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25 pages, 32544 KB

Open AccessArticle

Direct Shear Behavior of Silty-Loam–Concrete Interfaces Subjected to Freeze–Thaw Cycling: An Experimental and DIC Investigation

by Bin Xu, Jialing Liu, Yue Liang, Jianlu Zhang, Xiaoming Hu, Yi Xu, Gaorui Wu and Peng Duan

Buildings 2026, 16(18), 3567; https://doi.org/10.3390/buildings16183567 - 8 Sep 2026

Viewed by 168

Abstract

Freeze–thaw cycling can alter soil–structure interface response in seasonally frozen regions. This study investigated the direct-shear behavior of a commercially sourced silty-loam–concrete interface subjected to sealed freeze–thaw cycling. A 25-condition mixed-level design based on the standard L25(5⁶) orthogonal array (25 runs [...] Read more.

Freeze–thaw cycling can alter soil–structure interface response in seasonally frozen regions. This study investigated the direct-shear behavior of a commercially sourced silty-loam–concrete interface subjected to sealed freeze–thaw cycling. A 25-condition mixed-level design based on the standard L25(5⁶) orthogonal array (25 runs with six available five-level columns) considered normal stress, nominal interface roughness, moisture content, and freeze–thaw-cycle number; each main condition was tested once, so the results are interpreted descriptively. Shear strength and shear-induced vertical contraction were measured, and digital image correlation (DIC) was used to characterize surface deformation localization. The level-wise mean shear strength increased with normal stress and approximately linearly with roughness. It changed little between 14% and 18% moisture content and decreased at 22% and 26%; the measured plastic limit was 19.2%. With increasing freeze–thaw cycles, the level-wise mean strength decreased to three cycles, then recovered and approached stabilization. These results provide laboratory-scale evidence under the tested closed-system conditions rather than directly transferable pile-design parameters. Full article

(This article belongs to the Special Issue Research on Durability and Aging on Materials and Structures in Buildings)

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21 pages, 26501 KB

Open AccessArticle

Surface Pre-Coating of Fly Ash Ceramsite for Interfacial Microstructure Evolution and Mechanical Enhancement of Lightweight Concrete

by Hua Wei, Anyi Chen, Chunhe Li and Hao Lu

Buildings 2026, 16(17), 3495; https://doi.org/10.3390/buildings16173495 - 2 Sep 2026

Viewed by 211

Abstract

The widespread application of fly ash ceramsite as a lightweight aggregate in high-performance concrete is restricted by its inherent defects, including high porosity, high water absorption rate and weak interfacial transition zone (ITZ). In this study, a surface pre-treatment strategy is proposed, in [...] Read more.

The widespread application of fly ash ceramsite as a lightweight aggregate in high-performance concrete is restricted by its inherent defects, including high porosity, high water absorption rate and weak interfacial transition zone (ITZ). In this study, a surface pre-treatment strategy is proposed, in which the ceramsite granules are pre-coated prior to mixing, followed by concrete preparation with the modified aggregates. A pre-coating formulation of micro–nano silica fume and modified acrylate emulsion was applied to improve the interfacial characteristics and mechanical/durability performance. The results show that the coating treatment improved 28-day compressive, flexural–tensile, and axial tensile strengths by 21.2%, 16.0%, and 20.6%, respectively, along with the elastic modulus and ultimate tensile strain. The coated concrete achieved an impermeability grade exceeding W14, retained over 85% of relative dynamic elastic modulus after 150 freeze–thaw cycles, and maintained compressive strength above 90.0% after 20 wetting–drying cycles, with a corresponding relative dynamic elastic modulus of 67.24%. Microstructural observation, pore parameter analysis, and microzone mechanical testing were performed to reveal the underlying mechanisms. The performance improvement is mainly attributed to the strengthening of the traditionally weak interfacial transition zone (ITZ). Additionally, the coating refines the pore structure, stabilizes its distribution, and acts as a physical barrier, further enhancing resistance to freeze–thaw and wetting–drying cycles. Full article

