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Development and Characterization of New Construction Materials and Coatings
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Development and Characterization of New Construction Materials and Coatings

A special issue of Coatings (ISSN 2079-6412). This special issue belongs to the section "Corrosion, Wear and Erosion".

Deadline for manuscript submissions: 31 October 2024 | Viewed by 9729

Special Issue Editor

Dr. Fujian Tang

E-Mail Website
Guest Editor
School of Civil Engineering, Dalian University of Technology, Dalian 116024, China
Interests: concrete durability; reinforcement steel corrosion and prevention; coating and construction materials; sensors and structural health monitoring; safety and life-cycle assessment
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The Special Issue, titled "Development and Characterization of New Construction Materials and Coatings", showcases the latest advancements in the field of construction materials and coatings. With a focus on innovation and characterization, this issue explores the development of new materials and coatings that offer improved performance, sustainability, and durability for the construction industry.

Construction materials play a pivotal role in ensuring the strength, safety, and longevity of civil infrastructure projects. This Special Issue presents a collection of research articles, reviews, and perspectives contributed by leading experts and researchers, covering various aspects related to the development and characterization of new construction materials and coatings.

Key areas covered in this Special Issue include:

  1. Novel material synthesis and design: Research on the development of innovative construction materials using novel synthesis techniques, including advanced composites, polymers, nano-materials, concrete mixes, and eco-friendly alternatives. These new materials strive to improve mechanical properties, sustainability, and efficiency.
  2. Characterization techniques and methodologies: Exploration of advanced characterization techniques such as microscopy, spectroscopy, thermal analysis, mechanical testing, and non-destructive evaluation methods. These studies aim to understand the structure–property relationships, performance, and behavior of new construction materials and coatings.
  3. Sustainable construction practices: Investigation into environmentally friendly materials and coatings that minimize environmental impact, reduce carbon emissions, promote energy efficiency, and incorporate recycled or renewable resources. These developments contribute to sustainable construction practices and support the goals of green building certifications.
  4. Performance evaluation and testing: Studies focusing on the performance evaluation and testing of newly developed materials and coatings. This includes assessing their mechanical strength, durability, fire resistance, corrosion resistance, weatherability, and other important performance characteristics to ensure their reliability in real-world applications.
  5. Innovative coating technologies: Research on the development of advanced coatings with improved properties such as adhesion, wear resistance, chemical resistance, and functional enhancements. These coatings provide protection, aesthetics, and extended service life to construction materials.
  6. Structural optimization and modeling: Utilization of computational modeling, simulation, and optimization techniques to design and analyze the behavior and performance of new construction materials and coatings. These tools aid in the development of efficient and cost-effective structural designs.

By highlighting the development and characterization of new construction materials and coatings, this Special Issue serves as a valuable resource for researchers, engineers, architects, and industry professionals involved in the construction sector. The findings presented pave the way for enhanced construction practices, increased sustainability, and improved infrastructure resilience. Ultimately, these advancements contribute to the advancement of the construction industry and the creation of more robust and sustainable built environments.

Dr. Fujian Tang
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Coatings is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • construction materials
  • coating technologies
  • sustainable construction
  • structural optimization
  • novel composites
  • eco-friendly alternatives
  • mechanical testing
  • fire resistance
  • corrosion resistance

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Published Papers (11 papers)

