Chloride Penetration into Concrete under the Coupling Effects of Internal and External Relative Humidity

Fang, Zhu; Ma, Zhiming; Ming-min, Zhang

doi:10.1155/2020/1468717

Cited by 4 publications

(4 citation statements)

References 41 publications

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“…Reinforced concrete structures are very vulnerable to chloride ion ingress, which can result in steel corrosion [ 104 ]. When steel bars corrode due to chloride-induced corrosion, it weakens the structure’s strength and safety by causing spalling and reducing the steel cross-sectional area.…”

Section: Chloride Ion Penetration Of Concrete Enhanced With Nanomater...mentioning

confidence: 99%

An Elucidative Review of the Nanomaterial Effect on the Durability and Calcium-Silicate-Hydrate (C-S-H) Gel Development of Concrete

Al-saffar,

Wong,

Paul

2023

Gels

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Concrete as a building material is susceptible to degradation by environmental threats such as thermal diffusion, acid and sulphate infiltration, and chloride penetration. Hence, the inclusion of nanomaterials in concrete has a positive effect in terms of promoting its mechanical strength and durability performance, as well as resulting in energy savings due to reduced cement consumption in concrete production. This review article discussed the novel advances in research regarding C-S-H gel promotion and concrete durability improvement using nanomaterials. Basically, this review deals with topics relevant to the influence of nanomaterials on concrete’s resistance to heat, acid, sulphate, chlorides, and wear deterioration, as well as the impact on concrete microstructure and chemical bonding. The significance of this review is a critical discussion on the cementation mechanism of nanoparticles in enhancing durability properties owing to their nanofiller effect, pozzolanic reactivity, and nucleation effect. The utilization of nanoparticles enhanced the hydrolysis of cement, leading to a rise in the production of C-S-H gel. Consequently, this improvement in concrete microstructure led to a reduction in the number of capillary pores and pore connectivity, thereby improving the concrete’s water resistance. Microstructural and chemical evidence obtained using SEM and XRD indicated that nanomaterials facilitated the formation of cement gel either by reacting pozzolanically with portlandite to generate more C-S-H gel or by functioning as nucleation sites. Due to an increased rate of C-S-H gel formation, concrete enhanced with nanoparticles exhibited greater durability against heat damage, external attack by acids and sulphates, chloride diffusion, and surface abrasion. The durability improvement following nanomaterial incorporation into concrete can be summarised as enhanced residual mechanical strength, reduced concrete mass loss, reduced diffusion coefficients for thermal and chloride, improved performance against sulphates and acid attack, and increased surface resistance to abrasion.

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Section: Chloride Ion Penetration Of Concrete Enhanced With Nanomater...mentioning

confidence: 99%

An Elucidative Review of the Nanomaterial Effect on the Durability and Calcium-Silicate-Hydrate (C-S-H) Gel Development of Concrete

Al-saffar,

Wong,

Paul

2023

Gels

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“…Figure 5 shows the chloride diffusion coefficient over time. Assuming that t 1 is 20 d, the relative ratio of the chloride diffusion coefficient is averaged under three temperatures for 20 d, 40 d, and 60 d. Equation (15) was fitted to determine the empirical coefficient α of 0.65.…”

Section: Effect Of Time On Chloride Diffusion Coefficientmentioning

confidence: 99%

“…Combining equations ( 14), (15), and ( 28), the equation of chloride diffusion coefficient in unsaturated concrete can be established:…”

Section: Chloride Transport Modelmentioning

confidence: 99%

“…e study performed by Zhang et al [14] confirmed that RH played an important role in the chloride diffusion coefficient; that is, the chloride diffusion coefficient increased with RH increasing. Zhu et al [15] explored the effect of environmental RH on the permeability of chloride in unsaturated concrete. e results showed that when RH was greater than 75%, the content of chloride in concrete increased gradually, while the content of chloride on the surface decreased gradually over time.…”

Section: Introductionmentioning

confidence: 99%

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Investigation on Numerical Simulation of Chloride Transport in Unsaturated Concrete

Zhang

Wang

Ling

et al. 2021

Advances in Materials Science and Engineering

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Marine atmosphere environment accelerates the process of chloride penetration into concrete under the coupling effect of ambient temperature and relative humidity, thereby reducing the durability and service life of concrete. This paper aims to investigate the change of water equilibrium saturation and the chloride transport properties of concrete materials in different environments. The water equilibrium saturation tests at three temperatures and five relative humidity (RH) and salt spray erosion tests at three temperatures were performed. The influence of RH and temperature on the equilibrium saturation of concrete and the influence of temperature and time on the chloride diffusion coefficient are investigated. The results show that, in the process of moisture absorption and desorption, the equilibrium saturation of concrete gradually decreases as temperature rises. At the same depth of concrete, the chloride content gradually increases with temperature increasing, as well as the chloride diffusion coefficient. However, as the corrosion time of salt spray increases, the altering of chloride diffusion coefficient becomes less. Based on the Kelvin equation, a relationship between capillary pressure and water saturation in concrete was established, and a moisture transfer model for concrete in the process of moisture absorption and desorption was derived. Further, based on the established chloride diffusion equation and heat balance equation, a model of temperature-wet-chloride coupling chloride transfer was derived. Theory model simulation results show the transfer speed of chloride under the coupling of diffusion and capillary is higher than pure diffusion in moisture in the absorption process. However, the opposite is true in the desorption process. Moreover, with the increment of saturation rate, the capillary effect on chloride transport is enhanced.

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Early‐age behavior and mechanical properties of cement‐based materials with various types and fineness of recycled powder

Liang

et al. 2021

Structural Concrete

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Recycled powder (RP) that includes recycled paste powder (RPP), recycled mortar powder (RMP), and recycled concrete powder (RCP) is an eco-friendly alternative binder. This work investigated the influence of RP types and fineness on early-age behavior and mechanical strength of cement-based materials. The results show that substituting RP for cement causes the reduction of new hydration products in cement-based materials. The blended RP decreases the fluidity of paste mixture, and the fluidity of paste including fine RPP is lower than that of paste including fine RMP and RCP; moreover, the fluidity increases following the growth of RP particle size. Incorporating fine RPP

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Chloride Penetration into Concrete under the Coupling Effects of Internal and External Relative Humidity

Cited by 4 publications

References 41 publications

An Elucidative Review of the Nanomaterial Effect on the Durability and Calcium-Silicate-Hydrate (C-S-H) Gel Development of Concrete

An Elucidative Review of the Nanomaterial Effect on the Durability and Calcium-Silicate-Hydrate (C-S-H) Gel Development of Concrete

Investigation on Numerical Simulation of Chloride Transport in Unsaturated Concrete

Early‐age behavior and mechanical properties of cement‐based materials with various types and fineness of recycled powder

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