(This article belongs to the Special Issue Research on Durability and Aging on Materials and Structures in Buildings)

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32 pages, 41387 KB

Open AccessArticle

Engineering Assessment of Structural Deterioration and Preservation Challenges in a Corroded Reinforced Concrete Building Exposed to a Marine Environment

by Charis Apostolopoulos, Apostolos Linos Apostolopoulos and Alkiviadis Apostolopoulos

Buildings 2026, 16(15), 2997; https://doi.org/10.3390/buildings16152997 - 28 Jul 2026

Viewed by 467

Abstract

The preservation of twentieth-century reinforced concrete buildings increasingly requires the integration of structural engineering assessment with heritage conservation principles. Although the deterioration mechanisms of reinforced concrete in marine environments have been extensively investigated, relatively few studies have examined how advanced material degradation affects [...] Read more.

The preservation of twentieth-century reinforced concrete buildings increasingly requires the integration of structural engineering assessment with heritage conservation principles. Although the deterioration mechanisms of reinforced concrete in marine environments have been extensively investigated, relatively few studies have examined how advanced material degradation affects the technical feasibility of preserving modern reinforced concrete heritage structures. This study addresses this gap through the structural assessment of the Patras Port Authority Building (OLPA), a reinforced concrete building constructed in the early 1970s and exposed for more than five decades to an aggressive coastal environment, providing the engineering basis for determining whether a complete code-based structural assessment is justified in accordance with KAN.EPE. and EN ISO 13822. A comprehensive inspection and testing program was carried out, including visual inspection, crack mapping, concrete core testing, carbonation-depth measurements, pH determination, chloride-content analysis, half-cell potential measurements, electrical resistivity measurements, and selective exposure of reinforcement. The engineering assessment revealed extensive deterioration of the structural system, including low concrete strength (approximately C8/10), carbonation exceeding the concrete cover, pH values between 7 and 8, chloride concentrations ranging from 0.0377% to 0.8975% by cement mass, and severe reinforcement corrosion. The measured average cross-sectional loss reached 34.5% for longitudinal reinforcement and 65.6% for transverse reinforcement (stirrups), accompanied by significant reductions in mechanical properties and ductility. It should be noted that concrete samples for chloride determination were collected at depths well beyond the reinforcement level. Additional deficiencies associated with inadequate confinement reinforcement, outdated seismic detailing, previous earthquake damage, cracking in columns and shear walls, and uncertainty regarding the geometry and condition of the foundation system further increase structural vulnerability. The engineering assessment indicates that the combined effects of long-term environmental exposure, corrosion-induced deterioration, obsolete design provisions, and existing structural deficiencies substantially reduce the reliability and seismic performance of the load-bearing system. Within this context, the study examines the implications of advanced deterioration for the preservation of reinforced concrete heritage buildings and proposes an integrated assessment framework that combines structural safety, durability, material integrity, intervention feasibility, and heritage significance. The proposed approach contributes to a more comprehensive engineering-based methodology for evaluating preservation strategies for aging reinforced concrete buildings exposed to aggressive marine environments. These findings also raise important concerns regarding the technical feasibility of preserving ageing reinforced concrete buildings located in highly seismic regions, where ensuring structural safety may require the introduction of new load-bearing elements together with the replacement of a substantial portion of the already deteriorated original material. Full article

(This article belongs to the Special Issue Research on Durability and Aging on Materials and Structures in Buildings)

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24 pages, 2958 KB

Open AccessArticle

Optimization of Heat Treatment Parameters in CA-50 Steel Rebars: Impact on Microstructure and Corrosion Resistance

by Thiago Barros, José Silva, Aureliano Santos, Tiago Santos, Humberto Almeida-Silva, Samuel Castro-Lopes and Romildo Berenguer

Buildings 2026, 16(13), 2598; https://doi.org/10.3390/buildings16132598 - 29 Jun 2026

Viewed by 419

Abstract

This study evaluates the influence of heat treatment parameters on the microstructure and corrosion resistance of CA-50 low-carbon steel rebars (0.20–0.25 wt.% C) processed by the Thermex route. A full 2³ factorial design combined with response surface methodology was employed to investigate [...] Read more.