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Research

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15 pages, 4839 KiB  
Article
Research on the Corrosion Resistance of Reactive Powder Concrete with Straw Fibers under Chloride Environment
by An Wang, Weixiang Sun, Miao Lu, Xi Peng, Hui Wang and Yao Ji
Coatings 2024, 14(8), 961; https://doi.org/10.3390/coatings14080961 - 1 Aug 2024
Viewed by 382
Abstract
Reactive powder concrete (RPC) is widely used in large-scale bridges, and its durability in coastal areas has become a significant concern. Straw fibers have been evidenced to improve the mechanical properties of concrete, while research on their influence on the chloride corrosion resistance [...] Read more.
Reactive powder concrete (RPC) is widely used in large-scale bridges, and its durability in coastal areas has become a significant concern. Straw fibers have been evidenced to improve the mechanical properties of concrete, while research on their influence on the chloride corrosion resistance of RPC is deficient. Therefore, it is essential to establish the relationships between the quantities and parameters of straw fibers and the properties of the resulting concrete. In this study, the mass loss rates (MLRs), the relative dynamic modulus of elasticity (RDME), the electrical resistance (R), the AC impedance spectrum (ACIS), and the corrosion rates of steel-bar-reinforced RPC mixed with 0%–4% straw fibers by volume of RPC were investigated. A scanning electron microscope (SEM) and X-ray diffraction (XRD) were used to analyze the corrosion of steel bars. The reinforced RPC specimens were exposed to a 3% NaCl dry-wet alternations (D-As) and 3% NaCl freeze-thaw cycles (F-Cs) environment. The results show that, after adding 1%–4% straw fibers, the setting time and slump flow of fresh RPC were reduced by up to 16.92% and 12.89%. The MLRs were −0.44%–0.43% and −0.38%–0.42%, respectively, during the D-As and F-Cs. The relationship between the RDME and the fiber volume ratio was the quadratic function, and it was improved by 9.34%–13.94% and 3.01%–5.26% after 10 D-As and 100 F-Cs, respectively. Incorporating 4% straw fibers reduced the R values of the reinforced RPC specimens by up to 22.90% and decreased the corrosion rates after 10 D-As and 100 F-Cs by 26.08% and 82.29%, respectively. The impedance value was also increased. Moreover, a dense, ultra-fine iron layer and α-FeO(OH) were observed in the rust of rebars by SEM and XRD, as the corrosion resistance of rebars was enhanced. The results indicate that straw fibers improved the corrosion resistance of RPC, which can serve as a protective material to inhibit concrete cracking and thereby prevent rebar oxidation. This study provides theoretical support for the investigation of surface phenomena in reinforced RPC with straw fibers. Full article
(This article belongs to the Special Issue Development and Characterization of New Construction Materials and Coatings)
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12 pages, 4010 KiB  
Article
Effect of Mixing and Curing System on Carbon Fixation Amount and Performance of Circulating Fluidized Bed Fly Ash Cement Cementitious Material System
by Hao Zhang, Hui Li and Kai Wang
Coatings 2024, 14(8), 936; https://doi.org/10.3390/coatings14080936 - 26 Jul 2024
Viewed by 356
Abstract
The use of industrial solid waste to capture and fix CO2 is a promising technology for CO2 sequestration. A thermogravimetric analyzer and CO2 cement hydration mixing device were used to study the effects of mixing method, curing system, temperature, CO [...] Read more.
The use of industrial solid waste to capture and fix CO2 is a promising technology for CO2 sequestration. A thermogravimetric analyzer and CO2 cement hydration mixing device were used to study the effects of mixing method, curing system, temperature, CO2 concentration and other factors on the carbon fixation amount and performance of the circulating fluidized bed fly ash cement-based material system. The results showed that the carbon fixation and early strength of the cementitious materials could be improved by adding CO2 in the stirring process and making CO2 directly participate in the process reaction. The cementing materials samples prepared with CO2 were cured in a standard curing box for 2 days and a carbon atmosphere for 1 day, the carbon fixation amount of the cementing material was increased by 33% and the compressive strength of the cementing material was also improved. This is because under the combined action of carbon mixing and carbon curing, the prepared binding materials produced more Ca(OH)2 in the early stage, and it reacts with the introduced CO2 to form CaCO3. The strength of the calcium carbonate crystals is higher than the strength of the earlier stage of cement, and at the same time, the samples would solidify more CO2. Considering the carbon fixation amount, sample performance and solid waste utilization rate, the best conditions for the cementing materials are as follows: the content of the circulating fluidized bed fly ash (CFA) was 35%, the concentration of carbon curing was 30%, the curing temperature was 40 ℃, the water-binder ratio was 0.4, and the carbon fixation amount of the cementing material could reach about 20%. The use of CFBFA to solidify and storge CO2 is not only a new way to utilize high value-added fly ash resources, but also beneficial for reducing industrial carbon dioxide emissions. Full article
