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Interface and Surface Modification for Durable Concretes
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Interface and Surface Modification for Durable Concretes

A special issue of Coatings (ISSN 2079-6412). This special issue belongs to the section "Surface Characterization, Deposition and Modification".

Deadline for manuscript submissions: closed (30 December 2021) | Viewed by 45797

Special Issue Editor

Prof. Dr. Xiaojian Gao

E-Mail Website
Guest Editor
School of Civil Engineering, Harbin Institute of Technology, Harbin 150001, China
Interests: concrete rheology; UHPC; concrete durability; CO2 capture
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Concrete is the most frequently used construction material in the world due to its low production cost and ease of use. The durability of concrete is very important to ensure its performance over the service life and reduce the consumption of concrete. This is attributed to the fact that durable concrete can meet the requirement for functionality, strength, stability, and safety of structures through the lifetime. The interface between the matrix and the aggregate of concrete, or the interface between the matrix and the fiber of fiber-reinforced concrete are usually known as weakness zones in concrete. The increase of porosity and possibility of cracking can increase permeability in these zones, leading to the reduction in durability. The use of coatings on the surface of aggregates or fibers can refine the microstructure of interface, hence improving the durability of concrete. It was reported that recycled coating aggregates with pozzolanic materials, such as silica fume and fly ash, can result in a stronger interface between the matrix and the aggregate, decreasing the chloride ion penetration and enhancing durability. The coating steel bars with the zinc silicate–potassium silicate can form a dense and stable film on the surfaces of steel bars. This can reduce the penetration rate of water and other ions, improving the corrosion resistance of steel bars in concrete.

Concrete surface generally contains micropores and microcracks that can provide paths for the ingress of harmful substances into the concrete, resulting in a reduction in durability. Surface treatment on concrete can increase the water-repellent and anti-icing ability of the concrete, hence improving the durability of concrete, such as freeze–thaw resistance, permeability, and sulfate resistance. Such surface treatment involves the use of hydrophobic and film-forming coating materials that can act as a barrier to isolate the concrete from its surrounding environment. It is well-known that hydrophobic surface treatment with silanes can eliminate surface scaling significantly, resulting in the increase in freeze–thaw resistance. The use of a silica-based hybrid nanocomposite (SiO2/polymethylhydrosiloxane) that has pozzolanic reactivity and hydrophobicity can refine the surface structure and reduce the water absorption of concrete, leading to improvement in permeability. Epoxy- and silane-based surface treatment materials can also act as protective film and water repellents. This can reduce the penetration of sulfates into concrete and enhance concrete’s ability to resist sulfate attacks.

This Special Issue will serve as a forum for papers on the following concepts:

  • Durable concrete;
  • Functional concrete;
  • Impair concrete;
  • Innovative concrete technology;
  • Other aspects of cement-based materials.

Dr. Xiaojian Gao
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

  • Concrete durability
  • Interface modification
  • Water repellent
  • Anti-icing
  • Surface renovation

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Published Papers (19 papers)

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Research

17 pages, 4200 KiB  
Article
Influence of Rust Inhibitors on the Microstructure of a Steel Passive Film in Chloride Concrete
by Qun Guo, Xiaozhen Li, Nan Lin and Junzhe Liu
Coatings 2022, 12(5), 692; https://doi.org/10.3390/coatings12050692 - 18 May 2022
Cited by 7 | Viewed by 1772
Abstract
To compare the corrosion inhibition behaviors of rust inhibitors with different mechanisms on steel bars, the rust resistance effect of sodium molybdate (Na2MoO4), sodium chromate (Na2CrO4), benzotriazole (BTA), N-N dimethyl ethanolamine, sodium molybdate (Na2 [...] Read more.
To compare the corrosion inhibition behaviors of rust inhibitors with different mechanisms on steel bars, the rust resistance effect of sodium molybdate (Na2MoO4), sodium chromate (Na2CrO4), benzotriazole (BTA), N-N dimethyl ethanolamine, sodium molybdate (Na2MoO4) + benzotriazole (BTA), and sodium chromate (Na2CrO4) + benzotriazole (BTA) on steel bars in a simulated chloride concrete pore solution was studied. The rust resistance effects of different types of rust inhibitors were assessed by electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The effects of different types of rust inhibitors on the film formation characteristics of a passive film on a steel bar surface were expounded. The results show that: When sodium molybdate (Na2MoO4) and benzotriazole (BTA) acted together, the impedance value and the capacitive reactance arc radius were the largest, and the density of the passive film and the inhibition efficiency were the highest. The composition of the passive film was primarily composed of iron compounds, and it also contained oxide and adsorption films that were formed on the steel bar surface by the rust inhibitors. The rust resistance effect was proportional to the compactness of the passive film. Full article
(This article belongs to the Special Issue Interface and Surface Modification for Durable Concretes)
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14 pages, 5138 KiB  
Article
The Effect of Magnesium Chloride on the Macroscopic and MI-Croscopic Properties of Phosphate Cement-Based Materials
by Yubing Du, Zhaoyu Wang, Peiwei Gao, Jianming Yang, Shucong Zhen, Hui Wang and Tao Du
Coatings 2022, 12(3), 370; https://doi.org/10.3390/coatings12030370 - 10 Mar 2022
Cited by 3 | Viewed by 2143
Abstract
Phosphate cement-based materials are fast-hardening cement materials, which have been applied to the rapid repair of concrete structures. However, the excessive setting rate could lead to initial cracks in the cement-based matrix. Therefore, a proper retarder is required to reduce the setting rate, [...] Read more.
