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Article

Experimental Study on the Performance of Sustainable Epoxy Resin-Modified Concrete Under Coupled Salt Corrosion and Freeze–Thaw Cycles

by
Zhen Zhang
1,
Fang Zhang
2,
Chuangzhou Wu
3,* and
Yafei Chen
1
1
School of Mechanical and Electrical Engineering, Xinjiang Institute of Technology, Aksu 843100, China
2
School of Energy and Chemical Engineering, Xinjiang Institute of Technology, Aksu 843100, China
3
Ocean College, Zhejiang University, Zhoushan 316021, China
*
Author to whom correspondence should be addressed.
Sustainability 2025, 17(13), 6186; https://doi.org/10.3390/su17136186
Submission received: 22 May 2025 / Revised: 26 June 2025 / Accepted: 3 July 2025 / Published: 5 July 2025
(This article belongs to the Special Issue Sustainable Construction and Built Environments)
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Abstract

Epoxy resin-modified concrete (ERMC) demonstrates significant potential for enhancing the durability of concrete structures exposed to harsh environmental conditions. However, the performance of ERMC under the combined effects of salt erosion and freeze–thaw cycles remains inadequately explored. This study systematically evaluates the durability of ERMC through experimental investigations on specimens with epoxy resin-poly ash ratios of 0%, 5%, 10%, 15%, 20%, and 25%. Resistance to salt erosion was assessed using composite salt solutions with concentrations of 0%, 1.99%, 9.95%, and 19.90%, while frost resistance was tested under combined conditions using a 1.99% Na2SO4 solution. Key performance metrics were analyzed with microstructural observations to elucidate the underlying damage mechanisms, including the compressive strength corrosion coefficient, dynamic elastic modulus, mass loss rate, and flexural strength loss rate. The results reveal that incorporating epoxy resin enhances concrete’s resistance to salt erosion and freeze–thaw damage by inhibiting crack propagation and reducing pore development. Optimal performance was achieved with an epoxy resin content of 10–15%, which exhibited minimal surface deterioration, a denser microstructure, and superior long-term durability. These findings provide critical insights for optimizing the design of ERMC to improve the resilience of concrete structures in aggressive environments, demonstrating that ERM is a sustainable material, and offering practical implications for infrastructure exposed to extreme climatic and chemical conditions.

1. Introduction

The southern Xinjiang region, located along China’s border, plays a pivotal role in national stability, economic development, and ethnic unity, with infrastructure development as a cornerstone for its overall progress. However, the widespread presence of saline soil in this region presents significant durability challenges for concrete structures, severely impacting their long-term performance and structural integrity. For instance, chloride ions in saline soil can penetrate the concrete cover, leading to the corrosion of steel reinforcement. This process causes cracking and spalling of the protective layer (Figure 1a), drastically reducing the structure’s load-bearing capacity [1,2,3,4,5]. Furthermore, sulfate ions react with cement hydration products, forming expansive compounds that generate internal stress within the concrete. These stresses result in cracking and loosening (Figure 1b), ultimately compromising structural integrity [6,7,8,9,10].
In addition to these chemical attacks, the unique climatic conditions of southern Xinjiang—characterized by high temperatures, arid environments, and significant diurnal temperature fluctuations—exacerbate the corrosive effects of saline soil. The combined impact of salt erosion and freeze–thaw cycles accelerates the degradation of concrete structures. Therefore, addressing these durability challenges is essential for supporting regional economic development and maintaining social stability in southern Xinjiang.
Epoxy resin has emerged as an ideal material for enhancing concrete durability in the saline environment, owing to its strong adhesion, outstanding chemical stability, and superior corrosion resistance [11,12,13,14]. Incorporating epoxy resin into concrete modification is expected to significantly improve resistance to saline soil erosion and prolong the service life of infrastructure.
In recent years, extensive research has focused on the mechanical properties of epoxy resin-modified concrete (ERMC). Studies have demonstrated that epoxy resin significantly refines the concrete microstructure and enhances the bond between the cement matrix and aggregates [15,16,17,18]. Powder-filler-modified epoxy resin can be applied as a protective or surface layer on concrete and mortar, improving adhesion and durability [19]. When incorporated into ordinary Portland cement, epoxy resin enhances the flexural toughness of mortar and optimizes its microstructure [20]. The continuous and stable network structure formed by epoxy resin within the concrete effectively distributes and withstands external loads, thereby improving the overall mechanical performance of concrete [21,22,23]. Additionally, the use of waterborne epoxy resin enhanced the mechanical properties of pervious recycled concrete by first improving the pore structure at the microscopic level [24]. Nano-modification of epoxy resin can significantly improve the mechanical properties of concrete [25]. ERMC is resistant to chloride ion penetration and sulfate erosion [26,27]. Epoxy resin effectively fills concrete pores, significantly reducing the diffusion rate of chloride ions [28]. In simulated saline environment tests [29,30], ERMC showed a considerably lower chloride penetration depth than ordinary concrete. The optimized microstructure of ERMC reduces porosity and promotes a more uniform pore distribution [31].
Studies have also focused on latest research on improving the durability of concrete under the effects of salt erosion and freeze–thaw cycles. The quality and durability of the concrete was reduced under the coupling action of freeze–thaw cycle and chloride salt erosion [32]. The relationship between workability, absorption behavior, and scaling resistance with steel fiber content increases of ultra-high-performance concrete was assessed [33]. The addition of polypropylene short fibers (PPFA) enhanced the frost resistance of concrete [34]. The salt-freeze–thaw damage of concrete decreased with the increase of steel fiber dosage [35]. The steel–polypropylene hybrid fiber reinforced concrete had the excellent salt frost resistance during salt–freezing cycles [36].
While previous studies have highlighted the improvement in mechanical properties and durability of ERMC, limited research exists on its performance under the combined effects of salt erosion and freeze–thaw cycles, especially in the saline environment of southern Xinjiang. This gap emphasizes the lack of a solid theoretical foundation for assessing concrete durability under such conditions. Due to the special geographical environment, the saline soil in southern Xinjiang has the characteristics of high salt, easy change, and many hazards. Based on the saline environment conditions in southern Xinjiang, the ion concentrations in the saline soil were determined, and the composite salt solution was prepared according to the ion concentrations, so as to prepare for the follow-up experiments. Through composite salt solution immersion test and a salt erosion–freeze–thaw coupling test, this study investigates the damage and deterioration process of ERMC under sulfate attack and freeze–thaw cycles and evaluates the erosion resistance of modified concrete. Key performance indicators were selected for analysis and assessment, and the microstructural evolution of the specimens during the salt erosion and freeze–thaw process was examined to investigate the influence of epoxy resin on concrete properties under these conditions.