(This article belongs to the Special Issue Development and Characterization of New Construction Materials and Coatings)
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14 pages, 8454 KiB  
Article
Research on the Performance of Steel Strand-Reinforced Reactive Powder Concrete with Mixed Steel Fibers and Basalt Fibers under the Salt Dry–Wet Erosion
by Di Wang, Zhiqiang Xu, Zihao Cao, Na Xu, Chuanqi Li, Xu Tian and Hui Wang
Coatings 2024, 14(7), 833; https://doi.org/10.3390/coatings14070833 - 3 Jul 2024
Viewed by 557
Abstract
In this study, the properties of steel strand-reinforced reactive powder concrete (RPC) with mixed steel fibers and basalt fibers were investigated. The volume ratios of steel fibers and basalt fibers ranged from 0% to 2%. The reinforcement ratio of steel strands was 1%. [...] Read more.
In this study, the properties of steel strand-reinforced reactive powder concrete (RPC) with mixed steel fibers and basalt fibers were investigated. The volume ratios of steel fibers and basalt fibers ranged from 0% to 2%. The reinforcement ratio of steel strands was 1%. The flexural strength and toughness were measured. Moreover, the impact toughness was determined. The studies were carried out under an erosion environment with chlorides and sulfates. The electrical resistance and the ultrasonic velocity were obtained to assess the salt corrosion resistance performance of steel strand-reinforced RPC. The results show that the addition of basalt fibers and steel fibers can improve the mechanical strength, ultrasonic velocity, flexural toughness, and impact toughness and decrease the performance degradation of the steel strand-reinforced RPC under the conditions of dry–wet alternations of NaCl and Na2SO4 solutions. Basalt fibers and steel fibers can improve the steel strand-reinforced RPC’s flexural strength by rates of up to 13.1% and 28.7%, respectively. Moreover, the corresponding compressive strength increases by 10.3% and 18.3%. The flexural strength decreases by 11.2%~33.6% and 7.3%~22.7% after exposure to the NaCl and Na2SO4 dry–wet alternations. Meanwhile, the corresponding compressive strength decreases by 22.1%~38.9% and 14.6%~41.3%. The electrical resistance increases with the addition of basalt fibers and decreases with the increasing dosages of steel fibers. The steel strand-reinforced RPC with the assembly units of 1% steel fibers and 1% basalt fibers shows the optimal mechanical properties and salt resistance considering its wet–dry alternation performance. The properties of steel strand-reinforced RPC decrease more rapidly after undergoing NaCl erosion than Na2SO4 erosion. Full article
(This article belongs to the Special Issue Development and Characterization of New Construction Materials and Coatings)
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14 pages, 4574 KiB  
Article
Research on Fatigue Performance of Fast-Melting SBS/Epoxy Resin Composite-Modified Asphalt
by Bo Men, Xiaoyu Li, Tianyu Sha, Fei Guo, Guoqi Tang and Jinchao Yue
Coatings 2024, 14(7), 789; https://doi.org/10.3390/coatings14070789 - 25 Jun 2024
Cited by 1 | Viewed by 532
Abstract
A high-performance composite modifier ER-SBS-T was prepared through the mixing of epoxy resin with a fast-melting styrene–butadiene–styrene modifier (SBS-T) to enhance material properties. This study evaluated the fatigue characteristics of ER-SBS-T-modified asphalt using a linear amplitude sweep test, and 70# base asphalt, SBS-modified [...] Read more.
A high-performance composite modifier ER-SBS-T was prepared through the mixing of epoxy resin with a fast-melting styrene–butadiene–styrene modifier (SBS-T) to enhance material properties. This study evaluated the fatigue characteristics of ER-SBS-T-modified asphalt using a linear amplitude sweep test, and 70# base asphalt, SBS-modified asphalt, and SBS-T-modified asphalt were used as control groups. The fatigue life of ER-SBS-T-modified asphalt was determined according to viscoelastic continuous damage (VECD) theory. The findings indicated that as the ER-SBS-T modifier content increased, both the maximum value and the cumulative damage limit value increased, while the rate of change of decreased. At strain levels of 2.5% and 1%, the fatigue life of the modified asphalt improved with increasing ER-SBS-T content. However, at a strain level of 5%, the modified asphalt exhibited no significant trend in fatigue life across different ER-SBS-T contents. ER-SBS-T-modified asphalt with a modifier content of >10% demonstrated favorable fatigue performance suitable for practical engineering applications. Full article