Phosphate cement-based materials are fast-hardening cement materials, which have been applied to the rapid repair of concrete structures. However, the excessive setting rate could lead to initial cracks in the cement-based matrix. Therefore, a proper retarder is required to reduce the setting rate, thus improving the strength of structures. In this study, a magnesium chloride retarder was selected, and its influence on the setting time, slump flow, and the mechanical strengths (flexural strength, compressive strength, and bond strength) of phosphate cement paste curing for 3 h~28 d was investigated. Scanning electron microscopy, X-ray diffraction, and thermal analysis were used to analyze the mechanism of the properties of phosphate cement paste. Results showed that the setting time increased exponentially with the mass ratio of magnesium chloride by the total mass of magnesium oxide. Meanwhile, the slump flow increased linearly with the increasing dosage of magnesium chloride, and the drying shrinkage rate exhibited a quadratic function with the curing age. The addition of magnesium chloride decreased the mechanical strengths of phosphate cement paste at earlier curing age (lower than 3 d) and effectively improved the mechanical strengths at a later curing age (equal to or higher than 3 d). Moreover, magnesium chloride could also decrease the drying shrinkage rate. It can be obtained from the microcosmic researching results that magnesium chloride can inhibit the hydration of phosphate cement and reduce cracks induced by drying shrinkage at later curing age (higher than 3 d). Full article
(This article belongs to the Special Issue Interface and Surface Modification for Durable Concretes)
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21 pages, 37075 KiB  
Article
A Study on Impact of Different Surface Treatment Agents on the Durability of Airport Pavement Concrete
by Tianlun Li, Yonggen Wu and Haoxiang Wu
Coatings 2022, 12(2), 162; https://doi.org/10.3390/coatings12020162 - 27 Jan 2022
Cited by 7 | Viewed by 2437
Abstract
Concrete surface treatment is one of effective methods to increase the durability of concrete. This study chose tetraethyl orthosilicate (TEOS), lithium silicate (Li2SiO3), SiO2 nanoparticles (nano-SiO2) as surface treatment agents, tested their resistance to water penetration, [...] Read more.
Concrete surface treatment is one of effective methods to increase the durability of concrete. This study chose tetraethyl orthosilicate (TEOS), lithium silicate (Li2SiO3), SiO2 nanoparticles (nano-SiO2) as surface treatment agents, tested their resistance to water penetration, chloride ion penetration, frost, sulfate erosion and abrasion of concrete specimens with different strengths, compared and evaluated the impacts to the durability of concrete by using three surface treatment agents, researched the impact of concrete strength on the surface treatment effects, and analyzed the mechanism of these surface treatment agents in connection with microscopic tests. It was found that all three agents can improve the durability of concrete, of which, the treatment effect from using tetraethyl orthosilicate (TEOS) was the best; however, along with the improvement of concrete strength, its other effects were gradually reinforced except for some small improvement effect in resistance to frost, which means it is an ideal concrete surface treatment agent; for lithium silicate (Li2SiO3), the improvement effect of resistance to frost was the best with little impact on the strength of the concrete, however, the other performance improvement effects were a little bit worse than that of tetraethyl orthosilicate (TEOS), which means it is more suitable for airport pavement with a higher concrete resistance to frost; For SiO2 nanoparticles (Nano-SiO2), the surface treatment effect was extreme limited, not recommended to be solely used for airport pavement with its requirement of high resistance to frost. Upon scanning electron microscope (SEM), X-ray diffraction (XRD), fourier transform infrared radiation (FTIR) and thermo gravimetric analyzer (TGA) tests, the surfaced concrete specimens did not produce any new substances, and the effect of the surface treatment agents was mainly to improve the concrete performance by physical filling, or by filling the cavities with the hydrated calcium silicate gel produced in the chemical reaction. These results may direct the selection of surface treatment agents in airport engineering. Full article
(This article belongs to the Special Issue Interface and Surface Modification for Durable Concretes)
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14 pages, 7196 KiB  
Article
Influence of Dolomite Rock Powder and Iron Tailings Powder on the Electrical Resistivity, Strength and Microstructure of Cement Pastes and Concrete
by Yang Liu, Wenru Hao, Wei He, Xia Meng, Yinlan Shen, Tao Du and Hui Wang
Coatings 2022, 12(1), 95; https://doi.org/10.3390/coatings12010095 - 14 Jan 2022
Cited by 13 | Viewed by 2521
Abstract
Dolomite rock powder (the waste stone residue in the production of machine-made sand and stone processing) and iron tailings powder formed by mineral processing industry are solid wastes, which occupy land resources, pollute the environment and release toxic substances without reasonable processing. The [...] Read more.