2. Specimen Fabrication

2.1. Experimental Materials

The Conch brand P.O 42.5 ordinary silicate cement was used as the binding material. The fine and coarse aggregates were sourced from a sand and gravel processing plant in Aksu City; the fine aggregate was river sand with a grain size of 2–5 mm, and the coarse aggregate was granite gravel with a grain size of 5–20 mm. The LJ-618 organosilicon defoamer produced by Beijing Gerueilangjie Technology Co., Ltd., Beijing, China was used. The DY-128-50 water-based epoxy resin emulsion and DY-175 water-soluble modified epoxy curing agent produced by Shenyang Dongyan Paint Decoration Co., Ltd., Shenyang, China were used, and the relevant technical indicators are listed in Table 1 and Table 2. Water used was laboratory tap water.

2.2. Mix Proportion of Specimens

The concrete specimens were designed with a strength grade of C30, incorporating six mix proportions with resin-poly ash ratios of 0%, 5%, 10%, 15%, 20%, and 25%. The mix proportions were determined following the Code of JGJ55-2011 [37], as shown in Table 3, and all materials were weighed proportionally. We slowly added the curing agent to the epoxy resin, stirred while adding it, and continued to stir for 2~3 min until a mixture with uniform color was formed. The selected concrete mixer model is HJW-30L produced by Beijing Aerospace Huayu Test Instrument Co., LTD.The modified concrete was prepared by post-mixing, and the cement and aggregate were first put into the mixer and dry mixed for 30 s; then, we added the mixing water and stirred for 1.5 min, forming a preliminary concrete mixture. We slowly poured the epoxy resin mixture into the mixer and continued to stir for 3 min, so that the epoxy resin fully wrapped the aggregate and cement particles. The mixed concrete was poured into a mold with a size of 100 mm × 100 mm × 100 mm, 100 mm × 100 mm × 400 mm, vibrated, and compacted, and then put into a standard curing room (temperature of 20 ± 2 °C, humidity ≥ 95%) for curing. The production process of the concrete specimens is illustrated in Figure 2. According to GB/T 50082-2009 [38], the composite salt solution immersion test was conducted on 100 mm × 100 mm × 100 mm specimens, while the salt erosion and freeze–thaw coupling test used 100 mm × 100 mm × 400 mm specimens. One set of specimens was prepared for each test condition, with three specimens per group.

3. Test Plan

3.1. Composite Salt Solution Immersion Test

3.1.1. Selection of Evaluation Indicators

The code GB/T 50082 [38] defines the compressive strength corrosion coefficient as a standard metric for evaluating concrete degradation under sulfate attack. To comprehensively assess concrete performance under sulfate erosion, this study employs three evaluation indicators, the compressive strength corrosion coefficient, the relative mass, and the relative dynamic elastic modulus, to comprehensively assess concrete performance under sulfate erosion. The calculation formulas for these indicators are provided below.
Kf = (fcn/fc0) × 100
ω1 = (Mr − 0.95)/0.05
ω2 = (Er − 0.6)/0.4
where Kf is the compressive strength corrosion coefficient, accurate to 0.1%; fcn is the average compressive strength of the specimens after salt erosion, accurate to 0.1 MPa; fc0 is the average strength of the control specimens subjected to standard curing at the same age, accurate to 0.1 MPa; ω1 is the relative mass evaluation parameter, accurate to 0.001; Mr is the relative mass, accurate to 0.001; ω2 is the relative dynamic elastic modulus evaluation parameter, accurate to 0.001; and Er is the relative dynamic elastic modulus, accurate to 0.001.

