Concrete leaching of a hydroelectric powerhouse due to 40 years of exposure to river water

Neumann, Claudio; Faria, Étore Funchal de; Santos, Arturo

doi:10.1016/j.conbuildmat.2021.124253

Cited by 23 publications

(8 citation statements)

References 17 publications

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“…Concrete structures in contact with water deteriorate due to leaching, which affects their serviceability, especially in drinking water treatment plants or dams [1]. Repair works usually require the temporary closure of the water treatment plant, and another plant must, therefore, take over during this period, which might result in considerable deleterious impacts.…”

Section: Introductionmentioning

confidence: 99%

“…To maintain the leaching over time, samples can also be immersed into a large container, and no renewals are made [8,[19][20][21][22], but the risk is that the deterioration ends up slowing down and stopping after a few days or weeks. In order to accelerate deterioration, numerous studies have been performed using nitrate ammonium solutions [1,23]. Another possibility is renewing periodically the leaching solution and controlling the pH in the interval [8,24,25].…”

Section: Introductionmentioning

confidence: 99%

“…Another possibility is renewing periodically the leaching solution and controlling the pH in the interval [8,24,25]. Studies often consider the composition of water in order to combine different attack mechanisms, e.g., an external sulphate attack and leaching [26][27][28], or focus on specific in situ cases [1,29]. Therefore, to the authors' knowledge, there is currently no consensus on the type of performance-oriented leaching test that can easily be used with mineral water to obtain useful insights into water-induced cementitious material degradation.…”

Section: Introductionmentioning

confidence: 99%

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Experimental Investigation on the Effects of Mineral Water Composition on the Leaching of Cement-Based Materials

Pouyanne,

Boudache,

Hilloulin

et al. 2024

Materials

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The common phenomenon observed for concrete in aggressive water is leaching, which involves the dissolution of cement hydration products. Many studies have focused on leaching in demineralised water or acid attacks, but mineral water still deserves further investigation. In most standards, the aggressiveness of a given water body is determined by its pH and not its composition. The effect of the calcium content of the water on degradation is yet to be determined. In this paper, the leaching of Portland cement-based mortar was induced by two types of drinking water with different calcium contents and buffer capacity in controlled conditions. The Langelier saturation index (LSI) was used to describe water aggressiveness based on the calco-carbonic equilibrium. The studied waters had the same pH but LSIs of +0.5 and −1.0 corresponding to scaling with respect to aggressive water; demineralised water was used as a reference. Microstructural damage was checked by TGA and X-ray microtomography. Macroscopic measurements were used to monitor global degradation. The soft water caused a 53% deeper deterioration of the mortar sample than the hard water. Soft water-induced leaching was found to be similar yet slower to leaching via demineralised water (with a mass loss of −2.01% and −2.16% after 200 days, respectively). In contrast, hard water induced strongly time-dependent leaching, and the damage was located close to the surface. The roughness of leached specimens was 18% higher in hard water than in soft water. The formation of calcite on the sample surface not only affects the leaching rate by creating a protective surface layer, but it could also act as a calcium ion pump.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Experimental Investigation on the Effects of Mineral Water Composition on the Leaching of Cement-Based Materials

Pouyanne,

Boudache,

Hilloulin

et al. 2024

Materials

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“…During the dissolution process, the primary hydration products in concrete (i.e., calcium hydroxide (CH) and hydrated calcium silicate (C-S-H) gel) undergo decomposition and precipitation [12,13], resulting in an increase in material porosity, permeability, and diffusivity [14][15][16][17]. In contrast to traditional contact dissolution, the driving force for the leaching of calcium in concrete impermeable structures includes not only concentration gradients but also hydraulic gradients, and the seepage driven by hydraulic gradients can accelerate the dissolution of hydration products [18]. Numerous hydraulic concrete structures worldwide are currently experiencing damage from seepage dissolution.…”

Section: Introductionmentioning

confidence: 99%

Durability Analysis of Concrete Cutoff Wall of Earth-Rock Dams Considering Seepage and Dissolution Coupling Effect