This study evaluates the influence of heat treatment parameters on the microstructure and corrosion resistance of CA-50 low-carbon steel rebars (0.20–0.25 wt.% C) processed by the Thermex route. A full 2³ factorial design combined with response surface methodology was employed to investigate the effects of residence time (15–35 min), heating rate (5–15 °C/min), and soaking temperature (730–850 °C). Corrosion behavior was assessed by linear potentiodynamic polarization and electrochemical impedance spectroscopy in 3.5 wt.% NaCl solution. The corrosion potential (E_corr) varied between −520.6 and −618.1 mV, with optimal values close to −535 mV obtained at low heating rates and short residence times. Polarization resistance (R_p) ranged from 70.4 kΩ to 166.6 MΩ, with the highest value observed for treatment at 790 °C, 10 °C/min, and 25 min, representing an increase of more than fivefold compared to the reference condition. Statistical analysis revealed that residence time and heating rate significantly affect E_corr (R² = 96.8%), while R_p is governed exclusively by residence time (p = 0.004). Microstructural analysis correlated refined and homogeneous ferritic–pearlitic structures with improved corrosion resistance, whereas grain coarsening led to severe electrochemical degradation. Full article

(This article belongs to the Special Issue Research on Durability and Aging on Materials and Structures in Buildings)

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17 pages, 6180 KB

Open AccessArticle

Mechanical Performance and Sustainability Assessment of Mortar Incorporating Recycled Chicken Bone Powder

by Kyu-Chang Kim, Sung-Mu Han and Jun-Mo Yang

Buildings 2026, 16(11), 2256; https://doi.org/10.3390/buildings16112256 - 3 Jun 2026

Viewed by 547

Abstract

This study investigated the feasibility of using hydroxyapatite (HAp) derived from pyrolyzed waste chicken bones as a sustainable cement replacement material for cement mortar. Commercial tricalcium phosphate (TCP), which belongs to the same calcium phosphate family but possesses distinct crystalline characteristics, was used [...] Read more.

This study investigated the feasibility of using hydroxyapatite (HAp) derived from pyrolyzed waste chicken bones as a sustainable cement replacement material for cement mortar. Commercial tricalcium phosphate (TCP), which belongs to the same calcium phosphate family but possesses distinct crystalline characteristics, was used as a comparative material. HAp and TCP were incorporated as partial cement replacements at 2, 5, 10, and 20% by weight, and the workability, compressive strength, flexural strength, microstructure, and CO₂ emission characteristics of the resulting mortars were evaluated. The results showed that low replacement ratios improved early-age strength owing to the micro-filler effect of fine calcium phosphate particles. In particular, the HAp mixtures exhibited superior long-term performance compared with the TCP mixtures, with the 2% HAp mixture achieving the highest compressive strength of 54.5 MPa at 56 days. Flexural strength results showed a similar trend, with HAp effectively suppressing microcrack propagation through improved matrix densification and interfacial bonding. However, replacement ratios exceeding 10% reduced mechanical performance due to cement dilution, increased porosity, and particle agglomeration. SEM observations confirmed that HAp replacement levels of 2–5% densified the mortar matrix, whereas excessive replacement caused localized agglomeration and microstructural defects. The carbon emission assessment indicated that pyrolysis reduced direct CO₂ emissions compared with incineration by immobilizing part of the carbon in solid char; however, laboratory-scale pyrolysis increased total emissions because of high electricity consumption. Nevertheless, process integration with cement clinker production could enable waste valorization and carbon reduction by utilizing existing high-temperature kiln systems. Overall, chicken bone-derived HAp–carbon composite demonstrated strong potential as an eco-friendly cement replacement material, with an optimal replacement ratio of 5% or less. Full article

(This article belongs to the Special Issue Research on Durability and Aging on Materials and Structures in Buildings)