(This article belongs to the Special Issue Development and Characterization of New Construction Materials and Coatings)
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15 pages, 6367 KiB  
Article
Study on Stable Loose Sandstone Reservoir and Corresponding Acidizing Technology
by Wei Song, Kun Zhang, Daqiang Feng, Qi Jiang, Hai Lin, Li Liao, Ruixin Kang, Baoming Ou, Jing Du, Yan Wang and Erdong Yao
Coatings 2024, 14(6), 667; https://doi.org/10.3390/coatings14060667 - 24 May 2024
Viewed by 514
Abstract
The Sebei gas field is in the Sanhu depression area of the Qaidam Basin, which is the main gas-producing area and a key profit pillar for the Qinghai oilfield. The Sebei gas field within the Qinghai oilfield is characterized by high mud content, [...] Read more.
The Sebei gas field is in the Sanhu depression area of the Qaidam Basin, which is the main gas-producing area and a key profit pillar for the Qinghai oilfield. The Sebei gas field within the Qinghai oilfield is characterized by high mud content, poor lithology, interflow between gas and water layers, and a propensity for sand production. The reservoir rocks are predominantly argillaceous siltstone with primarily argillaceous cement. These rocks are loose and tend to produce sand, which can lead to blockage. During its development, the Sebei gas field exhibited significant issues with scale formation and sand production in gas wells. Conventional acidization technologies have proven to be slow acting and may even result in adverse effects. These methods can cause loose sandstone to disperse, exacerbating sand production. Therefore, it is necessary to elucidate the mechanisms of wellbore plugging and to develop an acidizing system for plug removal that is tailored to unconsolidated sandstone reservoirs. Such a system should not only alleviate gas well plugging damage but also maintain reservoir stability and ensure efficient and sustained stimulation from acidization treatments. In this paper, the stability of unconsolidated sandstone reservoirs and the acid dissolution plugging system, along with the technological methods for stabilizing sand bodies, are studied through mineral component analysis, acid dissolution experiments, core immersion experiments, and other laboratory tests. The principle of synergistic effects between different acids is applied to achieve “high-efficiency scale dissolution and low sandstone dissolution”. Three key indicators of dispersion, sand dissolution rate, and scale dissolution rate were created. The acid plugging solution formula of “controlled dispersion and differentiated dissolution” was developed to address these indicators. Laboratory tests have shown that the sandstone is predominantly composed of quartz and clay minerals, with the latter mainly being illite. The primary constituent of the wellbore blockage scale sample is magnesium carbonate, which exhibits nearly 100% solubility in acid. By adding a stabilizer prior to acid corrosion, the core’s corrosion can be effectively mitigated, particle dispersion and migration can be controlled, and the rock structure’s stability can be maintained. Laboratory evaluations indicate that the scale dissolution rate is greater than or equal to 95%, the sand dissolution rate is below 25%, and the system achieves a differentiated corrosion effect without dispersion for 24 h. Field tests demonstrate that the new acid solution plugging removal system enhances average well production and reduces operational costs. The system effectively mitigates the challenges of substantial sand production and reservoir dispersion, thereby furnishing a theoretical foundation and practical direction for acid plugging treatments in unconsolidated sandstone gas fields. Full article
(This article belongs to the Special Issue Development and Characterization of New Construction Materials and Coatings)
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17 pages, 30170 KiB  
Article
Study on the Characteristics and Mechanism of Shield Tunnel Mud Cake Disintegration in Complex Red-Bed Geology
by Jinshuo Yan, Xingwei Xue, Chaofan Gong and Kexin Zhang
Coatings 2024, 14(5), 567; https://doi.org/10.3390/coatings14050567 - 2 May 2024
Viewed by 770
Abstract
The complex red-bed geology is primarily composed of iron-rich sedimentary rock layers with clay minerals as a major component. The soil water content exceeds 30%, and its high viscosity and water content lead to the easy formation of mud cake on the cutterhead, [...] Read more.