Dolomite rock powder (the waste stone residue in the production of machine-made sand and stone processing) and iron tailings powder formed by mineral processing industry are solid wastes, which occupy land resources, pollute the environment and release toxic substances without reasonable processing. The dolomite rock powder and iron tailings powder composing a large number of active substances could be advantageous to the cement-based materials. In this study, the electrical resistivity of cement paste and concrete was measured. Meanwhile, the influence of dolomite rock powder and iron tailings powder on the compressive strength of concrete was investigated. The electric flux of concrete was determined to estimate the chloride ion permeability. The scanning electron microscope (SEM) and X-ray diffraction were obtained to investigate the hydration of cement paste. Results showed the electrical resistivity of all specimens presented in this order: specimens with iron tailings < specimens with dolomite rock powder < blank specimens < specimens with ground granulated blast-furnace slag (GGBS) < specimens with fly ash. The correlation between electrical resistivity and curing age of cement paste or concrete has been deduced as a quadratic function. The addition of GGBS could improve the compressive strength of concrete. Meanwhile, when the other three types of mineral admixtures were added, 5% by mass ratio of the total binder materials was the optimum for the compressive strength. The curing ages, the fly ash, the GGBS and 5% dolomite rock powder or 5% iron tailings powder demonstrated a positive effect on the chloride ion impermeability. However, when higher dosages of dolomite rock powder or iron tailings powder were added, the effect was the opposite. Finally, the compactness of the microstructure and the Ca(OH)2 of cement paste could be improved by a small dosage of dolomites or iron tailings (less than 5%). Full article
(This article belongs to the Special Issue Interface and Surface Modification for Durable Concretes)
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12 pages, 4939 KiB  
Article
Influence of Recycled Concrete Powder (RCP) and Recycled Brick Powder (RBP) on the Physical/Mechanical Properties and Durability of Raw Soil
by Li’an Zhou, Yang Liu, Jiacheng Lu, Wenjuan Zhou and Hui Wang
Coatings 2021, 11(12), 1475; https://doi.org/10.3390/coatings11121475 - 30 Nov 2021
Cited by 9 | Viewed by 2255
Abstract
The influence of recycled concrete powder (RCP) and recycled brick powder (RBP) on the dry density, optimal water content, and compressive strength of raw soil materials was investigated in this study. Moreover, the following resistance of freeze–thaw cycles was also considered. Additionally, X-ray [...] Read more.
The influence of recycled concrete powder (RCP) and recycled brick powder (RBP) on the dry density, optimal water content, and compressive strength of raw soil materials was investigated in this study. Moreover, the following resistance of freeze–thaw cycles was also considered. Additionally, X-ray diffraction (XRD) and scanning electron microscope (SEM) were selected to detect its mineral composition and observe the microstructure, further revealing the mechanism of performance change. The mass ratios of recycled concrete powder and recycled brick powder were 2~14%. Results showed that the dry density decreased and the optimal water content increased with the increasing dosage of recycled concrete powder and recycled brick powder. When the dosage of RCP or RBP was lower than 14%, raw soil with RCP showed higher optimal water content and lower dry density. However, when the dosage was higher than 14%, the result was the opposite. The addition of recycled concrete powder and recycled brick powder was able to decrease the compressive strength of raw soil, except for 10% of recycled brick powder. Raw soil with recycled brick powder presented higher compressive strength than that of raw soil with recycled concrete powder. RBP could improve the freeze–thaw cycles’ resistance of specimens; however, RCP led to decreasing the resistance of freeze–thaw cycles. These research findings can provide reference to the recycling of construction waste. Full article
(This article belongs to the Special Issue Interface and Surface Modification for Durable Concretes)
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18 pages, 3640 KiB  
Article
Experimental Study on Axial Compressive Behavior of Gangue Aggregate Concrete Filled FRP and Thin-Walled Steel Double Tubular Columns
by Jian Wang, Junwu Xia, Hongfei Chang, Youmin Han, Linli Yu and Li Jiang
Coatings 2021, 11(11), 1404; https://doi.org/10.3390/coatings11111404 - 18 Nov 2021
Cited by 5 | Viewed by 1832
Abstract
In the present paper, the monotonic axial compression test of gangue aggregate concrete filled Fiber reinforced polymer (FRP) and thin-walled steel double tubular columns (DTCC) was carried out, and the gangue aggregate concrete filled FRP tubular columns (CFFT) were designed as a comparison. [...] Read more.