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29 pages, 9499 KB

Open AccessArticle

Soil-Specific Effects on the Strengthening Mechanism and Microstructural Evolution of Alkali-Activated Red Mud–Slag Solidified Soil: Clay vs. Silt

by Xinyu Yang, Zhirong Jia, Yaoxi Han, Xuekun Jiang, Jiantong Wu, Xuejing Wang and Tian Su

Buildings 2026, 16(9), 1823; https://doi.org/10.3390/buildings16091823 - 3 May 2026

Viewed by 597

Abstract

The performance of fluid solidified soil (FSS) depends on the curing agents as well as, to a great extent, the soil type. Currently, most studies focus on a single type of soil, which limits the applicability of research findings to practical engineering scenarios [...] Read more.

The performance of fluid solidified soil (FSS) depends on the curing agents as well as, to a great extent, the soil type. Currently, most studies focus on a single type of soil, which limits the applicability of research findings to practical engineering scenarios involving diverse soil conditions. To address this issue, this study selects two representative soil types—clay (CL) and silt (ML)—and employs alkali-activated red mud–slag as curing agent to prepare FSS. Laboratory experiments were conducted to evaluate the influence of soil type on the engineering properties and durability of the specimens. Specifically, the effects of soil type on flowability and unconfined compressive strength were comparatively analyzed. Durability was assessed through shrinkage, water stability and wet–dry cycle tests. Furthermore, X-ray diffraction, Thermogravimetric, Fourier transform infrared spectroscopy, field emission scanning electron microscopy and Brunauer–Emmett–Teller were utilized to characterize the microstructure and hydration products of the samples. The results indicate that an increasing proportion of ML leads to a decrease in overall flowability but a significant enhancement in late-age unconfined compressive strength. Meanwhile, the drying shrinkage of ML is gradually reduced, and both water stability and resistance to wet–dry cycles are correspondingly improved. Microstructural analyses reveal that the primary hydration product across all samples is C-(A)-S-H gel. Samples with higher ML content exhibit a denser structure and an increased volume of hydration products, which is consistent with the observed macroscopic performance trends. Full article

(This article belongs to the Special Issue Research on Durability and Aging on Materials and Structures in Buildings)

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16 pages, 2725 KB

Open AccessArticle

Comparative Analysis of Freeze–Thaw Effects on the Parallel-to-Grain Compressive Properties of Bamboo and Chinese Fir

by Kang Zhao and Yang Wei

Buildings 2026, 16(2), 291; https://doi.org/10.3390/buildings16020291 - 9 Jan 2026

Viewed by 584

Abstract

To evaluate the application potential of bamboo in cold regions, this study systematically compared the differences in the effects of freeze–thaw cycles on the longitudinal compressive properties of moso bamboo (Phyllostachys edulis) and Chinese fir (Cunninghamia lanceolata). By subjecting [...] Read more.

To evaluate the application potential of bamboo in cold regions, this study systematically compared the differences in the effects of freeze–thaw cycles on the longitudinal compressive properties of moso bamboo (Phyllostachys edulis) and Chinese fir (Cunninghamia lanceolata). By subjecting the materials to 0, 5, and 10 standard freeze–thaw cycles, the evolution patterns were analyzed from three aspects: mechanical properties, failure modes, and apparent color. The results show that bamboo exhibits significantly superior freeze–thaw resistance: after 10 cycles, bamboo retained 95.4% of its compressive strength (decreasing from 50.2 MPa to 47.9 MPa), whereas the strength of Chinese fir decreased by 14.2% (from 46.7 MPa to 40.0 MPa). The elastic modulus of bamboo remained stable, while that of Chinese fir decreased by 30.86%. Load–displacement curves revealed that bamboo displayed a ductile plateau after failure, whereas Chinese fir exhibited a linear drop-off. Analysis of failure modes further highlighted the intrinsic differences between the materials: bamboo primarily underwent progressive buckling of fiber bundles, forming typical accordion-like folds; Chinese fir mainly showed brittle failures such as end crushing and longitudinal splitting. Color characterization indicated that the lightness index L of the bamboo outer skin (bamboo green) decreased by 26.1%, while the chromaticity indices a (red) and b* (yellow) increased significantly, showing the most notable changes; the color of Chinese fir and the bamboo inner skin (bamboo yellow) remained relatively stable. This study demonstrates that natural bamboo outperforms Chinese fir in terms of frost resistance, toughness, and strength retention in the short term. The findings provide important experimental evidence and design references for promoting the application of bamboo in engineering projects in cold regions. Full article