3.1.2. Experimental Design

The ion concentrations of SO42−, Mg2+, Cl−, CO32−, and HCO3− in the top 0–5 cm layer of saline soil from Daoxiang Road, Wensu County, Aksu, Southern Xinjiang, were determined using the titration method. The measured ion concentrations are presented in Table 4.
Based on the content of each ion, a composite salt solution with a baseline salt solute content of 1.99% was prepared by 10% standard solutions such as NaCl, Na2CO3, NaHCO3, MgSO4, and Na2SO4, which was designated as F1. To compare experimental data and validate the test results, additional solutions were prepared: deionized water (F0), a solution with five times the reference concentration (F5), and a solution with 10 times the reference concentration (F10). The concentrations of the composite salt solutions are summarized in Table 5.
Concrete specimens were immersed in the prepared solutions to simulate the in-service conditions of concrete structures in the region. The immersion process is illustrated in Figure 3. At 0, 30, 60, 90, and 120 days of erosion, the compressive strength, mass, and dynamic elastic modulus of the specimens were measured. These data were subsequently used to calculate the compressive strength corrosion coefficient, relative mass evaluation parameter, and relative dynamic elastic modulus evaluation parameter.

3.2. Salt Erosion and Freeze–Thaw Coupling Test

3.2.1. Selection of Evaluation Indicators

According to GB/T 50082-2009 [38], the evaluation criteria for concrete frost resistance include the strength loss rate, mass loss rate, and dynamic elastic modulus loss rate. In this study, three indicators were selected for evaluation: the mass loss rate (ΔM), dynamic elastic modulus loss rate (ΔE), and flexural strength loss rate (Δf). The calculation formulas for these indicators are as follows:
ΔM = (Mc − Md)/Mc × 100
ΔE = (Ec − Ed)/Ec × 100
Δf = (fc − fd)/fc × 100
where ΔM is the mass loss rate, accurate to 0.001%; Mc is the average mass of the control specimens cured under standard conditions at the same age, accurate to 0.001 kg; Md is the average mass of the specimens after n cycles of salt erosion and freeze–thaw coupling, accurate to 0.001 kg; ΔE is the dynamic elastic modulus loss rate, accurate to 0.01%; Ec is the average dynamic elastic modulus of the control specimens, accurate to 0.01 GPa; Edis the average dynamic elastic modulus of the specimens after n cycles of salt erosion and freeze–thaw coupling, accurate to 0.01 GPa; Δf is the flexural strength loss rate, accurate to 0.01%; fc is the average flexural strength of the control specimens, accurate to 0.01 MPa; fd is the average flexural strength of the specimens after n cycles of salt erosion and freeze–thaw coupling, accurate to 0.01 MPa.

3.2.2. Experimental Method

According to GB/T 50082-2009 [38], freeze–thaw cycle tests were performed on 100 mm × 100 mm × 400 mm concrete specimens. After 24 days of standard curing, the specimens were immersed in water at a temperature of 20 ± 2 °C, with the water level maintained 25 mm above the top surface for 4 days. Upon completion of immersion, the specimens were removed, surface water was wiped off, and initial measurements of the mass, dynamic elastic modulus, and flexural strength were recorded. Subsequently, the specimens were placed in containers filled with a 1.99% Na2SO4 solution, ensuring that the solution level kept 10 mm above the top surface. The salt erosion and freeze–thaw coupling test was then initiated. The freeze-thaw cycle test machine model is TDRF-Ⅱ produced by Changsha Yaxing CNC Technology Co., LTD. Freeze–thaw cycling was performed in a test chamber, the internal structure shown in Figure 4. The freeze–thaw temperature in the center of the specimen was controlled at −18 ± 2 °C and 5 ± 2 °C, respectively, each freeze–thaw cycle was completed within 2–4 h, the temperature difference between the inside and outside of the specimen was ≤28 °C, and the transition time between freezing and thawing was ≤10 min. At 25, 50, 75, and 100 freeze–thaw cycles, the mass, dynamic elastic modulus, and flexural strength of the specimens were measured. Before each measurement, the specimens were cleaned to remove surface residue, wiped dry, and inspected for visible external damage. Additionally, microscopic morphological analysis was performed to investigate erosion and degradation mechanisms under freeze–thaw conditions. The collected data were used to comprehensively evaluate the concrete specimens’ frost resistance and deterioration behavior.

