Investigation into the microstructural and mineralogical changes induced by internal swelling reactions in concrete used for nuclear power plants – a mock-up study

Abstract

Extending the lifetime of existing nuclear facilities is becoming in-creasingly relevant to ensure the continued generation of electricity with a low carbon footprint. For this purpose, a thorough assessment is required of the potential pathologies that may arise and affect the integrity of existing concrete support structures. Of particular interest are internal swelling reac-tions, such as delayed ettringite formation (DEF) and alkali-silica reaction (ASR), which can cause swelling and cracking of concrete. While these pro-cesses have been well-researched at a laboratory scale, controlled studies at a larger scale are more scarce. To simulate the effects of these processes on a larger scale, concrete mock-ups were constructed, subjected to elevated tem-perature and humidity, and monitored, after which the mock-ups were sam-pled for further characterization. The purpose of this study was to conduct a detailed investigation of this type of concrete to assess whether the macro-scopic effects of the swelling reactions had a significant impact on the mi-crostructure and mineralogy, i.e. to investigate the effect of the dissolution or precipitation of phases induced by internal swelling reactions. The findings indicated that the bulk mineralogy and pore size distribution of the concrete samples were not significantly altered by either DEF or ASR. However, elec-tron microscopy imaging revealed significant amounts of cracking across all samples, which was associated with infilling by either ettringite crystals or ASR gel, depending on the mock-up. The infilling of cracks explains the lim-ited effect of either process on the overall pore size distribution. Although the overall volumetric expansion in the mock-ups was significant, it was primarily associated with heterogeneous large-scale cracks, with only minor contributions from the microscopic fractures.

Keywords

Alkali-silica reaction / delayed ettringite formation / mineralogy / microstructure

References

[1] Odler I, Chen Y. Effect of cement composition on the expansion of heat-cured cement pastes. Cement and Concrete Research, 1995, 25: 853-862

[2] Godart, B., & Divet, L. (2013). Lessons learned from structures damaged by delayed ettringite formation and the French prevention strategy. Proceedings of the Fifth International Conference on Forensic Engineering, Institution of Civil Engineers, 12.

[3] Godart B. Pathology, assessment and treatment of structures affected by delayed ettringite formation. Structural Engineering International, 2017, 27: 362-369

[4] Flatt RJ, Scherer GW. Thermodynamics of crystallization stresses in DEF. Cement and Concrete Research, 2008, 38: 325-336

[5] Pavoine A, Brunetaud X, Divet L. The impact of cement parameters on delayed ettringite formation. Cement and Concrete Composites, 2012, 34: 521-528

[6] Kelham S. The effect of cement composition and fineness on expansion associated with delayed ettringite formation. Cement and Concrete Composites, 1996, 18: 171-179

[7] Kunther W, Lothenbach B, Skibsted J. Influence of the Ca/Si ratio of the C-S–H phase on the interaction with sulfate ions and its impact on the ettringite crystallization pressure. Cement and Concrete Research, 2015, 69: 37-49

[8] Sellier A, Multon S. Chemical modelling of delayed ettringite formation for assessment of affected concrete structures. Cement And Concrete Research, 2018, 108: 72-86

[9] Barbarulo R, Peycelon H, Prené S, Marchand J. Delayed ettringite formation symptoms on mortars induced by high temperature due to cement heat of hydration or late thermal cycle. Cement and Concrete Research, 2005, 35: 125-131

[10] Taylor H, Famy C, Scrivener K. Delayed ettringite formation. Cement and Concrete Research, 2001, 31: 683-693

[11] Jebli M, Jamin F, Pelissou C, Lhopital E, El Youssoufi M. Characterization of the expansion due to the delayed ettringite formation at the cement paste-aggregate interface. Construction and Building Materials, 2021, 289 122979

[12] Stark J, Bollmann K. Delayed ettringite formation in concrete. NORDIC CONCRETE RESEARCH-PUBLICATIONS-, 2000, 23: 4-28

[13] Escadeillas G, Aubert J-E, Segerer M, Prince W. Some factors affecting delayed ettringite formation in heat-cured mortars. Cement and Concrete Research, 2007, 37: 1445-1452

[14] Danfour A, Perko J, Seetharam S, Phung QT, Jacques D, Cizer Ö. Numerical study of potential delayed ettringite formation in cemented nuclear wasteforms. Sustainability, 2024, 16: 389

[15] Fournier B, Bérubé M-A. Alkali-aggregate reaction in concrete: A review of basic concepts and engineering implications. Canadian Journal of Civil Engineering, 2000, 27: 167-191

[16] Rajabipour F, Giannini E, Dunant C, Ideker JH, Thomas MD. Alkali–silica reaction: Current understanding of the reaction mechanisms and the knowledge gaps. Cement and Concrete Research, 2015, 76: 130-146

[17] Leemann A, Góra M, Lothenbach B, Heuberger M. Alkali silica reaction in concrete-Revealing the expansion mechanism by surface force measurements. Cement and Concrete Research, 2024, 176 107392

[18] Lokajíček T, Přikryl R, Šachlová Š, Kuchařová A. Acoustic emission monitoring of crack formation during alkali silica reactivity accelerated mortar bar test. Engineering Geology, 2017, 220: 175-182