The complex red-bed geology is primarily composed of iron-rich sedimentary rock layers with clay minerals as a major component. The soil water content exceeds 30%, and its high viscosity and water content lead to the easy formation of mud cake on the cutterhead, endangering the safety and progress of construction, which poses a significant challenge for tunnel boring machines (TBMs). The use of dispersants to eliminate mud cake is a common method in engineering projects. This paper presents an improved disintegration experiment instrument to study the disintegration characteristics of mud cake from the red-bed geology under different dispersant solutions, proposing a dispersant formulation suitable for the red-bed geology of the Haizhu Bay Tunnel project. The results indicate that mud cake samples exhibit a moderate disintegration effect in pure water. Furthermore, it has been observed that the disintegration effect decreases as the thickness of mud cake increases. Sodium silicate solution was not suitable for treating the red-bed geological mud cake, while sodium hexametaphosphate and oxalic acid solutions had a good promoting effect on the disintegration of red-bed geological mud cake. However, there was a threshold for the dispersant concentration; exceeding this threshold actually worsened the disintegration effect. Ultimately, the engineering application of a 10% oxalic acid solution, which proved effective in disintegrating the mud cake, significantly enhanced the excavation efficiency in the Haizhu Bay Tunnel project. Full article
(This article belongs to the Special Issue Development and Characterization of New Construction Materials and Coatings)
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19 pages, 6293 KiB  
Article
The Corrosion Resistance of Concrete-Filled Steel Tubes with the Assembly Unit of Na2MoO4 and Benzotriazole
by Di Wang, Zhiqiang Xu, Na Xu, Zengliang Hu, Hui Wang and Feiting Shi
Coatings 2024, 14(3), 349; https://doi.org/10.3390/coatings14030349 - 14 Mar 2024
Cited by 1 | Viewed by 1029
Abstract
Steel pipes are commonly used to strengthen the concrete’s load-bearing capacity. However, they are prone to corrosion in salt erosion environments. In this study, the influence of Na2MoO4 and benzotriazole on concrete-filled steel tubes’ corrosion performance is investigated. The steel [...] Read more.
Steel pipes are commonly used to strengthen the concrete’s load-bearing capacity. However, they are prone to corrosion in salt erosion environments. In this study, the influence of Na2MoO4 and benzotriazole on concrete-filled steel tubes’ corrosion performance is investigated. The steel pipes’ mass loss rates (MRs), ultrasonic velocity, electrical resistance, and the AC impedance spectrum and Tafel curves of concrete-filled steel tubes were used to characterize the degree of corrosion in the steel pipes. Scanning electron microscopy–energy-dispersive spectrometry and X-ray diffraction were used for studying the composition of steel pipe rust. The research results revealed that the NaCl freeze–thaw cycles (F-C) and NaCl dry–wet alternation (D-A) actions had a reducing effect on the mass and ultrasonic velocity of the concrete-filled steel tubes. After 300 NaCl F-C and 30 NaCl D-A, the MRs were 0%~0.00470% and 0%~0.00666%. The corresponding ultrasonic velocities were 0%~21.1% and 0%~23.6%. When a rust inhibitor was added, the results were the opposite. The MRs decreased by 0%~80.3% and 0%~81.6% with the added Na2MoO4 and benzotriazole. Meanwhile, the corresponding ultrasonic velocities were 0%~8.1% and 0%~8.3%. The steel tubes were corroded after 300 NaCl F-C and 30 NaCl D-A. The addition of rust inhibitors improved the corrosion resistance of the concrete-filled steel tubes by increasing the electrical resistance before NaCl erosion. The corrosion area rate decreased by using the rust inhibitors. The corrosion resistance effect of benzotriazole was higher than that of Na2MoO4. The concrete-filled steel tube with an assembly unit comprising 5 kg/m3 of Na2MoO4 and 15 kg/m3 of benzotriazole had the best corrosion resistance under the erosion induced by NaCl F-C and D-A. Rust inhibitors reduced the content of iron-containing crystals and iron elements. The specimens with 5 kg/m3 Na2MoO4 and 15 kg/m3 benzotriazole had the lowest concentration of iron-containing crystals and iron elements. Full article
(This article belongs to the Special Issue Development and Characterization of New Construction Materials and Coatings)
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19 pages, 10815 KiB  
Article
The Influence of TiO2 Nanoparticles on the Physico–Mechanical and Structural Characteristics of Cementitious Materials
by Carmen T. Florean, Horatiu Vermesan, Gyorgy Thalmaier, Bogdan V. Neamtu, Timea Gabor, Cristina Campian, Andreea Hegyi and Alexandra Csapai
Coatings 2024, 14(2), 218; https://doi.org/10.3390/coatings14020218 - 9 Feb 2024
Cited by 3 | Viewed by 1185
Abstract