(This article belongs to the Special Issue Research on Durability and Aging on Materials and Structures in Buildings)

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11 pages, 2262 KB

Open AccessArticle

Application of Resistometric Sensors in Investigation of Zinc Corrosion in Simulated Concrete Environments

by Matěj Reiser, Milan Kouřil, Pietro Forcellese and Tiziano Bellezze

Buildings 2025, 15(4), 635; https://doi.org/10.3390/buildings15040635 - 19 Feb 2025

Cited by 2 | Viewed by 1081

Abstract

The aim of this paper was to investigate the corrosion behaviour of zinc in simulated concrete solutions using resistometric sensors and to describe the kinetics of zinc corrosion. The sensors provide corrosion data information in real time; thus, it is a useful technique [...] Read more.

The aim of this paper was to investigate the corrosion behaviour of zinc in simulated concrete solutions using resistometric sensors and to describe the kinetics of zinc corrosion. The sensors provide corrosion data information in real time; thus, it is a useful technique for observing zinc corrosion behaviour in concrete environments. The replacement of carbon steel rebar by galvanized steel in concrete is a discussable topic with contradictory results in the literature presented in the introduction. In our case, zinc resistometric sensors were used, and they showed results in good agreement with other techniques, such as corrosion potential monitoring and EIS measurements. According to our results, zinc is able to passivate in a simulated concrete solution and even in a simulated carbonated solution. The corrosion rate was reduced by almost 40 times, during the active to passive transition. The zinc remains passive even in simulated concrete solutions contaminated with low levels of chloride ions up to 0.9 wt.%. Full article

(This article belongs to the Special Issue Research on Durability and Aging on Materials and Structures in Buildings)

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20 pages, 2677 KB

Open AccessArticle

Workability of Nanomodified Self-Compacting Geopolymer Concrete Based on Response Surface Method

by Yong-Hua Tian, Jia-Cheng Tao, Tao Luo and Li Li

Buildings 2024, 14(11), 3610; https://doi.org/10.3390/buildings14113610 - 13 Nov 2024

Cited by 7 | Viewed by 2173

Abstract

Geopolymer concrete is more low-carbon and environmentally friendly than Portland cement concrete. Nanoparticle modification can help to improve the mechanical and durability performance of concrete, but due to its large specific surface area and high activity, it may deteriorate its workability. However, there [...] Read more.

Geopolymer concrete is more low-carbon and environmentally friendly than Portland cement concrete. Nanoparticle modification can help to improve the mechanical and durability performance of concrete, but due to its large specific surface area and high activity, it may deteriorate its workability. However, there is currently limited research on the effect of nanomodification on the workability of freshly mixed self-compacting geopolymer concrete (SCGC). This article conducted SCGC workability experiments using the response surface methodology, which included 29 different mixtures. The effects of nano-silica (NS), nano-calcium carbonate (NC), alkali content (N/B), and water cement ratio (W/B) on the workability of SCGC were studied. The experimental results show that the addition of NS and NC can reduce the slump expansion of SCGC, and the combination of the two significantly increases the amplitude of slump expansion with the change in nanomaterial content. An increase in N/B will reduce the expansion time and clearance value of SCGC. As N/B increases from 4% to 4.4%, the slump extension of SCGC decreases, and with a further increase in N/B, the slump extension increases significantly to 68.1 cm, which means that the slump extension of SCGC increases by 9.5% as N/B increases from 4.4 to 5. This study can provide a reference for optimizing the fresh performance of geopolymer concrete and improving the mechanism of nanomaterial-modified geopolymer concrete. Full article

(This article belongs to the Special Issue Research on Durability and Aging on Materials and Structures in Buildings)