[19] Leemann A, Münch B. The addition of caesium to concrete with alkali-silica reaction: Implications on product identification and recognition of the reaction sequence. Cement and Concrete Research, 2019, 120: 27-35

[20] Joo HE, Takahashi Y. Analytical and experimental studies on alkali-silica reaction mechanism: Aggregate cracking and chemical composition change of gel. Cement and Concrete Composites, 2023, 139 105003

[21] Kawabata Y, Dunant C, Yamada K, Scrivener K. Impact of temperature on expansive behavior of concrete with a highly reactive andesite due to the alkali–silica reaction. Cement and Concrete Research, 2019, 125 105888

[22] Berube M-A, Frenette J, Pedneault A, Rivest M. Laboratory assessment of the potential rate of ASR expansion of field concrete. Cement, Concrete, and Aggregates, 2002, 24: 13-19

[23] Diamond S, Ong S. Combined effects of alkali silica reaction and secondary ettringite deposition in steam cured mortars. Ceramic Transactions, 1993, 40: 79-90

[24] Yang R, Lawrence CD, Lynsdale CJ, Sharp JH. Delayed ettringite formation in heat-cured Portland cement mortars. Cement and Concrete Research, 1999, 29: 17-25

[25] Doug Hooton, R., Rogers, C., MacDonald, C.A., & Ramlochan, T. (2013). Twenty-Year Field Evaluation of Alkali-Silica Reaction Mitigation. ACI Materials Journal, 110.

[26] Fournier B, Ideker JH, Folliard KJ, Thomas MD, Nkinamubanzi P-C, Chevrier R. Effect of environmental conditions on expansion in concrete due to alkali–silica reaction (ASR). Materials characterization, 2009, 60: 669-679

[27] Lindgård J, Nixon PJ, Borchers I, Schouenborg B, Wigum BJ, Haugen M, Åkesson U. The EU “PARTNER” Project—European standard tests to prevent alkali reactions in aggregates: Final results and recommendations. Cement and Concrete Research, 2010, 40: 611-635

[28] Jabbour J, Darquennes A, Divet L, Bennacer R, Torrenti J-M, Nahas G. New experimental approach to accelerate the development of internal swelling reactions (ISR) in massive concrete structures. Construction and Building Materials, 2021, 313 125388

[29] Döbelin, N.; Kleeberg, R. Profex: a graphical user interface for the Rietveld refinement program BGMN. Journal of Applied Crystallography 2015, 48, 1573–1580.

[30] De Boer J, Lippens B, Linsen B, Broekhoff J, Van den Heuvel A, Osinga TJ. The t-curve of multimolecular N2-adsorption. Journal of Colloid and Interface Science, 1966, 21: 405-414

[31] Brunauer S, Emmett PH, Teller E. Adsorption of gases in multimolecular layers. Journal Of The American Chemical Society, 1938, 60: 309-319

[32] Barrett E, Joyner L, Halenda P. Pore size distribution for porous materials. Journal of the American Chemical Society, 1951, 73: 373-380

[33] Washburn EW. Note on a method of determining the distribution of pore sizes in a porous material. Proceedings of the National Academy of Sciences of the United States of America, 1921, 7: 115

[34] Patsikas N, Katsiotis N, Pipilikaki P, Papageorgiou D, Chaniotakis E, Beazi-Katsioti M. Durability of mortars of white cement against sulfate attack in elevated temperatures. Construction and Building Materials, 2012, 36: 1082-1089

[35] Akula P, Little DN. Mineralogical characterization and thermodynamic modeling of synthesized ettringite from Ca-Al-SO4 suspensions. Construction and Building Materials, 2021, 269 121304

[36] Phung, Q.T., Maes, N., & Jacques, D. (2017). Application of multiple techniques to quantify pore structure of degraded cementitious materials. Proceedings of the XIV DBMC 14th International Conference on Durability of Building Materials and Components, 217.

[37] Münch B, Holzer L. Contradicting geometrical concepts in pore size analysis attained with electron microscopy and mercury intrusion. Journal of The American Ceramic Society, 2008, 91: 4059-4067

[38] Tosun K, Baradan B. Effect of ettringite morphology on DEF-related expansion. Cement and Concrete Composites, 2010, 32: 271-280

[39] Roubin E, Al. Shamaa M, Colliat J-B, Pavoine A, Divet L, Torrenti J-M, Nahas G. A nonlinear meso–macro approach to modelling delayed ettringite formation and concrete degradation. Materials and Structures, 2014, 47: 1911-1920

[40] Gholizadeh-Vayghan A, Rajabipour F. The influence of alkali–silica reaction (ASR) gel composition on its hydrophilic properties and free swelling in contact with water vapor. Cement and Concrete Research, 2017, 94: 49-58

[41] Shi Z, Lothenbach B. The combined effect of potassium, sodium and calcium on the formation of alkali-silica reaction products. Cement and Concrete Research, 2020, 127 105914

Funding

EC Horizon2020 ACES(900012)

RIGHTS & PERMISSIONS

The Author(s)