Reinforcement corrosion and transport of water and chloride ions in shrinkage-compensating cement concretes

Shi, Weizhuo; Najimi, Meysam; Shafei, Behrouz

doi:10.1016/j.cemconres.2020.106121

Cited by 39 publications

(12 citation statements)

References 23 publications

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“…Among them, the expansion rate of CMM0-12 h is −0.2735% (the crack is circled in red in Figure 9) because of thermal expansion and cold contraction of cement hydration. This result is consistent with the results of Shi [35]. The expansion rates of CMM4-12 h and CMM5-12 h are 0.8916% and 1.3667%, respectively, which are higher than the standard value (0.5%) of GB/T 750-1992.…”

Section: Volume Stabilitysupporting

confidence: 92%

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Circulating Fluidized Bed Fly Ash Mixed Functional Cementitious Materials: Shrinkage Compensation of f-CaO, Autoclaved Hydration Characteristics and Environmental Performance

et al. 2021

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Circulating fluidized bed (CFB) fly ash is a by-product from CFB power generation, which is hard to utilize in cement because it contains f-CaO and SO3. This work aims to explore the mechanism of the shrinkage compensation of free-CaO (f-CaO) and the autoclaved hydration characteristics and environmental performance of CFB fly ash mixed cementitious materials (CMM). In this work, long-term volume stability of CMM is improved with the addition of CFBFA. These findings suggest that the compressive strength of sample CMM0.5 is the highest under both standard condition (67.21 MPa) and autoclaved condition (89.56 MPa). Meanwhile, the expansion rate (0.0207%) of sample CMM0.5 is the lowest, which proves the shrinkage compensation effect of f-CaO in CFBFA. The main hydration products of CMM0.5 are Ca2SiO4•H2O (C-S-H) gel, CaAl2Si2O7(OH)2•H2O (C-A-S-H) gel and Ca(OH)2. In addition, the high polymerization degree of [Si(Al)O4] and the densified microstructure are presented at the sample CMM0.5. The leaching results indicates that the heavy metals in CMM0.5 satisfies the WHO standards for drinking water due to physical encapsulation and charge balance. Therefore, this investigation provides a novel method of using CFB fly ash in cement.

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Section: Volume Stabilitysupporting

confidence: 92%

“…The volume shrinkage of cement leads to cracking in late hydration [35]. Furthermore, magnetization, freeze-thaw, harmful ion reactions and reinforcement corrosion hazards are easily caused due to cement cracking [36].…”

Section: Volume Stabilitymentioning

confidence: 99%

Circulating Fluidized Bed Fly Ash Mixed Functional Cementitious Materials: Shrinkage Compensation of f-CaO, Autoclaved Hydration Characteristics and Environmental Performance

et al. 2021

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“…The formation of cracks expedites the transport of corrosive agents, mainly chloride ions and CO 2 , into concrete, endangering the durability of reinforced concrete structures [ 193 , 194 , 195 , 196 , 197 ]. Several methods have been suggested to help concrete withstand shrinkage-induced cracks, including the use of shrinkage-compensating cement [ 198 , 199 , 200 ] and/or fibers. When fibers are incorporated into a concrete mixture, even in low dosages, they can withstand the induced tensile stresses, preventing the formation of cracks that can endanger the life-cycle performance and durability of concrete structures.…”

Section: Shrinkagementioning

confidence: 99%

State-of-the-Art Review of Capabilities and Limitations of Polymer and Glass Fibers Used for Fiber-Reinforced Concrete

et al. 2021

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The concrete industry has long been adding discrete fibers to cementitious materials to compensate for their (relatively) low tensile strengths and control possible cracks. Extensive past studies have identified effective strategies to mix and utilize the discrete fibers, but as the fiber material properties advance, so do the properties of the cementitious composites made with them. Thus, it is critical to have a state-of-the-art understanding of not only the effects of individual fiber types on various properties of concrete, but also how those properties are influenced by changing the fiber type. For this purpose, the current study provides a detailed review of the relevant literature pertaining to different fiber types considered for fiber-reinforced concrete (FRC) applications with a focus on their capabilities, limitations, common uses, and most recent advances. To achieve this goal, the main fiber properties that are influential on the characteristics of cementitious composites in the fresh and hardened states are first investigated. The study is then extended to the stability of the identified fibers in alkaline environments and how they bond with cementitious matrices. The effects of fiber type on the workability, pre- and post-peak mechanical properties, shrinkage, and extreme temperature resistance of the FRC are explored as well. In offering holistic comparisons, the outcome of this study provides a comprehensive guide to properly choose and utilize the benefits of fibers in concrete, facilitating an informed design of various FRC products.

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“…Chlorides from de-icing salts cause corrosion of steel reinforcements and destruction of concrete in a dry climate when they crystallize and cause stress on pores in concrete [88][89][90][91][92][93]. According to [94], the chloride content in concrete is related to the mass of the cement and should not exceed 1% (when there are no metal elements), 0.20% or 0.40% (concrete with reinforcement and metal elements), and 0.20% (steel prestressing reinforcements).…”

Section: Free Chlorides Contentmentioning

confidence: 99%

Concrete Examination of 100-Year-Old Bridge Structure above the Kłodnica River Flowing through the Agglomeration of Upper Silesia in Gliwice: A Case Study

et al. 2021

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The article analyzes the composition of concrete taken from various elements from a 100-year-old bridge in South Poland, so as to analyze its technical condition. The main methods applied during experimental work were: Designation of pH, free chloride content, salinity, XRD and SEM examinations, as well as metals determination using inductively coupled plasma mass spectrometry (ICPMS), high-performance liquid chromatography (HPLC)-ICP-MS, and cold-vapor atomic absorption spectroscopy (CV-AAS). The concrete of the bridge was strongly carbonated and decalcified with an extremely high content of chlorides. The pH of the concrete was in a range from 10.5 to 12.0. Acid soluble components were between 9.9% and 17.6%. Typical sulfate corrosion phases of concrete were not detected. Friedels’ salt was found only at the extremity of an arch. The crown block was corroded to the greatest extent. Various heavy metals were absorbed into the concrete, likely from previous centuries, when environmental protection policy was poor. The applied research methodology can be used on bridges exposed to specific external influences. The acquired knowledge can be useful in the management processes of the bridge infrastructure. It can help in making decisions about decommissioning or extending the life cycle of the bridge. This work should also sensitize researchers and decision-makers to the context of “bridge safety”.

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Reinforcement corrosion and transport of water and chloride ions in shrinkage-compensating cement concretes

Cited by 39 publications

References 23 publications

Circulating Fluidized Bed Fly Ash Mixed Functional Cementitious Materials: Shrinkage Compensation of f-CaO, Autoclaved Hydration Characteristics and Environmental Performance

Circulating Fluidized Bed Fly Ash Mixed Functional Cementitious Materials: Shrinkage Compensation of f-CaO, Autoclaved Hydration Characteristics and Environmental Performance

State-of-the-Art Review of Capabilities and Limitations of Polymer and Glass Fibers Used for Fiber-Reinforced Concrete

Concrete Examination of 100-Year-Old Bridge Structure above the Kłodnica River Flowing through the Agglomeration of Upper Silesia in Gliwice: A Case Study

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