4. Experimental Results and Analysis

4.1. Analysis of Surface Damage

To assess the extent of surface damage in concrete specimens subjected to salt erosion, the appearance of the specimens was documented throughout the erosion process. A comparative analysis of the same area surface morphology of the P0, P10, and P25 specimens after 90 days of exposure was conducted. The horizontal and vertical dimensions of the selected comparison surfaces were 25–75 cm, as shown in Figure 5. The proportion of the surface holes of specimens was calculated by Image J (1.54g), as shown in Figure 6. After 90 days of erosion in the F1 solution, all specimens exhibited varying degrees of surface damage, including material detachment and hole formation. Among them, the P0 specimen sustained the most severe deterioration, with an extensive loss of surface cementitious materials, resulting in large, interconnected holes that further compromised surface integrity; the proportion of surface holes reached 14.276%. The P25 specimen exhibited moderate damage, characterized by partial detachment of cementitious materials and the presence of numerous holes; the proportion of surface holes reached 13.593%. In contrast, the P10 specimen exhibited the least damage, with only minor detachment of surface cementitious materials and the formation of small and sparse holes; the proportion of surface holes was only 7.069%, which was 50.48% lower than that of P0 and 48% lower than that of P25. These findings indicate that incorporating epoxy resin in concrete effectively mitigates surface damage caused by salt erosion.
The surface appearance of specimens was continuously monitored throughout the freeze–thaw cycle tests to evaluate surface deterioration under salt erosion and freeze–thaw coupling effects. After 100 freeze–thaw cycles, the same area surface characteristics of P0, P10, and P25 specimens were analyzed for comparison. The horizontal dimensions of the selected comparison surfaces was 150 cm–250 cm, and the vertical size was 25 cm–75 cm, as shown in Figure 7. The proportion of the surface holes of specimens was calculated by Image J, as shown in Figure 8. All specimens exhibited a significant increase in surface damage after 100 freeze–thaw cycles. The P0 specimen experienced the most severe deterioration, with the partial exposure of fine aggregates and the appearance of a crack, and the proportion of surface holes reached 17.981%. The P25 specimen exhibited moderate deterioration, displaying holes connected and fine aggregates exposed, the proportion of surface holes reached 17.884%. In contrast, the P10 specimen showed the least damage, with fewer traces of cementitious material detachment and minimal surface degradation; the proportion of surface holes was only 13.894%, which was 22.73% lower than that of P0 and 22.31% lower than that of P25. These results indicate that incorporating an appropriate amount of epoxy resin effect mitigates surface damage under salt erosion and freeze–thaw coupling conditions.

4.2. Variation of Compressive Strength Corrosion Coefficients

The variation curves of compressive strength corrosion coefficients for specimens with different epoxy resin contents under salt erosion are shown in Figure 9. As erosion age increased, the Kf values of the P0–P25 specimens immersed in the F0–F10 solutions gradually declined. Under the same salt erosion conditions, the Kf values initially increased and then decreased with the addition of epoxy resin. In the F0 solution, the P15 specimen exhibited the lowest reduction rate in Kf, showing a 3.14% improvement compared to the P0 specimen after 120 days of erosion. After 90 days of erosion in F1 solution, the standard deviation of Kf for P0 was 1.25, and that for P10 was 0.79, which was 36.8% lower than that of P0 samples. In the F1–F10 solutions, the P10 specimen demonstrates the slowest reduction in Kf, with improvements of 5.04%, 5.39%, and 7.38% compared to the P0 specimen after 120 days. In the F5 solution, the Kf value of P10 was 86.1% after 120 days of erosion, better than previous studies, at 84.05% [39]. These results indicate that epoxy resin effectively enhances the erosion resistance of concrete. When the epoxy resin content was 10–15%, the fluctuations in Kf were minimal, the reduction rate was low, the standard deviation was relatively small, the structure was stable, and the performance was relatively superior.
The enhancement in Kf values with an optimal epoxy resin content is primarily attributed to its ability to enhance the concrete microstructure. The epoxy resin fills internal pores, increasing compactness, while its hydroxyl and ether functional groups chemically bond with cementitious materials during hydration [19]. This reaction forms a dense three-dimensional network, strengthening the bonding between hydrated products and significantly improving the resistance of concrete resistance to salt erosion.
However, excessive epoxy resin reduces the availability of internal water, thereby hindering hydration [40,41]. The surplus resin can encapsulate aggregates, impeding cement hydration and forming polymer films with low strength and elasticity within the concrete. These films are susceptible to damage under salt erosion or external forces, ultimately reducing Kf values and compromising durability.