In the present paper, the monotonic axial compression test of gangue aggregate concrete filled Fiber reinforced polymer (FRP) and thin-walled steel double tubular columns (DTCC) was carried out, and the gangue aggregate concrete filled FRP tubular columns (CFFT) were designed as a comparison. The main experimental factors were the confinement level of the FRP jacket, the relative diameter ratio (the ratio of the outer diameter of the steel tube to the inner diameter of the FRP jacket), and the different strengths of gangue aggregate concrete. The test results show that the bearing capacity and ductility of gangue aggregate concrete in CFFT were significantly improved. As the local buckling of thin-walled steel tube was effectively inhibited, the load bearing capacity of DTCC was further improved compared with CFFT, but the change of dilation behavior and ductility was insignificant. By analyzing the bi-directional stress state of the steel tube, the confinement level of the external FRP jacket was the most sensitive factor affecting the hoop stress of the steel tube, and the axial stress was obviously weakened under the bi-directional stress state. In addition, with the increase of steel tube diameter, the confinement effect of steel tube in DTCC became more obvious. Full article
(This article belongs to the Special Issue Interface and Surface Modification for Durable Concretes)
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14 pages, 3616 KiB  
Article
Influence of NaCl Freeze–Thaw Cycles on the Mechanical Strength of Reactive Powder Concrete with the Assembly Unit of Sulphoaluminate Cement and Ordinary Portland Cement
by Zhangjie Cai and Hui Wang
Coatings 2021, 11(10), 1238; https://doi.org/10.3390/coatings11101238 - 12 Oct 2021
Cited by 11 | Viewed by 2029
Abstract
The influence of sulphoaluminate cement and the dosage of polypropylene fibers on the basic mechanical strengths (compressive and flexural strengths) of reactive powder concrete (RPC) cured for 1 d, 3 d, 7 d, 14 d and 28 d is studied in this research. [...] Read more.
The influence of sulphoaluminate cement and the dosage of polypropylene fibers on the basic mechanical strengths (compressive and flexural strengths) of reactive powder concrete (RPC) cured for 1 d, 3 d, 7 d, 14 d and 28 d is studied in this research. The content of sulphoaluminate cement ranges from 0% to 100% and the dosages of polypropylene fibers are 0%~3.5%, respectively. Moreover, the mechanical properties (compressive and flexural strengths), the relative dynamic elastic modulus (RDEM) and the chloride permeability of specimens with 50% sulphoaluminate cement and different dosages of polypropylene fibers are determined after the specimens are exposed to different NaCl freeze–thaw cycles. The water–binder ratio in this study is 0.25, and the sand-to-binder ratio is 1.25. Results show that the relationship between the mechanical strengths of RPC at early curing ages (lower than 7 d) and the sulphoaluminate cement content is a linear function with a positive correlation. However, when the curing age reaches 14 d, the compressive and flexural strengths decrease in the form of a linear function with the addition of sulphoaluminate cement. The correlation between the mechanical strengths and polypropylene fiber volume is a positive quadratic function. However, the mass loss rate and flexural strength loss rate increased in the form of a quadratic function, and RDEM shows a negative quadratic function with the freeze–thaw cycles. Moreover, the compressive strength loss rate increases linearly with the freeze–thaw cycle. The addition of polypropylene fibers can effectively improve the freeze–thaw resistance of cement mortar with an assembly unit of ordinary cement and sulphoaluminate cement. Full article
(This article belongs to the Special Issue Interface and Surface Modification for Durable Concretes)
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23 pages, 78317 KiB  
Article
Analysis of Additives in Gypsum Coatings Based on Melamine, Polycarbonate Salts, Polycarboxylate, and Polycarboxylic Acids
by José Antonio Flores Yepes, Luis Miguel Serna Jara, Antonio Martínez Gabarrón, Ana María Codes Alcaraz and Joaquín Julián Pastor Pérez
Coatings 2021, 11(10), 1204; https://doi.org/10.3390/coatings11101204 - 30 Sep 2021
Cited by 2 | Viewed by 2968
Abstract
In this paper, we evaluate different gypsum coating additives that are available on the market, which are categorized by their chemical bases. The results will serve as a reference for future investigations of new additive bases in order to improve the properties of [...] Read more.
In this paper, we evaluate different gypsum coating additives that are available on the market, which are categorized by their chemical bases. The results will serve as a reference for future investigations of new additive bases in order to improve the properties of gypsum. As such, the objective of the this study is to assess the workability, mechanical behavior, and crystalline structure of calcium sulfate combined with different retarding and fluidifying bases, including melamine bases, which have a compressive strength of 19.32 N/mm2 and handling times with polycarbonate salts of up to 117.58 min. The following study presents the results of standard mechanical tests, analyzing semi-hydrated calcium sulfate (without additives) as a reference, along with the addition of melamines, synthetic melanin polymers, polycarbonate salts, polycarboxylates, and a polycarboxylic acid (citric acid). We already know that the addition of these additives will modify the mechanical properties of calcium sulfate, such as the Shore C surface hardness, flexural strength, modulus of elasticity, and compression resistance, which is the object of this study. Full article
(This article belongs to the Special Issue Interface and Surface Modification for Durable Concretes)
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14 pages, 2316 KiB  
Article
Coupling Effect of Salt Freeze-Thaw Cycles and Carbonation on the Mechanical Performance of Quick Hardening Sulphoaluminate Cement-Based Reactive Powder Concrete with Basalt Fibers
by Guoping Huang, Hui Wang and Feiting Shi
Coatings 2021, 11(9), 1142; https://doi.org/10.3390/coatings11091142 - 20 Sep 2021
Cited by 20 | Viewed by 2692
Abstract
The effect of salt freeze-thaw cycles coupled with carbonation on the mechanical performance of quick hardening sulphoaluminate cement-based reactive powder concrete combined with basalt fibers was investigated. The ratios of basalt fibers in sulphoaluminate cement-based reactive powder concrete (SAC-RPC) were 1%, 2%, 3% [...] Read more.
