Special Issue "Corrosion, Properties and Characterization in Concrete"

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Construction and Building Materials".

Deadline for manuscript submissions: 20 February 2022.

Special Issue Editors

Prof. Dr. Lihai Zhang
E-Mail Website
Guest Editor
Department of Infrastructure Engineering, The University of Melbourne, Parkville, VIC 3010, Australia
Interests: concrete corrosion; reactive transport of sulfate and chloride ions in concrete; performance assessment of glass and aluminum cladding against hail storms; engineering reliability; machine learning
Dr. Kai Wu
E-Mail Website
Guest Editor
School of Materials Science and Engineering, Tongji University, Shanghai 201804, China
Interests: concrete durability; functional materials; multi-scale determination

Special Issue Information

Dear Colleagues,

Due to the low cost, ready availability, and comprehensive performance of raw materials, concrete has been widely used in the construction of engineering structures for many decades. However, the durability of reinforced concrete (RC) structures could be significantly compromised under extreme environmental conditions, such as sulfate and chlorine ion attack in a marine environment. As the deterioration of concrete could lead to the significant reduction in the service life of RC structures, and the ultimately the potential loss of billions of dollars, the fundamental understanding of corrosion, properties and characterization in concrete becomes increasingly important. With the development of microscopic new techniques in material science in last decade, significant advances have been made in capturing the change in the microstructure of concrete at different degrading stages under various environmental conditions. In addition, the development of modern concrete using supplementary cementitious materials (e.g., fly ash and slag) and the application of advanced 3D printing and nanotechnology represent the direction of future concrete development. This Special Issue contributes to a useful reference for further research and development of new advanced concrete technology to prolong the service-life of concrete structures.

Prof. Dr. Lihai Zhang
Dr. Kai Wu
Guest Editors

Manuscript Submission Information

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Keywords

  • concrete
  • corrosion
  • microstructure
  • fly ash and slag
  • nanotechnology
  • 3D printing
  • microscopy

Published Papers (7 papers)