4.3. Variation of Relative Mass

The variation curves of the relative mass evaluation parameter for specimens with different epoxy resin contents under salt erosion are presented in Figure 10.
The relative mass evaluation parameter (ω1) of all specimens (P0–P25) initially increased and then decreased as erosion age progressed under immersion in F0–F10 solutions. As the concentration of the composite salt solution and erosion age increased, P0 specimens exhibited the most significant fluctuations in ω1 values. With increasing epoxy resin content, the variation in ω1 initially decreased and then increased. Among the tested specimens, P5, P20, and P25 displayed more pronounced fluctuations, whereas P10 and P15 exhibited relatively stable ω1 values, as shown in Figure 10. These findings indicate that incorporating epoxy resin enhances the structural stability of concrete. When the epoxy resin content ranges of 10–15%, ω1 fluctuations are minimal, and variation rates slow down, contributing to superior performance.
The observed trend is primarily attributed to the presence of pores in concrete specimens. During the early stages of immersion in the composite salt solution, water penetrated the specimens and fills internal pores, leading to a rise in ω1 values. As immersion continued, the pores became saturated, and prolonged exposure resulted in surface and internal damage, causing the detachment of cementitious materials. Over time, the mass loss increased, leading to a gradual decline in ω1 values. The addition of epoxy resin reduced internal porosity, enhanced concrete compactness [20,42,43], and limited the increase in ω1 values, thereby improving the overall durability of the concrete.

4.4. Variation of Relative Dynamic Elastic Modulus

The variation curves of the relative dynamic elastic modulus evaluation parameters for specimens with different epoxy resin contents under salt erosion are shown in Figure 11.
The relative dynamic elastic modulus evaluation parameter (ω2) of P0–P25 specimens immersed in F0–F10 solutions initially increased and then decreased as erosion age progressed. As the concentration of the composite salt solution and erosion age increased, the ω2 values of P0 specimens exhibited the most significant fluctuations. With increasing epoxy resin content, the fluctuation amplitude of ω2 initially decreased and then increased. Among the specimens, P5, P20, and P25 demonstrated reduced fluctuation amplitudes compared to P0, while P10 and P15 exhibited the least variation, maintaining a relatively stable ω2 value around 1.300, as illustrated in Figure 11.
These findings confirm that incorporating epoxy resin into concrete significantly enhances its structural stability. When the epoxy resin content was 10–15%, the fluctuation amplitude and variation rate of ω2 were minimal, indicating enhanced structural integrity and superior durability.
The observed trends can be attributed to the interaction between the salt solution and concrete during erosion. In the initial stage, the salt solution infiltrated the specimen, filling internal pores and increasing the dynamic elastic modulus, leading to a rise in ω2 values. However, as erosion progressed, surface and internal damage intensified, causing a gradual reduction in dynamic elastic modulus and a corresponding decline in ω2 values.
Incorporating an optimal amount of epoxy resin enhances concrete performance through multiple mechanisms. First, it accelerates hydration reactions [44,45], reducing the presence of free water. Second, it fills capillary pores, minimizing internal voids, which refines the microstructure and increases compactness. These effects collectively limit the increase in ω2 values, improving concrete stability and long-term durability.

4.5. Mass Loss Analysis

The variation in mass and mass loss rate for specimens with different epoxy resin contents under salt erosion and freeze–thaw coupling conditions is illustrated in Figure 12.
The mass of all specimens (P0–P25) gradually decreased as the number of freeze–thaw cycles increased. After 100 cycles, the mass loss rates (ΔW) for the P0–P25 specimens were 2.57%, 1.69%, 0.95%, 1.19%, 1.58%, and 1.78%, respectively. Among them, the P0 specimen exhibited the most pronounced mass loss, while the P5, P20, and P25 specimens showed relatively lower mass loss rates compared to P0. Notably, the P10 and P15 specimens experienced the least variation in ΔW, demonstrating superior resistance to freeze–thaw damage, as illustrated in Figure 12.
These findings indicate that as epoxy resin content increases, the variation amplitude of ΔW initially decreases and then increases. Incorporating epoxy resin enhances concrete’s resistance to salt erosion and freeze–thaw cycles. When the epoxy resin content ranged from 10% to 15%, ΔW fluctuations were minimal, and the mass loss rate remained low, demonstrating superior durability.
The observed mass loss primarily resulted from surface deterioration and microcrack formation caused by salt erosion and freeze–thaw cycles. These degradation mechanisms led to the separation of slurry particles, fine aggregates, and the cementitious matrix, resulting in surface spalling and material detachment, which ultimately contributed to mass loss. With prolonged exposure to salt erosion and freeze–thaw cycles, the extent of spalling and detachment increased, causing gradual mass loss and a corresponding upward trend in ΔW values.
Incorporating an appropriate amount of epoxy resin into concrete effectively mitigates surface deterioration and mass loss by filling internal pores and forming a dense three-dimensional network with cementitious materials [11]. This enhances internal compactness, thereby limiting the increase in ΔW values and significantly improving frost resistance. However, excessive epoxy resin may encapsulate aggregates, impede hydration, and reduce overall compactness. Additionally, surplus epoxy resin can aggregate to form polymer films with low mechanical properties, such as reduced strength and elastic modulus. These films are susceptible to damage under salt erosion and freeze–thaw cycles, leading to an increase in ΔW values and a decline in frost resistance.