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19 pages, 22993 KB

Open AccessArticle

Water Resistance of Acrylic Adhesive Tapes for Rooftop Fastening

by Klára V. Machalická, Petr Sejkot, Miroslav Vokáč, Petr Pokorný and Vera Obradović

Buildings 2024, 14(6), 1636; https://doi.org/10.3390/buildings14061636 - 3 Jun 2024

Cited by 3 | Viewed by 2502

Abstract

Rooftop solar modules are usually held in place by racks or frames that are mechanically attached to a roof structure and/or by heavyweight, ballasted footing mounts. These mounts ensure that the panel system remains in position against wind load. However, mechanical connectors create [...] Read more.

Rooftop solar modules are usually held in place by racks or frames that are mechanically attached to a roof structure and/or by heavyweight, ballasted footing mounts. These mounts ensure that the panel system remains in position against wind load. However, mechanical connectors create penetrations into the water-resistant layer of the roof, whereas ballasted footing mounts cause a significant additional load on the load-bearing structure of roof. For these reasons, adhesive connection seems to be a beneficial solution. Acrylic adhesive tapes, marked as VHB^TM, may provide sufficient strength, and they have no need for mechanical fasteners or ballast. Acrylic adhesive tapes also provide a comfortable, fast, and efficient bonding process with no curing compared to liquid adhesives. On the other hand, resistance to water at load-bearing joints has not been sufficiently studied yet and could be critical for connections exposed to the outdoor environment. The present study aims at the determination of water resistance and durability of the VHB^TM tapes from the GPH series, which are typically used to bond a variety of substrates including many metals. The mechanical properties and failure modes are compared for the specimens before and after a 21-day immersion in water. A significant reduction in strength was observed, depending on the substrate material. The study of chemical changes in the acrylic tape and in its leachate through infrared spectroscopy (FT-IR), X-ray fluorescence, and X-ray diffraction analyses clarified the reduction in mechanical properties. The selected VHB^TM tape demonstrated strong resistance to the effects of water. However, the overall strength of the joint after immersion was significantly impacted by the decrease in adhesion to a specific substrate. Full article

(This article belongs to the Special Issue Research on Durability and Aging on Materials and Structures in Buildings)

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26 pages, 12504 KB

Open AccessArticle

Corrosion Properties and Bond Strength in Normal Strength Concrete of Al₂O₃ Plasma-Sprayed Plain Bars with ZrCC/Organofunctional Silane Coating

by Petr Pokorný, Nikola Prodanovic, Karel Hurtig, Veronika Steinerová, Jaroslav Fojt, Marek Janata and Vlastimil Brožek

Buildings 2024, 14(6), 1543; https://doi.org/10.3390/buildings14061543 - 26 May 2024

Cited by 4 | Viewed by 2104

Abstract

In this study, the corrosion properties of plasma-sprayed Al₂O₃ coating (APSS) with a topcoat of zirconium-based conversion coating (ZrCC) and organofunctional silane coating (3-glycidyloxypropyltrimethoxysilane; GPTMS) on carbon steel are investigated in detail. Additionally, the bond strength of plain steel bars [...] Read more.

In this study, the corrosion properties of plasma-sprayed Al₂O₃ coating (APSS) with a topcoat of zirconium-based conversion coating (ZrCC) and organofunctional silane coating (3-glycidyloxypropyltrimethoxysilane; GPTMS) on carbon steel are investigated in detail. Additionally, the bond strength of plain steel bars coated with this system in normal strength concrete are newly tested. The APSS coating exhibits significant porosity, with unfavourable open pores limiting the barrier protection effect. In contrast, the surface roughness (R_a) significantly increases, improving the bond strength between steel bars and concrete. Such increase in carbon steel roughness improves bond strength in concrete. The synergic application of ZrCC and GPTMS topcoats significantly enhances the corrosion resistance of the base coat (inhibition effect). The character of the GPTMS coating increases the wettability of the APSS coating, which further positively contributes to bond strength between plain bars and concrete. It is demonstrated that when the ZrCC topcoat is applied without GPTMS, the corrosion resistance increases insignificantly and the surface wettability decreases, negatively affecting bond strength in comparison with carbon steel coated using an APSS base coat only. Full article