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Research

Article
Influence of Mineral Additives on the Efflorescence of Ettringite-Rich Systems
Materials 2021, 14(18), 5464; https://doi.org/10.3390/ma14185464 (registering DOI) - 21 Sep 2021
Abstract
Efflorescence is aesthetically undesirable to all cementitious materials products and mainly results from the carbonation of hydrates and salt precipitation. Alternative binders without portlandite formation theoretically have much lower efflorescence risk, but in practice, the efflorescence of ettringite-rich systems is still serious. This [...] Read more.
Efflorescence is aesthetically undesirable to all cementitious materials products and mainly results from the carbonation of hydrates and salt precipitation. Alternative binders without portlandite formation theoretically have much lower efflorescence risk, but in practice, the efflorescence of ettringite-rich systems is still serious. This study reports the impacts of mineral additives on the efflorescence of ettringite-rich systems and the corresponding microstructural evolution. The effects of silica fume, limestone powder, and diatomite on efflorescence and the capillary pore structure of mortars were investigated from a multi-scale analysis. The composition and microstructure of efflorescent phases were revealed by optical microscope (O.M.), in-situ Raman spectroscopy, and Scanning Electron Microscopy (SEM). Results indicate that the addition of mineral additives can efficiently inhibit the efflorescence of reference, especially with silica fume. Similar to the ettringite-rich system, the efflorescence substances of all modifies are composed of ettringite and CaCO3, indicating that the addition of mineral admixture does not lead to chemical reactions, lower capillary absorption coefficient of mineral additives modified specimen, the denser pore structure and the lower efflorescence degree. Full article
(This article belongs to the Special Issue Corrosion, Properties and Characterization in Concrete)
Article
The Failure Mechanisms of Precast Geopolymer after Water Immersion
Materials 2021, 14(18), 5299; https://doi.org/10.3390/ma14185299 - 14 Sep 2021
Viewed by 375
Abstract
Precast geopolymers with lower water/binder (0.14), which mainly consists of alkali solution, fly ash (FA) and steel slag (SS), were manufactured through molding pressing technology. The failure mechanisms of precast geopolymers after water immersion were studied by testing the loss of compressive strength, [...] Read more.
Precast geopolymers with lower water/binder (0.14), which mainly consists of alkali solution, fly ash (FA) and steel slag (SS), were manufactured through molding pressing technology. The failure mechanisms of precast geopolymers after water immersion were studied by testing the loss of compressive strength, the pH of the leaching solution, the concentration of ions (Na+, Ca2+, Si4+ and Al3+), the evolution of phases, pore structure and morphology, and further discussion of the regulation evolution was performed. The results show that the harmful pores (>50 nm) of geopolymers progressively decrease from 70% to 50% after 28 days of water immersion when the content of steel slag increases from 0 to 80 wt.%. Compressive strength of geopolymers sharply reduces in the first 3 days and then increases during the water immersion process, but the phase composition varies slightly. Furthermore, increasing the content of steel slag could decrease the total porosity and further prevent the water resistance. Full article
(This article belongs to the Special Issue Corrosion, Properties and Characterization in Concrete)
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Article
Identification of Chemical Bonds and Microstructure of Hydrated Tricalcium Silicate (C3S) by a Coupled Micro-Raman/BSE-EDS Evaluation
Materials 2021, 14(18), 5144; https://doi.org/10.3390/ma14185144 - 08 Sep 2021
Viewed by 450
Abstract
Identifying the phase evolution and revealing the chemical bonds of hydrated cements accurately is crucial to regulate the performance of cementitious materials. In this paper, a coupled Raman/BSE-EDS analysis was proposed to determine the chemical bonds of tricalcium silicate hydrates and the interface [...] Read more.
Identifying the phase evolution and revealing the chemical bonds of hydrated cements accurately is crucial to regulate the performance of cementitious materials. In this paper, a coupled Raman/BSE-EDS analysis was proposed to determine the chemical bonds of tricalcium silicate hydrates and the interface transition zone (ITZ) between inner C-S-H and anhydrates. The results show that the Raman/BSE-EDS method can accurately identify the chemical bonds of inner C-S-H and inner ITZ regions, which confirms the mixed structure of inner C-S-H and nano calcium hydroxide (CH). The inner ITZ shows a lattice change region with a thickness of 700–1000 nm, which can be attributed to the pre-disassembly process of C3S crystal. The successful application of coupled Raman/BSE-EDS provides new insight into the hydration process and multi-structure features of traditional cementitious materials. Full article
(This article belongs to the Special Issue Corrosion, Properties and Characterization in Concrete)
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Article
A Comprehensive Study on the Hardening Features and Performance of Self-Compacting Concrete with High-Volume Fly Ash and Slag
Materials 2021, 14(15), 4286; https://doi.org/10.3390/ma14154286 - 31 Jul 2021
Viewed by 377
Abstract
The main concern of this work is to evaluate the influences of supplementary cementitious materials (fly ash, slag) and a new type of polycarboxylate superplasticizer containing viscosity modifying agents (PCE-VMA) on the performance of self-compacting concrete (SCC). The workability, hydration process, mechanical property, [...] Read more.
The main concern of this work is to evaluate the influences of supplementary cementitious materials (fly ash, slag) and a new type of polycarboxylate superplasticizer containing viscosity modifying agents (PCE-VMA) on the performance of self-compacting concrete (SCC). The workability, hydration process, mechanical property, chloride permeability, degree of hydration and pore structure of SCC were investigated. Results indicate that the addition of fly ash and slag slows down early hydration and decreases the hydration degree of SCC, and thus leads to a decline in compressive strengths, especially within the first 7 days. The addition of slag refines pore structure and contributes to lower porosity, and thus the chloride permeability of SCC is decreased during the late hydration stage. Additionally, a new factor of calculated water–binder ratio is put forward, which can directly reflect the free water content of concrete mixture after mixing, and guide the mix proportion design of SCC. Full article