4.6. Analysis of Dynamic Elastic Modulus Loss

The variation curves of dynamic elastic modulus and dynamic elastic modulus loss rate for specimens with different epoxy resin contents under salt erosion and freeze–thaw coupling conditions are presented in Figure 13.
With an increasing number of freeze–thaw cycles, the dynamic elastic modulus of all specimens (P0–P25) gradually decreased, as illustrated in Figure 13. After 100 freeze–thaw cycles, the dynamic elastic modulus loss rates (ΔE) for P0–P25 specimens were 13.74%, 11.44%, 9.58%, 8.92%, 11.78%, and 12.36%, respectively. Among them, the P0 specimen exhibited the most significant ΔE variation and the fastest decline. In contrast, the P5, P20, and P25 specimens showed relatively lower ΔE variations, while P10 and P15 specimens demonstrated the smallest fluctuations, indicating enhanced durability.
These findings suggest that as the epoxy resin content increases, ΔE values initially decrease and then increase. The incorporation of epoxy resin effectively slowed the decline in dynamic elastic modules, improving concrete’s resistance to salt erosion and freeze–thaw cycles. Specimens with 10–15% epoxy resin content exhibited minimal ΔE fluctuations and a slower reduction in dynamic elastic modulus, demonstrating superior performance.
The observed trends can be attributed to the synergistic effects of sulfate erosion and freeze–thaw cycles. Sulfate ions progressively corrode the specimen surface, while repeated freeze–thaw cycles cause water molecules within the concrete to freeze and expand, generating internal stress [46,47]. Over time, this frost-induced stress intensifies, leading to progressive surface and internal damage, which accelerates the decline in dynamic elastic modulus. As the duration of salt erosion and freeze–thaw coupling increases, the severity of frost heave intensifies, resulting in greater dynamic elastic modulus loss and a continuous rise in ΔE values.
Incorporating epoxy resin mitigates these effects by enhancing the hydration process, which reduces the amount of free water available for freezing and subsequently minimizes the impact of frost heave. Additionally, epoxy resin effectively fills internal pores, reducing overall porosity and promoting a more uniform and compact microstructure. This structural refinement not only limits the formation and propagation of cracks but also enhances the overall bonding between hydration products, further improving concrete’s resistance to sulfate attack and freeze–thaw damage. As a result, the increase in ΔE values is significantly reduced, leading to improved durability and long-term stability of ERMC under harsh environmental conditions.

4.7. Analysis of Flexural Strength Loss

The variation curves of flexural strength and flexural strength loss rate for specimens with different epoxy resin contents under salt erosion and freeze–thaw coupling conditions are illustrated in Figure 14.
With an increasing number of freeze–thaw cycles, the flexural strength of all specimens (P0–P25) exhibited a gradual decline, as shown in Figure 14. Under the same freeze–thaw conditions, the flexural strength loss rate (Δf) initially decreased and then increased with rising epoxy resin content. After 100 freeze–thaw cycles, the Δf values for P0–P25 specimens were 19.73%, 15.61%, 12.60%, 13.73%, 16.16%, and 17.31%, respectively. Among these, the P0 specimen experienced the largest variation in Δf and the fastest decline. In contrast, the P5, P20, and P25 specimens showed moderate fluctuations in Δf, while the P10 and P15 specimens exhibited the smallest variations, indicating improved resistance to freeze–thaw damage.
These findings confirm that the incorporation of epoxy resin significantly enhances concrete’s flexural strength. When the epoxy resin content was within the 10–15% range, Δf fluctuations remained minimal, and the rate of flexural strength loss decreasds, demonstrating superior durability and structural stability.
The decline in flexural strength is primarily attributed to surface and internal degradation induced by salt erosion and freeze–thaw cycles. This degradation intensifies frost heave stress, caused by internal water expansion, progressively weakening the concrete matrix and leading to a gradual reduction in flexural strength.
By incorporating an optimal amount of epoxy resin, a dense three-dimensional network structure was formed within the concrete matrix, enhancing its compactness. This structural refinement effectively improved flexural performance and mitigates strength loss, thus enhancing the long-term durability of the concrete.

4.8. Relationship Between Flexural Strength and Dynamic Elastic Modulus

As illustrated in Figure 15, the correlation between flexural strength and dynamic elastic modulus exhibited notable variations among specimens with different epoxy resin contents subjected to salt erosion and freeze–thaw coupling conditions.
The flexural strength of the specimens declined in parallel with the reduction in dynamic elastic modulus, with the rate of flexural strength loss slightly exceeding that of dynamic elastic modulus, as illustrated in Figure 15. A significant correlation was observed between these two parameters. For instance, in the case of P10, after 100 freeze–thaw cycles, the dynamic elastic modulus decreased by 9.58%, while the flexural strength loss reached 12.60%.
The difference in reduction rates between dynamic elastic modulus and flexural strength is primarily attributed to their distinct damage mechanisms. Dynamic elastic modulus is predominantly influenced by surface deterioration, whereas flexural strength is more sensitive to internal structural degradation. During salt erosion and freeze–thaw coupling, internal frost heave stress exerts a more substantial impact on the specimens than surface damage. The freezing and expansion of internal pore water induces stress concentrations within the concrete matrix, leading to progressive microcrack development and loss of internal cohesion. This process compromises the structural integrity of the specimens, ultimately resulting in a slightly higher reduction rate in flexural strength compared to dynamic elastic modulus.