The effect of salt freeze-thaw cycles coupled with carbonation on the mechanical performance of quick hardening sulphoaluminate cement-based reactive powder concrete combined with basalt fibers was investigated. The ratios of basalt fibers in sulphoaluminate cement-based reactive powder concrete (SAC-RPC) were 1%, 2%, 3% and 4% by the volume of concrete. The mechanical strengths (compressive strength, flexural strength and bonding strength) of SAC-RPC were investigated after curing for 5 h, 1 d, 14 d and 28 d, respectively. Meanwhile, the mechanical strengths of resultant concrete were detected, when different NaCl freeze-thaw cycles and carbonation were adopted. Results showed that the addition of basalt fibers could effectively improve the mechanical strengths, especially the flexural strength of SAC-RPC. The dosage of 3.0% was the threshold value affected mechanical strengths. The flexural, compressive and bonding strengths of SAC-RPC were higher than 8.53 MPa, 34 MPa and 3.21 MPa, respectively. The mass loss and mechanical strengths loss of SAC-RPC increased in the form of quadratic function with the increasing number of NaCl freeze-thaw cycles and varied in the form of quadratic decreasing function. Meanwhile, the effect of carbonation on the mechanical strengths of SAC-RPC can be ignored. Additionally, the coupling effect of salt freeze-thaw cycles and carbonation could accelerate the attenuation of concrete strength. The mechanical strengths loss demonstrated a decreased quadratic function with the increasing volume of basalt fibers. Full article
(This article belongs to the Special Issue Interface and Surface Modification for Durable Concretes)
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12 pages, 2307 KiB  
Article
Influence of Coarse Aggregate Type on the Mechanical Strengths and Durability of Cement Concrete
by Lin Wang, Han Yong, Jinyu Lu, Chunxue Shu and Hui Wang
Coatings 2021, 11(9), 1036; https://doi.org/10.3390/coatings11091036 - 28 Aug 2021
Cited by 5 | Viewed by 2139
Abstract
In this paper, the influence of coarse aggregate on the slump flow and the following mechanical strengths (flexural and compressive strengths), the shrinkage rate, the chloride penetration resistance, and the freeze–thaw resistance were investigated. Water–binder ratios in this study were 0.22, 0.30, 0.34, [...] Read more.
In this paper, the influence of coarse aggregate on the slump flow and the following mechanical strengths (flexural and compressive strengths), the shrinkage rate, the chloride penetration resistance, and the freeze–thaw resistance were investigated. Water–binder ratios in this study were 0.22, 0.30, 0.34, and 0.45. Sand ratio in this study was 0.45. All samples were cured for 7 d, 14 d, 28 d, and 56 d, respectively. Results indicated that the fluidity of cement concrete with different coarse aggregate increased in this order: gneiss < limestone < basalt < diabase. The mechanical strengths and shrinkage rate increased obviously with the increasing curing age when the curing age ranged from 7 days to 28 days. However, the mechanical strengths and shrinkage rate trended to a stable value when the increasing curing age increased from 28 days to 56 days. The mechanical strengths with different coarse aggregate increased in this order: diabase < basalt < limestone < gneiss. Meanwhile, the shrinkage rate demonstrated this trend of development: diabase < basalt < limestone < gneiss. The resistance to freeze–thaw cycles of cement concrete decreased with the increasing water–binder ratio. Meanwhile, the resistance to freeze–thaw cycles was closely related to the types of coarse aggregate. Full article
(This article belongs to the Special Issue Interface and Surface Modification for Durable Concretes)
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12 pages, 3275 KiB  
Article
Research on the Thermal Conductivity and Water Resistance of Foamed Phosphogypsum
by Liyu Feng, Kaikai Jin and Hui Wang
Coatings 2021, 11(7), 802; https://doi.org/10.3390/coatings11070802 - 2 Jul 2021
Cited by 15 | Viewed by 2500
Abstract
Phosphogypsum is a kind of solid waste which pollutes the environment without reasonable treatment. The application of phosphogypsum in the field of building materials provides an ideal method to solve this problem. Meanwhile, the phosphogypsum mixed with foam can be used for the [...] Read more.