(This article belongs to the Special Issue Corrosion, Properties and Characterization in Concrete)
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Article
Steel Corrosion Behavior of Reinforced Calcium Aluminate Cement-Mineral Additions Modified Mortar
Materials 2021, 14(14), 4053; https://doi.org/10.3390/ma14144053 - 20 Jul 2021
Cited by 1 | Viewed by 464
Abstract
Mineral additions can eliminate the conversion in calcium aluminate hydrates and thus inhibit the future strength retraction of calcium aluminate cement (CAC). However, the impacts of these additions on the protection capacity of CAC concrete in relation to the corrosion of embedded steel [...] Read more.
Mineral additions can eliminate the conversion in calcium aluminate hydrates and thus inhibit the future strength retraction of calcium aluminate cement (CAC). However, the impacts of these additions on the protection capacity of CAC concrete in relation to the corrosion of embedded steel reinforcement remains unclear. This paper focused on the corrosion behavior of steel reinforcement in slag, limestone powder, or calcium nitrate-modified CAC mortars via XRD and electrochemical methods (corrosion potential, electrochemical impedance, and linear polarization evaluation). The results indicate that strätlingite (C2ASH8), which is formed in slag-modified CAC, has poor chloride-binding ability, leading to decline in corrosion resistance of the steel reinforcement. The electrochemical parameters of specimens immersed in NaCl solution suddenly drop at 14 days, which is 28 days earlier than that of the references. In contrast, the Ca2[Al(OH)6]20.5CO3OH·H2O (CaAl·CO32−-LDH) and 3CaO·Al2O3·Ca(NO3)2·12H2O (NO3-AFm) in limestone powder and calcium nitrate-modified CAC mortar show great chloride-binding ability, thereby improving the corrosion resistance of the steel reinforcement. The electrochemical parameters of specimens modified with calcium nitrate maintain a slow decreasing trend within 90 days. Full article
(This article belongs to the Special Issue Corrosion, Properties and Characterization in Concrete)
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Article
Impacts of Space Restriction on the Microstructure of Calcium Silicate Hydrate
Materials 2021, 14(13), 3645; https://doi.org/10.3390/ma14133645 - 30 Jun 2021
Cited by 1 | Viewed by 358
Abstract
The effect of hydration space on cement hydration is essential. After a few days, space restriction affects the hydration kinetics which dominate the expansion, shrinkage and creep of cement materials. The influence of space restriction on the hydration products of tricalcium silicate was [...] Read more.
The effect of hydration space on cement hydration is essential. After a few days, space restriction affects the hydration kinetics which dominate the expansion, shrinkage and creep of cement materials. The influence of space restriction on the hydration products of tricalcium silicate was studied in this paper. The microstructure, morphology and composition of calcium silicate hydrate (C-S-H) were explored from the perspective of a specific single micropore. A combination of Raman spectra, Fourier transform infrared spectra, scanning electron microscopy and energy dispersive X-ray spectroscopy were employed. The results show that space restriction affects the structure of the hydration products. The C-S-H formed in the micropores was mainly composed of Q3 silicate tetrahedra with a high degree of polymerization. The C-S-H formed under standard conditions with a water to cement ratio of 0.5 mostly existed as Q2 units. Space restriction during hydration is conducive to the formation of C-S-H with silica tetrahedra of a high polymerization degree, while the amount of water filling the micropore plays no obvious role on the polymeric structure of C-S-H during hydration. Full article
(This article belongs to the Special Issue Corrosion, Properties and Characterization in Concrete)
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Article
Cyclic Behavior of Reinforced High Strain-Hardening UHPC under Axial Tension
Materials 2021, 14(13), 3602; https://doi.org/10.3390/ma14133602 - 28 Jun 2021
Viewed by 350
Abstract
The cyclic tensile behavior of steel-reinforced high strain-hardening ultrahigh-performance concrete (HSHUHPC) was investigated in this paper. In the experimental program, 12 HSHUHPC specimens concentrically placed in a single steel reinforcement under cyclic uniaxial tension were tested, accompanied by acoustic emission (AE) source locating [...] Read more.
The cyclic tensile behavior of steel-reinforced high strain-hardening ultrahigh-performance concrete (HSHUHPC) was investigated in this paper. In the experimental program, 12 HSHUHPC specimens concentrically placed in a single steel reinforcement under cyclic uniaxial tension were tested, accompanied by acoustic emission (AE) source locating technology, and 4 identical specimens under monotonic uniaxial tension were tested as references. The experimental variables mainly include the loading pattern, the diameter of the embedded steel rebar, and the level of target strain at each cycle. The tensile responses of the steel-reinforced HSHUHPC specimens were evaluated using multiple performance measures, including the failure pattern, load–strain response, residual strain, stiffness degradation, and the tension-stiffening behavior. The test results showed that the enhanced bond strength due to the inclusion of steel fibers transformed the failure pattern of the steel-reinforced HSHUHPC into a single, localized macro-crack in conjunction with a sprinkling of narrow and closely spaced micro-cracks, which intensified the strain concentration in the embedded steel rebar. Besides, it was observed that the larger the diameter of the embedded steel rebar, the smaller the maximum accumulative tensile strain under cyclic tension, which indicated that the larger the diameter of the embedded steel rebar, the greater the contribution to the tensile stiffness of steel-reinforced HSHUHPC specimens in the elastic–plastic stage. In addition, it was found that a larger embedded steel rebar appeared to reduce the tension-stiffening effect (peak tensile strength) of the HSHUHPC. Moreover, the residual strain and the stiffness of the steel-reinforced HSHUHPC were reduced by increasing the number of cycles and finally tended toward stability. Nevertheless, different target strain rates in each cycle resulted in different eventual cumulative tensile strain rates; hence the rules about failure pattern, residual strain, and loading stiffness were divergent. Finally, the relationship between the accumulative tensile strain and the loading stiffness degradation ratio under cyclic tension was proposed and the tension-stiffening effect was analyzed. Full article
(This article belongs to the Special Issue Corrosion, Properties and Characterization in Concrete)
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