The urgent need for sustainable construction that corresponds to the three pillars of sustainable development is obvious and continuously requires innovative solutions. Cementitious composites with TiO2 nanoparticles (NT) addition show potential due to their improved durability, physico–mechanical characteristics, and self-cleaning capacity. This [...] Read more.
The urgent need for sustainable construction that corresponds to the three pillars of sustainable development is obvious and continuously requires innovative solutions. Cementitious composites with TiO2 nanoparticles (NT) addition show potential due to their improved durability, physico–mechanical characteristics, and self-cleaning capacity. This study aimed to evaluate the influence of NT on cementitious composites by comparing those with 2%–5% nanoparticles with a similar control sample without nanoparticles, as well as an analysis of cost growth. The experimental results showed an increase in bulk density of the material (4.7%–7.4%), reduction in large pore sizes by min. 12.5%, together with an increase in cumulative volume and cumulative specific surface area of small pore sizes, indicating densification of the material, also supported by SEM, EDS, and XRD analyses indicating acceleration of cement hydration processes with formation of specific products. The changes at microstructural level support the experimental results obtained at macrostructural level, i.e., modest but existent increases in flexural strength (0.6%–7.9%) and compressive strength (0.2%–2.6%) or more significant improvements in abrasion resistance (8.2%–58%) and reduction in water absorption coefficient (37.5%–81.3%). Following the cost–benefit analysis, it was concluded that, for the example case considered of a pedestrian pavement with a surface area of 100 m2, using 100 mm thick slabs, if these slabs were to be made with two layers, the lower layer made of cementitious composite as a reference and the upper layer with a thickness of 10 mm made of cementitious composite with 3% NT or 4% NT, the increase in cost would be acceptable, representing less than 15% compared to the cost for the exclusive use of cementitious composite without NT. Full article
(This article belongs to the Special Issue Development and Characterization of New Construction Materials and Coatings)
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17 pages, 4839 KiB  
Article
The Influence of Salt Erosion on the Mechanical Performances of Ultra-High-Performance Concrete with Secondary Aluminum Dross
by Houchao Sun, Weixiang Sun, Feiting Shi, Lu Miao and Hui Wang
Coatings 2024, 14(2), 189; https://doi.org/10.3390/coatings14020189 - 1 Feb 2024
Viewed by 916
Abstract
Secondary aluminum dross containing a large amount of active substance can be used to prepare concrete. The mechanical strengths, the mass loss rate (MR) and the relative dynamic modulus of elasticity (RME) of ultra-high-performance concrete with secondary aluminum dross are researched. The NaCl [...] Read more.
Secondary aluminum dross containing a large amount of active substance can be used to prepare concrete. The mechanical strengths, the mass loss rate (MR) and the relative dynamic modulus of elasticity (RME) of ultra-high-performance concrete with secondary aluminum dross are researched. The NaCl freeze–thaw cycles (F-Cs) and dry–wet alternation (D-A) effects with NaCl and Na2SO4 are considered. The corresponding permeability of chloride ions and the carbonation depth (Dc) are obtained. The scanning electron microscope (SEM) photos are researched to reveal the variation of the mechanical mechanism. Results show that after specimens’ suffering from the action of 20 NaCl D-As, the MR of ultra-high-performance concrete is the highest. Specimens exposed to 200 NaCl F-Cs show the lowest MR and CMC. The RME of UHPC under salt actions increase in the order of 20 NaCl D-As < 20 Na2SO4 D-As < 200 NaCl F-Cs. After suffering 200 NaCl F-Cs, 20 Na2SO4 D-As and 20 NaCl D-As, the corresponding Dc values are 1.86 mm to 2.31 mm, 1.79 mm to 2.23 mm and 2.11 mm to 2.76 mm. The flexural strength decreases at the rates of 0.99%–25%, 3.92%–27.84% and 1.47%–21.59% respectively. The MR increases and the RME decreases as the cubic function changes with the amount of salt erosion. After the secondary aluminum dross is added, the CMC decreases at the rates of 0% to 11.53%, 0% to 33.17% and 0% to 8.41% during the process of the salt action. The SAD can reduce the Dc with the decreasing rates of 19.48%, 23.55% and 19.73%. The SAD can increase the compactness of ultra-high-performance concrete. Ultra-high-performance concrete suffering from 20 NaCl D-As shows the largest number and the highest width of cracks. However, when the specimens are exposed to 20 Na2SO4 D-As, the number of cracks is the lowest and the width is the narrowest. Full article
(This article belongs to the Special Issue Development and Characterization of New Construction Materials and Coatings)
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Review