Phosphogypsum is a kind of solid waste which pollutes the environment without reasonable treatment. The application of phosphogypsum in the field of building materials provides an ideal method to solve this problem. Meanwhile, the phosphogypsum mixed with foam can be used for the thermal insulation of wall materials. This paper aims to study the influence of foam volume and cement content on the thermal conductivity, water resistance coefficient and the mechanical strengths of foamed phosphogypsum. The volume of foam in this study ranged from 0% to 60%. Moreover, the influences of humidity and cement content on the mechanical strengths of phosphogypsum are investigated. Scanning electron microscope and the mercury intrusion porosimetry are used for the microscale research and analysis. Results indicate that the relationships between the parameters (thermal conductivity, water resistance coefficient and mechanical strengths) and foam volume fit well with a negatively correlated linear function. The addition of cement can improve the compactness of phosphogypsum and decrease the diameter and volume of pores. Therefore, the thermal conductivity, water resistance coefficient and mechanical strengths of phosphogypsum are increased by the addition of cement. Full article
(This article belongs to the Special Issue Interface and Surface Modification for Durable Concretes)
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10 pages, 1744 KiB  
Article
Effect of Assembly Unit of Expansive Agents on the Mechanical Performance and Durability of Cement-Based Materials
by Lin Wang, Chunxue Shu, Tiantian Jiao, Yong Han and Hui Wang
Coatings 2021, 11(6), 731; https://doi.org/10.3390/coatings11060731 - 18 Jun 2021
Cited by 4 | Viewed by 2082
Abstract
This paper studies the influence of assembly unit of expansive agents (CaO and calcium sulphoaluminate) on the limited and free compressive strengths, the limited expansion rate, carbonation resistance, chloride ion penetration resistance and corrosion resistance of reinforcement concrete. The dosages of expansive agent [...] Read more.
This paper studies the influence of assembly unit of expansive agents (CaO and calcium sulphoaluminate) on the limited and free compressive strengths, the limited expansion rate, carbonation resistance, chloride ion penetration resistance and corrosion resistance of reinforcement concrete. The dosages of expansive agent were 0%, 3%, 6%, 9%, and 12% by the total amount of cementitious materials. Two kinds of mineral admixture (blast furnace slag and fly ash) were applied in this study. Results show that suitable dosage (lower than or equal to 9%) of double expansion agent with a large amount of mineral admixtures can improve the limited and free compressive strengths. However, when the dosage of the double expansion agent is higher than 9%, the addition of the double expansion agent leads to the reduction of limited and free compressive strengths. The variation of the limit expansion rate reaches the maximum value when the curing age is 14 days. The increasing addition of expansive agents and lower water-binder ratio demonstrate positive effect on the limited expansion rate. Concrete with 60% mineral admixtures (fly ash and ground granulated blast furnace slag) shows lower limited expansion rate and higher compressive strength than the concrete with 50% mineral admixtures. Finally, the incorporation of double expansion agent can improve the resistance to carbonation, chloride ion penetration resistance, anti-corrosion of steel bars and mechanical strengths (the limited and free compressive strengths). Full article
(This article belongs to the Special Issue Interface and Surface Modification for Durable Concretes)
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14 pages, 2745 KiB  
Article
Influence of Lightly Burned MgO on the Mechanical Properties and Anticarbonization of Cement-Based Materials
by Lin Wang, Chao Li, Chunxue Shu, Han Yong, Jianmin Wang and Hui Wang
Coatings 2021, 11(6), 714; https://doi.org/10.3390/coatings11060714 - 15 Jun 2021
Cited by 4 | Viewed by 2157
Abstract
This study aims to study the influence of a lightly burned magnesium oxide (LBMO) expansion agent on the rheological properties (the slump flow, plastic viscosity and variation of shear stress) of cement-based materials. Four different mass contents (i.e., 0%, 3%, 6% and 9%) [...] Read more.
This study aims to study the influence of a lightly burned magnesium oxide (LBMO) expansion agent on the rheological properties (the slump flow, plastic viscosity and variation of shear stress) of cement-based materials. Four different mass contents (i.e., 0%, 3%, 6% and 9%) of LBMO were selected. The following compressive strength and expansion value of the corresponding cement concrete were tested. Cement concrete with two strength grades of 30 MPa and 50 MPa (C30 and C50) was selected. Results indicated that the addition of LBMO can effectively decrease the fluidity and increase the plastic viscosity of fresh cement paste. An optimum dosage (3%) of LBMO is the most advantageous to the compressive strength of cement concrete. The addition of LBMO can increase the expansion rate of cement concrete, thus preventing inside cracks. Moreover, the incorporation of LBMO led to a reduction in the fluidity of the cement paste and an increase in plastic viscosity. The addition of LBMO can increase the expansion rate of cement concrete, thus preventing inside cracks. It can be found that little difference exists in the compressive strength and the expansion rate of cement concrete with strength grades of 30 MPa and 50 MPa. Finally, the increased dosage of LBMO, curing age and compressive strength led to improving the carbonization resistance of cement concrete. Full article
(This article belongs to the Special Issue Interface and Surface Modification for Durable Concretes)
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10 pages, 28601 KiB  
Article
Influence of Rust Inhibitor on the Corrosion Resistance of Reinforcement in Cement Paste with Chloride
by Linchun Zhang, Ailian Zhang, Ke Li, Qian Wang, Junzhe Liu and Hui Wang
Coatings 2021, 11(5), 606; https://doi.org/10.3390/coatings11050606 - 20 May 2021
Cited by 6 | Viewed by 2435
Abstract
The electrical resistance and polarization effect of cement paste containing reinforcement were tested to research the anti-corrosion properties of steel bars in cement paste. Moreover, the microstructure and composition of passivation film and rust on the steel bars were studied. The water–cement ratio [...] Read more.
