Calcium leaching from cement hydrates exposed to sodium sulfate solutions

Zou, Dujian; Zhang, Ming; Qin, Shanshan; Liu, Tiejun; Tong, Wenhao; Zhou, Ao; Jivkov, Andrey P.

doi:10.1016/j.conbuildmat.2022.128975

Cited by 24 publications

(5 citation statements)

References 51 publications

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“…Tang et al [61] investigated the impact of calcium leaching on chloride diffusivities and they reported that the calcium leaching not only result in higher chloride diffusion rate but also reduce the chloride binding capacity. Recently, Zou et al [62] both experimentally and numerically studied concrete leaching phenomenon when exposed to sulfate rich environments. It showed that sulfate ions could accelerate the leaching process of calcium.…”

Section: Coupled Deterioration Of Calcium Leaching and Chloride Ingressmentioning

confidence: 99%

Progress and research challenges in concrete durability: ionic transport, electrochemical rehabilitation and service life prediction

2022

RILEM Tech Lett

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Concrete durability degradation problems have received considerable attention in both research field and concrete industry during recent decades. To better understand the underlying mechanisms, various numerical models have been put forward aiming at widely concerned scientific issues involved in the entire life cycle of concrete structures: ionic transport in porous medium, degradations induced by multiple factors, as well as the prediction and rehabilitation method to prolong the service life. This letter aims to summarise the major contributions to these interrelated scientific issues particularly from the modelling perspective. The digital characterization of concrete heterogeneity and its influence on ionic transport behaviour will be firstly reviewed. Subsequently, concrete deterioration mechanisms induced by various factors and their internal coupling relationships are discussed in details. Meanwhile, promising electrochemical repair techniques with multi-fold advantages including chloride removal, corrosion inhibition, ASR mitigation and crack repair are systematically summarized. Finally, existing research gaps and future opportunities in these areas have also been visited, which is hoped to break the ice in this challenging field and promote the sustainable development of the concrete industry.

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Section: Coupled Deterioration Of Calcium Leaching and Chloride Ingressmentioning

confidence: 99%

Progress and research challenges in concrete durability: ionic transport, electrochemical rehabilitation and service life prediction

2022

RILEM Tech Lett

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“…At present, numerous scholars have conducted experiments and numerical simulations regarding the durability issues associated with concrete calcium leaching [23][24][25][26][27][28][29]. These studies not only reveal the response mechanisms of concrete calcium leaching degradation processes to various factors but also provide numerous solutions for the management of concrete calcium leaching degradation.…”

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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“…For example, the leaching process changes the pH of the immersion solution from neutral to about 12.5 (equilibrium pH of the pore solution). These later exposure conditions are therefore less severe for the samples and lengthen the duration of the test in comparison to a test that maintains the concentration over time [ 27 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 ]. Furthermore, the change in the exposure conditions does not represent the in-situ reality when it is considered that the reactants are inexhaustible and always accessible.…”

Section: Introductionmentioning

confidence: 99%

A Critical Review of Existing Test-Methods for External Sulfate Attack

et al. 2022

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External sulfate attack (ESA) of cementitious materials has been studied worldwide for a very long time. This physical/chemical interaction between sulfate ions and the cement hardened elements affects the long-term durability of concrete structures: cracking, spalling or strength loss of concrete structures. To study these damaging phenomena, some standardized and non-standardized accelerated aging tests are used to evaluate the performance of cements in sulfate-rich environments. However, these existing methods do not adequately predict field performance and some shortcomings or deficiencies still exist: change of degradation mechanisms when using high concentrations of sulfate, variable boundary conditions and small specimens compared to the real concrete structures. In this work, a critical review of some existing test methods and foreign national standard methods for ESA are presented, analyzed, and discussed. This results in some proposed recommendations for improving these methods to meet the needs of structure managers.

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Calcium leaching from cement hydrates exposed to sodium sulfate solutions

Cited by 24 publications

References 51 publications

Progress and research challenges in concrete durability: ionic transport, electrochemical rehabilitation and service life prediction

Progress and research challenges in concrete durability: ionic transport, electrochemical rehabilitation and service life prediction

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

A Critical Review of Existing Test-Methods for External Sulfate Attack

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