(This article belongs to the Special Issue Research on Durability and Aging on Materials and Structures in Buildings)

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13 pages, 4315 KB

Open AccessArticle

Degradation Effect of Moisture on Mechanical Properties of Kevlar/PVB Composites with TiO₂ Nanoparticles

by Vera Obradović, Petr Sejkot, Adam Zabloudil, Klára V. Machalická and Miroslav Vokáč

Buildings 2024, 14(2), 409; https://doi.org/10.3390/buildings14020409 - 2 Feb 2024

Cited by 5 | Viewed by 4999

Abstract

Kevlar fibers are widely used for industrial and military purposes due to their remarkable mechanical properties, such as their high tenacity and high strength-to-weight ratio. In this study, two-layered Kevlar composite specimens were impregnated with 10 wt.% poly (vinyl butyral)/ethanol solution which contained [...] Read more.

Kevlar fibers are widely used for industrial and military purposes due to their remarkable mechanical properties, such as their high tenacity and high strength-to-weight ratio. In this study, two-layered Kevlar composite specimens were impregnated with 10 wt.% poly (vinyl butyral)/ethanol solution which contained TiO₂ nanoparticles as reinforcement. The concentrations of the nanoparticles were 1 wt.% or 2 wt.% with respect to the poly (vinyl butyral), PVB. The single-axial tensile test and three-point bending test of the Kevlar/PVB composites have been performed according to the ASTM D 3039 and ASTM D 790-03 standards, respectively. The tensile and bending properties of the dry and wet Kevlar/PVB composite specimens after a 56-day immersion are examined in this work. Upon the addition of the 2 wt.% TiO₂ nanoparticles, the tensile strength and modulus of the dry specimens without reinforcement were increased by 39.8% and 24.3%, respectively. All the submerged specimens’ tensile and flexural property values were lower than those of the dry specimens. After comparing the wet composite specimens to their dry counterparts, the percentage decrease in tensile strength was approximately 20%. The wet Kevlar/PVB specimens with no TiO₂ reinforcement showed the greatest reduction in bending strength, 61.4% less than for the dry Kevlar/PVB specimens, due to the degradation of the PVB matrix. In addition, a numerical simulation of the three-point bending test was carried out in Abaqus. Full article

(This article belongs to the Special Issue Research on Durability and Aging on Materials and Structures in Buildings)

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16 pages, 5681 KB

Open AccessArticle

Response of Reinforced Concrete Beams under the Combined Effect of Cyclic Loading and Carbonation

by Linxuan Zhu, Zhijun Zhou, Chaoran Chen and Kangchao Wang

Buildings 2023, 13(10), 2403; https://doi.org/10.3390/buildings13102403 - 22 Sep 2023

Cited by 1 | Viewed by 2239

Abstract

To compare the deterioration mechanism of reinforced concrete beams between the combined effect of cyclic loading and carbonation and the sum of both individual factors, an optimized test procedure was introduced in this study. The macroscopic and microscopic results showed that the decrease [...] Read more.

To compare the deterioration mechanism of reinforced concrete beams between the combined effect of cyclic loading and carbonation and the sum of both individual factors, an optimized test procedure was introduced in this study. The macroscopic and microscopic results showed that the decrease in carbonation resistance of concrete could be attributed to the changes in pore structures and crack patterns introduced by cyclic loading. However, the carbonation process of flexural tensile concrete corresponding to different test procedures presented different trends. It indicated that the combined action of carbonation and fatigue damage was more serious than the damage caused by the effect of superposition. Finally, a theoretical carbonation model of concrete subjected to the combined damage was proposed and validated by comparing it with previous experimental results. The research findings are significant for improving the accuracy of evaluation of residual service life of reinforced concrete bridges and early warning of durability protection. Full article

(This article belongs to the Special Issue Research on Durability and Aging on Materials and Structures in Buildings)