The electrical resistance and polarization effect of cement paste containing reinforcement were tested to research the anti-corrosion properties of steel bars in cement paste. Moreover, the microstructure and composition of passivation film and rust on the steel bars were studied. The water–cement ratio of the cement paste in this study was 0.3, with 0.5% NaCl, 1% NaNO2, and 1% Benzotriazole, and an assembly unit of 0.5% NaNO2 + 0.5% Benzotriazole by mass of cement was added to the cement to provide a chloride environment. X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM) were applied to research the composition of the passivation film and the microstructure of the cement paste, respectively. The results indicated that the samples with the assembly unit of 0.5% NaNO2 + 0.5% Benzotriazole showed the highest electrical resistance and polarization electrical resistance, while the specimens with 1.0% Benzotriazole showed the lowest electrical resistance and polarization electrical resistance. Moreover, the passivation film of steel bars weakened with increasing distance from the surface of the steel bars. Therefore, the corrosion of steel bars becomes more serious with increasing distance. Finally, the influence of the rust inhibitor on the corrosion resistance of steel bars in the specimens decreased in the following order: 0.5% NaNO2 + 0.5% Benzotriazole >1.0% NaNO2>1.0% Benzotriazole. Full article
(This article belongs to the Special Issue Interface and Surface Modification for Durable Concretes)
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9 pages, 508 KiB  
Article
Life Prediction Model of Mineral Admixture Cement Based-Materials under Early Age CO2-Erosion
by Saisai Wang, Jian Chen and Xiaodong Wen
Coatings 2021, 11(4), 413; https://doi.org/10.3390/coatings11040413 - 1 Apr 2021
Viewed by 1427
Abstract
Most of the existing models of structural life prediction in early carbonized environment are based on accelerated erosion after standard 28 days of cement-based materials, while cement-based materials in actual engineering are often exposed to air too early. These result in large predictions [...] Read more.
Most of the existing models of structural life prediction in early carbonized environment are based on accelerated erosion after standard 28 days of cement-based materials, while cement-based materials in actual engineering are often exposed to air too early. These result in large predictions of the life expectancy of mineral-admixture cement-based materials under early CO2-erosion and affecting the safe use of structures. To this end, different types of mineral doped cement-based material test pieces are formed, and early CO2-erosion experimental tests are carried out. On the basis of the analysis of the existing model, the influence coefficient of CO2-erosion of the mineral admixture Km is introduced, the relevant function is given, and the life prediction model of the mineral admixture cement-based material under the early CO2-erosion is established and the model parameters are determined by using the particle group algorithm (PSO). It has good engineering applicability and guiding significance. Full article
(This article belongs to the Special Issue Interface and Surface Modification for Durable Concretes)
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14 pages, 2681 KiB  
Article
Experimental Analysis of Reinforcement Rust in Cement under Corrosive Environment
by Xiaozhen Li, Hui Wang, Jianmin Wang and Junzhe Liu
Coatings 2021, 11(2), 241; https://doi.org/10.3390/coatings11020241 - 18 Feb 2021
Cited by 3 | Viewed by 3034
Abstract
In this work, the microstructure characteristics of corrosion products of reinforcement under a corrosive environment with chloride, carbonation and the combination of chloride-carbonization were studied by x-ray photoelectron spectroscopy (XPS) and scanning electron microscopy/energy spectroscopy (SEM-EDX). The results indicate that the outside of [...] Read more.
In this work, the microstructure characteristics of corrosion products of reinforcement under a corrosive environment with chloride, carbonation and the combination of chloride-carbonization were studied by x-ray photoelectron spectroscopy (XPS) and scanning electron microscopy/energy spectroscopy (SEM-EDX). The results indicate that the outside of the passivation film reacts with the cement slurry to produce Fe–SiO4 in all three corrosive environments. The inner side is not completely corroded. The morphology of the corrosion is different in the three environments. In a chloride environment, corrosion products have obvious cracks, and the local layered structure is dense. In a carbonation environment, the surface of the steel corrosion shows a uniform granular structure and loose texture. With the combination of chloride and combination, the surface of the structural layer of steel corrosion was uneven and accompanied by protrusions, cracking and spalling occurred. The composition of the corrosion substances in the three corrosion environments are mainly composed of FeO, Fe3O4, Fe2O3 and Fe–SiO4. The content of iron oxide increases from a chloride salt, carbonization to the composite environment, indicating that the corrosion degree intensifies successively. Full article
(This article belongs to the Special Issue Interface and Surface Modification for Durable Concretes)
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9 pages, 1875 KiB  
Article
Influence of NaCl Freeze Thaw Cycles and Cyclic Loading on the Mechanical Performance and Permeability of Sulphoaluminate Cement Reactive Powder Concrete
by Xinghua Hong, Hui Wang and Feiting Shi
Coatings 2020, 10(12), 1227; https://doi.org/10.3390/coatings10121227 - 16 Dec 2020
Cited by 25 | Viewed by 2328
Abstract
This paper aimed to investigate the coupling effects of NaCl freeze–thaw cycles and cyclic loading on the mechanical performance and permeability of sulphoaluminate cement reactive powder concrete (RPC). Firstly, the compressive and flexural strengths of sulphoaluminate cement RPC were investigated. Then, the chloride [...] Read more.
