Modified concrete based on activated metakaolin for tunnel structures with increased performance properties

Introduction. Due to the ever-increasing demands for the quality and reliability of concrete structures for tunnel construction, the task is to develop modified concretes with improved performance characteristics.

Materials and methods. This study examines issues related to the modification of the composition of heavyweight concrete with a complex chemical additive, which includes the Sunbo PC-1021 superplasticizer, the water-soluble polymer additive Polidon-A together with activated metakaolin. It has been established that the process of chemical activation of metakaolin particles has not been sufficiently studied. In this regard, the presented studies, which consist of finding solutions to improve performance characteristics due to the process of its preliminary treatment with an alkaline medium pH = 10 together with a micro-reinforcing component (wollastonite), are relevant.

Results. A positive effect of complex modification on the properties of heavy concrete was established by reducing the content of binder (cement) and replacing it with metakaolin, pre-activated in an alkaline medium with pH = 10 with a modifier and wollastonite, which improves the strength and hydrophysical characteristics: compressive strength at the age of 28 days was 68.6 MPa compared to the control composition - 39.4 MPa; water absorption - 2.4%; water resistance grade - W14.

Discussion and conclusions. The problem of obtaining effective concrete for tunnel structures with improved performance properties can be solved by modifying the binder in the composition with activated metakaolin together with a complex modifier of the mixture (PC + 5% MTK_akt + 0.4% SP + 0.3% Polidon-A + 2% wollastonite). The proposed composition makes it possible to manufacture reinforced concrete structures for tunnels with specified characteristics in production conditions, operating under conditions of increased load and aggressive environment.

1. Oreshkin D.V. Problems of construction materials science and production of construction materials. Stroitel’nye Materialy” (Construction Materials). 2010; 11: 6-8. (in Russ.)

2. Kaprielov S.S., Sheynfeld A.V., Chilin I.A., Dondukov V.G., Selyutin N.M. Modified concrete: reality and prospects. Bulletin of Science and Research Center of Construction. 2024; 40(1): 92–104. (In Russ.) DOI: https://doi.org/10.37538/2224-9494-2024-1(40)-92-104. EDN: NIYJLR

3. Krutskikh A.V., Petropavlovskaya V.B., Petropavlovskii K.S., Novichenkova T.B. Modified cement concrete with discrete reinforcement. Building and Reconstruction. 2023; (3): 131–139. (In Russ.) DOI: https://doi.org/10.33979/2073-7416-2023-107-3-131-139

4. Petropavlovskaya V.B., Zavad’ko M.Yu., Novichenkova T.B., Petropavlovskii K.S., Buryanov A.F. Assessment of the possibility of using hydraulic ash as a component of dry building mixtures. Part 1. Stroitel’nye Materialy [Construction Materials]. 2023; 4: 73–79. (In Russ.) DOI: https://doi.org/10.31659/0585-430X-2023-812-4-73-79

5. Velichko E.G., Shumilina Yu.S. To the problem of forming the high-strength concrete dispersed composition and properties. Vestnik MGSU [Monthly Journal on Construction and Architecture]. 2020; 15(2): 235–243. DOI:10.22227/1997-0935.2020.2.235-243 (Rus.).

6. Filimonova Yu.S., Velichko E.G. Research of complex modification of heavy concrete. Building and Reconstruction. 2021; (4): 107–112. (In Russ.) DOI: https://doi.org/10.33979/2073-7416-2021-96-4-107-112

7. Tkach E.V., Temirkanov R.I. Improving the physico-mechanical properties of modified concrete based on the use of chemically activated micro-silica with micro-reinforcing fiber. Building and Reconstruction. 2020; (2): 123–135. (In Russ.) DOI: https://doi.org/10.33979/2073-7416-2020-88-2-123-135

8. Shuldyakov K.V., Kramar L.Ya., Trofi- mov B.Ya., Mamaev N.A. Influence of the additive “microsilica-polycarboxylate superplasticizer” on cement hydration, structure and properties of cement stone. Cement and its Applications. 2013; 2: 114–118. (In Russ.)

9. Urkhanova L.A., Lkhasaranov S.A., Iva nov A.A. Optimization of the composition of hydraulic concrete using composite binders. Engineering and technology of silicates. 2023; V. 30. No. 4: 350–356. (In Russ.)

10. Aleksandrova O.V., Nguyen D.V.K., Bulga kov B.I., Petropavlovskaya V.B. The influence of quartz powder and miner al additives on the properties of high strength concrete. Bulletin of the Volga State Technological University. series: materials. designs. technologies. 2020; 3: 7–15. DOI: https://doi.org/10.25686/2542-114X.2020.3.7

11. Urkhanova L.A., Ivanov A.A., Lhasara nov S.A. Study of the influence of finely dispersed additives on the properties of composite binders for hydraulic concrete. ESSUTM Bulletin. 2023; 2 (89): 80–89. (In Russ.)

12. Urkhanova L.A., Lhasaranov S.A., Danza nov D.V. Synthesis of an ultradispersed additive obtained by hydrolysis of Portland cement for modifi-cation of cement stone. Cement and its Applications. 2022; 4: 52-56. (In Russ.)

13. Tomilov A.P. Electrochemical activation – a new direction in applied electrochemistry. Life and Safety. 2002; 3: 302–307.

14. Massana, J., Reyes, E., Bernal, J., Leon, N., Sanchez-Espinosa, E. Influence of nano- and micro-silica additions on the durability of a high-performance self-compacting concrete. Construction and Building Materials. 2018; 165: 93–103.

15. Larbi J.A., Bijen J.M. Effect of water-cement ratio, quantity and fineness of sand on the evolution of lime in set portland cement systems. Cement and Concrete Research. 1990; 20. no 5: 783–794.

16. Roberts L.R., Grace W.R. Microsilica in concrete. Materials Science of Concrete. 1989; 3: 197–222.