Guo,

Lu,

Song

et al. 2024

Water

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In this paper, a novel numerical model for characterizing the seepage and dissolution coupling effect on the durability of anti-seepage walls of earth-rock dams is proposed. The model considers the influence of hydraulic gradient-driven seepage on the non-equilibrium decomposition of the calcium dissolution in concrete, as well as the effects of seepage dissolution on pore structure, permeability, and diffusivity. The reasonableness of the model is validated by experimental and literature data, which is then applied to analyze the deterioration and failure processes of a concrete cutoff wall of an earth-rock dam in Zhejiang Province, China. On this basis, the seepage dissolution durability control indices of anti-seepage walls are identified. The findings demonstrate that the suggested method accurately explains the calcium leaching process in concrete. Under the seepage and dissolution coupling effect, calcium in the wall continuously decomposes and precipitates, leading to varying degrees of increases in structural performance parameters, which weaken the seepage control performance of the walls and consequently result in an increase in seepage discharge and hydraulic gradient. By proposing the critical hydraulic gradient as a criterion, the service life of the wall is projected to be 42.8 years. Additionally, the upstream hydraulic head, the initial permeability coefficient, and the calcium hydroxide (CH) content are three crucial indices affecting the durability of walls, and these indices should be reasonably controlled during the engineering design, construction, and operational phases.

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“…Nesse sentido, Neumann (2019) avaliou o processo de lixiviação no concreto de enchimento da casa de força da Usina Hidrelétrica de Itaipu constatando que entre 1984 e 2019 3,4% do total de cálcio existente na região passível de ser afetada havia sido perdido, valor considerado dentro dos limites estabelecidos durante a fase de concepção e projeto. Além disso, é importante ressaltar que o concreto desse local foi fabricado com a adição de cinza volante, conferindo pozolanicidade à mistura e, teoricamente, proporciona a mesma uma estrutura de poros mais refinada, podendo essa ser uma das razões para a boa resistência à lixiviação (C. Neumann et al, 2021). Dessa maneira, a fim de contribuir no entendimento do processo de lixiviação, essa pesquisa teve como objetivo avaliar o processo de lixiviação acelerada em três cimentos brasileiros, sendo dois deles compostos por MCS de origens pozolânicas e outro apenas com a adição de filler calcário.…”

Section: Introductionunclassified

Caracterização do comportamento de pastas e argamassas de cimentos Portland durante o processo de lixiviação acelerada

Goulart¹,

Dias²,

Santos³

2021

Congreso Latino-Americano De Patología De Construcción

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Este artigo tem o objetivo de analisar o comportamento de cimentos com adições frente ao processo de lixiviação acelerada de pastas e argamassas fabricadas a partir de três cimentos brasileiros, estas foram expostas a uma solução agressiva de nitrato de amônio que potencializa a dissolução dos íons de cálcio, sendo realizados ensaios de compressão axial, termogravimetria, DRX, titulação química e avanço da lixiviação. Os resultados obtidos indicaram um melhor comportamento dos cimentos pozolânicos frente ao processo de lixiviação, apresentando menor queda de resistência à compressão Axial, menor avanço da frente de lixiviação e maior estabilidade da portlandita. Análises complementares estão sendo realizadas a fim de compreender a influência da relação Ca/Si na lixiviação dos C-S-H.

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Concrete leaching of a hydroelectric powerhouse due to 40 years of exposure to river water

Cited by 23 publications

References 17 publications

Experimental Investigation on the Effects of Mineral Water Composition on the Leaching of Cement-Based Materials

Experimental Investigation on the Effects of Mineral Water Composition on the Leaching of Cement-Based Materials

Durability Analysis of Concrete Cutoff Wall of Earth-Rock Dams Considering Seepage and Dissolution Coupling Effect

Caracterização do comportamento de pastas e argamassas de cimentos Portland durante o processo de lixiviação acelerada

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