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Jump to: Research

25 pages, 8923 KB

Open AccessReview

Mechanisms and Protection Strategies for Concrete Degradation Under Magnesium Salt Environment: A Review

by Xiaopeng Shang, Xuetao Yue, Lin Pan and Jingliang Dong

Buildings 2026, 16(2), 264; https://doi.org/10.3390/buildings16020264 - 7 Jan 2026

Cited by 7 | Viewed by 1373

Abstract

Concrete structures suffering from Mg²⁺ environments may suffer severe damage, which mainly has something to do with the coupled effect among Cl⁻, SO₄²⁻, and Mg²⁺. Based on a systematic review of Web of Science and [...] Read more.

Concrete structures suffering from Mg²⁺ environments may suffer severe damage, which mainly has something to do with the coupled effect among Cl⁻, SO₄²⁻, and Mg²⁺. Based on a systematic review of Web of Science and Scopus database (2000–2025), we first summarized the migration behavior, reaction paths, and interaction mechanism of Cl⁻, SO₄²⁻, and Mg²⁺ in cementitious matrices. Secondly, from the perspective of Cl⁻ cyclic adsorption–desorption breaking the passivation film of steel bars, SO₄²⁻ generating expansion products leads to crack expansion, then Mg²⁺ decalcifies C-S-H and transforms into M-S-H; we analyzed the main damage mechanisms, respectively. In addition, under the coexistence conditions of three kinds of ions, the “fixation–substitution–redissolution” process and “crack–transport” coupling positive feedback mechanism further increase the development rate of damage. Then, some anti-corrosion measures, such as mineral admixtures, functional chemical admixtures, fiber reinforcements, surface coatings, and new binder systems, are summarized, and the pros and cons of different anti-corrosion technologies are compared and evaluated. Lastly, from two aspects of simulation prediction for the coupled corrosion damage mechanism and service life prediction, respectively, we have critically evaluated the advances and problems existing in the current research on the aspects of ion migration-reaction coupled models, multi-physics coupled frameworks, phase-field methods, etc. We found that there is still much work to be conducted in three respects: deepening mechanism understanding, improving prediction precision, and strengthening the connection between laboratory test results and actual projects, so as to provide theoretical basis and technical support for the durability design and anti-corrosion strategies of concrete in complex Mg²⁺ environments. Full article

(This article belongs to the Special Issue Research on Durability and Aging on Materials and Structures in Buildings)

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53 pages, 13665 KB

Open AccessReview

Predicted Corrosion Performance of Organofunctional Silane Coated Steel Reinforcement for Concrete Structures: An Overview

by Petr Pokorný and Milan Kouřil

Buildings 2024, 14(6), 1756; https://doi.org/10.3390/buildings14061756 - 11 Jun 2024

Cited by 11 | Viewed by 5577

Abstract

This article provides a comprehensive overview of the potential use of organofunctional silane coatings in the corrosion protection of concrete reinforcement in close relation to other commercially used coating technologies—i.e., epoxy coatings and bath hot-dip galvanizing coatings. The application technology of the steel [...] Read more.

This article provides a comprehensive overview of the potential use of organofunctional silane coatings in the corrosion protection of concrete reinforcement in close relation to other commercially used coating technologies—i.e., epoxy coatings and bath hot-dip galvanizing coatings. The application technology of the steel surface is described in detail, and the corrosion performance and bond strength in concrete are compared. The paper also points out the possibility of improving the durability of epoxy coatings by the addition of silanes and, in the case of application to the surface of hot-dip galvanized steel, they can prevent corrosion of the coating by hydrogen evolution. The application potential of organofunctional silanes is also presented in the form of hydrophobic coatings on concrete surfaces or as corrosion inhibitors in simulated concrete pore solutions. The use of a suitable type of modified silane coating on the surface of carbon steel reinforcement can increase the corrosion performance and can also increase the bond strength in concrete. However, these facts need to be experimentally verified. Full article

(This article belongs to the Special Issue Research on Durability and Aging on Materials and Structures in Buildings)

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