This paper aimed to investigate the coupling effects of NaCl freeze–thaw cycles and cyclic loading on the mechanical performance and permeability of sulphoaluminate cement reactive powder concrete (RPC). Firstly, the compressive and flexural strengths of sulphoaluminate cement RPC were investigated. Then, the chloride ion permeability, mechanical strengths (compressive and flexural strengths) and mass loss were determined. Results indicated that the increased steel fibers content and curing age played positive roles in the mechanical strengths. The threshold values of steel fibers and curing age were 3.0% and 14 days. Sulphoaluminate cement RPC with early curing age (5 h) showed relatively high mechanical strengths: flexural strength (8.69~17.51 MPa), and compressive strength (34.1~38.5 MPa). The mass loss, the chloride migration coefficient, and the compressive strength loss increased linearly with NaCl freeze–thaw cycles. Meanwhile, the flexural strength loss increased with the exponential function. The relative dynamic modulus of elasticity of specimens decreased linearly with the increased freeze–thaw cycles. Finally, it was observed from this paper, cyclic loading demonstrated negative roles on the mechanical strengths and resistance to chloride penetration. Full article
(This article belongs to the Special Issue Interface and Surface Modification for Durable Concretes)
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23 pages, 12211 KiB  
Article
Research on the Chloride Ion Penetration Resistance of Magnesium Phosphate Cement (MPC) Material as Coating for Reinforced Concrete Structures
by Yubing Du, Peiwei Gao, Jianming Yang and Feiting Shi
Coatings 2020, 10(12), 1145; https://doi.org/10.3390/coatings10121145 - 24 Nov 2020
Cited by 19 | Viewed by 2913
Abstract
This study focuses on the chloride ion penetration resistance of a magnesium phosphate cement (MPC)-based composite material coating on the surface of silicate material. By means of electrical flux method and electric acceleration corrosion tests, the anti-chlorine ion permeation and reinforcement properties of [...] Read more.
This study focuses on the chloride ion penetration resistance of a magnesium phosphate cement (MPC)-based composite material coating on the surface of silicate material. By means of electrical flux method and electric acceleration corrosion tests, the anti-chlorine ion permeation and reinforcement properties of MPC-based materials and Portland cement (OPC) mortar were compared and analyzed. The experimental results show that the electrical flux of the hardened body of the MPC-based material is much lower than that of the Portland cement mortar, and the electrical flux of the hardened body of the MPC mortar can be obviously reduced by adding silica-fume (SF) and fly ash (FA), which, when combined in a suitable proportion, will make the MPC’s hardened body more dense and impermeable. The addition of short cut fibers increases the number of pores, the pore size, and the electrical flux of the cement mortar’s hardened body. The adverse effects of the three fibers on the permeability of the MPC mortar against chlorine ions were as follows: polyvinyl alcohol fiber > glass fiber > basalt fiber. The electrical flux of MPC mortar or MPC paste coated on the surface of the OPC mortar was greatly reduced. Compared with silicate mortar, the MPC-based material has excellent protective performance under the condition of accelerated corrosion. Full article
(This article belongs to the Special Issue Interface and Surface Modification for Durable Concretes)
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9 pages, 1748 KiB  
Article
Research on the Influence of Carbonation on the Content and State of Chloride Ions and the Following Corrosion Resistance of Steel Bars in Cement Paste
by Hui Wang, Ailian Zhang, Linchun Zhang, Junzhe Liu, Yan Han and Jianmin Wang
Coatings 2020, 10(11), 1071; https://doi.org/10.3390/coatings10111071 - 7 Nov 2020
Cited by 14 | Viewed by 1936
Abstract
In this paper, the changes of free chloride ion concentration and bound chloride concentration in cement paste with different total and proportion of mineral admixtures under carbonation were studied. Moreover, the following corrosion resistance of steel bars buried in cement paste under carbonation [...] Read more.
In this paper, the changes of free chloride ion concentration and bound chloride concentration in cement paste with different total and proportion of mineral admixtures under carbonation were studied. Moreover, the following corrosion resistance of steel bars buried in cement paste under carbonation was researched by testing the electrical resistance and alternating current (AC) impedance spectroscopy of reinforced cement paste. Results indicated that fly ash and granulated blast furnace slag powder with the content less than 20% by mass ratio of total binder hindered the solidification of chloride ions in cement-based materials, and blast furnace slag powder with the content higher than 20% promoted the solidification of chloride ions in cement paste. The carbonation effect was able to decrease the amount of solidified chloride ion and increase the amount of free chloride ions leading to accelerating the corrosion of reinforcement. Meanwhile, the blast furnace slag powder with the content higher than 20% could effectively promote the corrosion resistance of steel bars. Full article
(This article belongs to the Special Issue Interface and Surface Modification for Durable Concretes)
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