5. SEM Analysis

To further investigate the degradation mechanisms of concrete specimens with different epoxy resin contents under salt erosion and salt erosion-freeze–thaw coupling, Scanning Electron Microscopy (SEM) was employed to examine their microstructural morphology. SEM images of P0, P10, and P25 specimens were selected for comparative analysis between 30 and 120 days of erosion. The corresponding SEM images are shown in Figure 16.
At an erosion age of 30 days, the P0 specimen exhibited elongated cracks and a relatively loose microstructure, suggesting significant material degradation, as shown in Figure 16. In contrast, the P25 specimen showed no visible elongated cracks but contained numerous noticeable pores, indicating the presence of internal voids despite the absence of major cracking. The P10 specimen demonstrated the most compact microstructure, free of visible cracks, with smaller and fewer pores, reflecting enhanced structural integrity.
After 120 days of immersion in the salt solution, the P0 specimen suffered severe erosion, with a substantial increase in pore formation and enlarged microstructural cracks, accelerating the degradation process. While the P10 and P25 specimens also exhibited an increase in pore quantity and the development of larger pores compared to their pre-erosion state, the rate of pore formation and overall erosion severity remained significantly lower than those observed in the P0 specimen. Among them, the P10 specimen retained a relatively compact structure, with smaller and less interconnected pores, demonstrating superior resistance to salt erosion.
The SEM images of P5, P10, and P25 specimens after 25 and 100 freeze–thaw cycles were selected for comparative analysis to examine the microstructural degradation characteristics of ERMC. These images provide valuable insights into the effects of freeze–thaw cycling on concrete durability. The corresponding SEM images are presented in Figure 17.
After 25 freeze–thaw cycles, the P0 specimen exhibited elongated cracks and numerous pores, indicating significant microstructural deterioration. The P25 specimen, while free of elongated cracks, exhibited a high pore density and a relatively loose microstructure. In contrast, the P10 specimen showed no visible cracks, had fewer and smaller pores, and maintained a more compact microstructure, suggesting improved resistance to freeze–thaw damage.
After 100 freeze–thaw cycles, all specimens exhibited progressive deterioration and visible signs of erosion. The P0 specimen suffered the most severe damage, characterized by deeper and wider cracks and a higher number of pores. The P10 and P25 specimens also showed an increase in pore size and quantity compared to their pre-erosion state, with the P25 specimen even displaying indications of large crack formation. However, the extent of damage in the P10 and P25 specimens was significantly lower than that in the P0 specimen. Notably, the P10 specimen retained a relatively compact structure, with fewer and smaller pores, indicating enhanced resistance to freeze–thaw damage.
These findings suggest that concrete containing 10–15% epoxy resin demonstrates enhanced resistance to freeze–thaw erosion, maintaining superior durability and structural integrity.
The improvement in durability is attributed to the role of epoxy resin in promoting hydration and refining the microstructure. In the absence of epoxy resin, incomplete hydration leaves cracks and unfilled pores, reducing erosion resistance. The incorporation of an optimal epoxy resin content accelerates hydration, facilitating the formation of a dense three-dimensional network, which minimizes pore and crack formation, thereby enhancing compactness and durability [48]. However, excessive epoxy resin inhibits hydration, forms weak polymer films, and increases porosity, ultimately diminishing erosion resistance.