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20 pages, 1617 KiB  
Review
A Review of Concrete Carbonation Depth Evaluation Models
by Xinhao Wang, Qiuwei Yang, Xi Peng and Fengjiang Qin
Coatings 2024, 14(4), 386; https://doi.org/10.3390/coatings14040386 - 26 Mar 2024
Cited by 1 | Viewed by 1676
Abstract
Carbonation is one of the critical issues affecting the durability of reinforced concrete. Evaluating the depth of concrete carbonation is of great significance for ensuring the quality and safety of construction projects. In recent years, various prediction algorithms have been developed for evaluating [...] Read more.
Carbonation is one of the critical issues affecting the durability of reinforced concrete. Evaluating the depth of concrete carbonation is of great significance for ensuring the quality and safety of construction projects. In recent years, various prediction algorithms have been developed for evaluating concrete carbonation depth. This article provides a detailed overview of the existing prediction models for concrete carbonation depth. According to the data processing methods used in the model, the existing prediction models can be divided into mathematical curve models and machine learning models. The machine learning models can be further divided into the following categories: artificial neural network model, decision tree model, support vector machine model, and combined models. The basic idea of the mathematical curve model is to directly establish the relationship between the carbonation depth and age of concrete by using certain function curves. The advantage of the mathematical curve model is that only a small amount of experimental data is needed for curve fitting, which is very convenient for engineering applications. The limitation of the curve model is that it can only consider the influence of some factors on the carbonation depth of concrete, and the prediction accuracy cannot be guaranteed. The advantage of using the machine learning model to predict the carbonation depth of concrete is that many factors can be considered at the same time. When there are sufficient experimental data, the trained machine learning model can give more accurate prediction results than the mathematical curve model. The main defect of the machine learning model is that it needs a lot of experimental data as training samples, so it is not as convenient as the mathematical curve model in engineering applications. A future research direction may be to combine a machine learning model with a mathematical curve model to evaluate the carbonation depth of concrete more accurately. Full article
(This article belongs to the Special Issue Development and Characterization of New Construction Materials and Coatings)
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25 pages, 3792 KiB  
Review
Structural Damage Detection Based on Static and Dynamic Flexibility: A Review and Comparative Study
by Xi Peng, Qiuwei Yang, Fengjiang Qin and Binxiang Sun
Coatings 2024, 14(1), 31; https://doi.org/10.3390/coatings14010031 - 26 Dec 2023
Viewed by 1085
Abstract
Material damage in structures must be detected in a timely manner to prevent engineering accidents. Damage detection based on structural flexibility has attracted widespread attention in recent years due to its simplicity and practicality. This article provides a detailed overview of damage detection [...] Read more.
Material damage in structures must be detected in a timely manner to prevent engineering accidents. Damage detection based on structural flexibility has attracted widespread attention in recent years due to its simplicity and practicality. This article provides a detailed overview of damage detection methods based on structural flexibility. Depending on the calculation method and data used, flexibility-based methods can be divided into the following categories: flexibility difference, flexibility derivative index, flexibility sensitivity, flexibility decomposition, static flexibility, and combinations of flexibility with other methods. The basic principles and main calculation formulas of various flexibility methods are explained, and their advantages and disadvantages are analyzed. For the method using flexibility difference, the advantage is that the calculation is very simple and does not require the construction of a finite element model of the structure. The disadvantage is that it requires the measurement of modal data of the intact structure, and this method cannot quantitatively assess the degree of damage. For the method using the flexibility derivative index, the advantage is that it only requires the modal data of the damaged structure to locate the damage, but this method is particularly sensitive to noise in the data and is prone to misjudgment. For methods based on flexibility sensitivity and flexibility decomposition, the advantage is that they can simultaneously obtain the location and degree of damage in the structure, but the disadvantage is that they require the establishment of accurate finite element models in advance. Static flexibility methods can compensate for the shortcomings of dynamic flexibility methods, but they usually affect the normal use of the structure during static testing. Combining flexibility-based methods with advanced intelligent algorithms and other methods can further improve their accuracy and efficiency in identifying structural damage. Finally, this article discusses the challenges that have not yet been solved among damage detection methods based on structural flexibility. Full article
(This article belongs to the Special Issue Development and Characterization of New Construction Materials and Coatings)
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