).

16. <i>Buyanov Yu.D., Levkova N.S.</i> The influence of the quality of aggregates on the durability and corrosion resistance of structures. In: Durability and protection of structures from corrosion. Proceedings of the International Conference. Moscow; 1999, pp. 255–260. (In Russian).

17. <i>Rosenthal N.K., Lyubarskaya G.V., Rosenthal A.N.</i> Testing of concrete on reactive aggregates. Beton i Zhelezobeton = Concrete and Reinforced Concrete. 2014;(5):24–29. (In Russian).

18. State Standard 8267-93. Crushed stone and gravel of solid rocks for construction works. Specifications. Moscow: Standartinform Publ.; 2018. (In Russian).

19. State Standard 8736-93. Sand for construction works. Specifications. Moscow: Standartinform Publ.; 2009. (In Russian).

20. State Standard 26633-91. Heavy-weight and sand concretes. Specifications. Moscow: Standartinform Publ.; 2005. (In Russian).

21. <i>Mubarakshin R.K., Stroginov V.F.</i> About some quality problems in the construction practice of the Republic of Tatarstan. News of the Kazan State University of Architecture and Engineering. 2009;(2):15–21. (In Russian).

22. <i>Izotov V.S.</i> Features of alkaline corrosion and salinity formation in concrete on mixed binders. News of the Kazan State University of Architecture and Engineering. 2003;(1):68–69. (In Russian).

23. <i>Thomas M.D., Fournier B., Folliard K.J., Ideker J.H., Resendez Y.</i> The use of lithium to prevent or mitigate alkali-silica reaction in concrete pavements and structures. No. FHWA-HRT-06-133. Turner-Fairbank Highway Research Center; 2007.

24. <i>Whitmore D., Abbott S.</i> Use of an applid electric fields us drive lithium ions into alcali-silica reactive structure. In: Proceedings of the 11 International Conference on Alcali-Aggregate Reaction in Concrete. Quebec, Canada; 2000, pp. 1089–1098.

25. <i>Rosenthal N.K., Chekhov G.V., Lyubarskaya G.V., Rosenthal A.N.</i> Protection of concrete on a reactive aggregate from internal corrosion by lithium compounds. Stroitel’nye Materialy = Construction Materials. 2009;(3):68–71. (In Russian).

26. <i>McCoy W.J., Caldwell A.G.</i> New approach to inhibiting alkali-aggregate expansion. Journal of the American Concrete Institute. 1951;47(5):693–706. https://doi.org/10.14359/12030