6. Conclusions

This study provides a comprehensive assessment of the degradation mechanisms and performance optimization of ERMC under the combined effects of salt erosion and freeze–thaw cycles, simulating real saline soil environments. Through composite salt solution immersion tests and salt erosion-freeze–thaw coupling tests, the durability of ERMC with varying epoxy resin contents (0–25%) was systematically evaluated. The analysis incorporated key durability indicators, including the compressive strength corrosion coefficient, mass loss rate, dynamic elastic modulus, and microstructural evolution, to elucidate material behavior and degradation patterns. The primary conclusions are as follows:
(1)
After 90 days of erosion in F1 solution, the surface porosity of P10 was 7.069%, which was 50.48% lower than that of P0 and 48% lower than that of P25. The standard deviation of Kf for P10 was 0.79, which was 36.8% lower than that of P0, and the average value of Kf for P10 increased 5.04% compared to P0. Under identical salt erosion conditions, both ω1 and ω2 of P0-P25 specimens initially increased before gradually decreasing with prolonged exposure. As the epoxy resin content increased, their fluctuation amplitudes first decreased and then rose.
(2)
After 100 freeze–thaw cycles, the surface porosity of P10 was 13.894%, which was 22.73% lower than that of P0 and 22.31% lower than that of P25. The ΔW of P0 was 2.57%, whereas that of P15 was 0.95%, marking a 63.04% reduction. The ΔE of P0 was 13.74%, whereas that of P15 was 8.92%, marking a 35.08% reduction. The Δf of P0 was 19.73%, whereas that of P15 was 13.73%, marking a 30.41% reduction. Under the same number of freeze–thaw cycles, the loss rates of dynamic elastic modulus and flexural strength exhibited an initial decline followed by an increase as epoxy resin content increased.
(3)
After 120 days of immersion in the salt solution, the P0 suffered severe erosion, with a substantial increase in pore formation and enlarged microstructural cracks, but the P10 retained a relatively compact structure, with smaller and less interconnected pores, demonstrating superior resistance to salt erosion. After 100 freeze–thaw cycles, the P0 exhibited extensive cracking and increased porosity, whereas P10 and P15 remained crack-free with fewer and smaller pores, maintaining a denser internal structure. An appropriate amount of epoxy resin effectively suppresses crack and pore development under salt erosion and freeze–thaw coupling.
(4)
According to the statistical analysis of the data, incorporating an optimal amount of epoxy resin significantly enhances concrete resistance to salt erosion and freeze–thaw cycles. Concrete with 10–15% epoxy resin exhibited minimal surface deterioration, slower degradation in mechanical properties, and a denser microstructure. It showed the lowest reduction rates in the compressive strength corrosion coefficient, relative mass, relative dynamic elastic modulus, and strength loss parameters, demonstrating superior resistance to salt erosion and freeze–thaw damage, making it a sustainable material.

Author Contributions

Conceptualization, Z.Z. and C.W.; methodology, Z.Z., F.Z. and C.W.; software, Z.Z., F.Z. and Y.C.; validation, Z.Z., C.W. and Y.C.; formal analysis, Z.Z. and F.Z.; investigation, Z.Z.; data curation, Z.Z. and F.Z.; writing—original draft preparation, Z.Z., F.Z. and C.W.; writing—review and editing, Z.Z., C.W., F.Z. and Y.C.; visualization, Z.Z. and C.W.; supervision, C.W. and Y.C.; funding acquisition, Z.Z. and C.W. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the University Scientific Research Plan Project approved by the Education Department of Xinjiang Uygur Autonomous Region, grant number XJEDU2023P154.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

The data presented in this study are available on request from the corresponding author.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Zhang, M.S.; Chiu, C.F.; Zhou, Y.Z.; Wang, Y.N. Compression and water retention behavior of saline soil improved by MICP combined with activated carbon. Sci. Rep. 2024, 14, 31484. [Google Scholar] [CrossRef]
  2. Xiao, S.X.; Bu, X.; Chen, Y.F.; Wang, X.W. Investigating the damage-based seismic performance of the blind bolt-connected steel framework. Structures 2024, 69, 107388. [Google Scholar] [CrossRef]
  3. Deng, Y.H.; Yan, C.W.; Niu, P.K. Hysteretic model of reinforced concrete bridge piers based on earthquake damage and corrosion from saline soil. Soil Dyn. Earthq. Eng. 2023, 166, 107732. [Google Scholar] [CrossRef]
  4. Tamayo, P.; Rico, J.; López-Gayarre, F.; Fiol, F.; Panzera, T.H.; Thomas, C. Effect of siderurgical aggregates on concrete exposed to saline environments. Constr. Build. Mater. 2022, 352, 129061. [Google Scholar] [CrossRef]
  5. Deng, Y.H.; Yan, C.W.; Li, J.; Liu, S.S.; Zhang, J.; Wang, J.J. Seismic deformation of reinforced concrete piers corroded by saline soil. Bull. Earthq. Eng. 2022, 20, 6763–6788. [Google Scholar] [CrossRef]
  6. Zhang, J.; Lai, Y.M.; Zhang, M.Y.; Li, S.Y.; Li, D.Q.; You, Z.M. Numerical study on the hydro-thermal-chemical–mechanical coupling mechanism in sulfate saline soil under freeze–thaw cycles. Comput. Geotech. 2024, 176, 106803. [Google Scholar] [CrossRef]
  7. Ji, F.L.; Peng, Y.S.; Lv, Q.F.; Li, W.; Yu, J.J. Pure salt expansion behavior in sulfate saline soil under negative temperature conditions. Cold Reg. Sci. Tech. 2024, 225, 104273. [Google Scholar] [CrossRef]
  8. Li, H.B.; Kang, X.R.; Li, S.; Shan, L.; Zhang, Z.; Wang, Z. Characterization and mechanism study of sulfate saline soil solidification in seasonal frozen regions using ternary solid waste-cement synergy. Constr. Build. Mater. 2024, 427, 136263. [Google Scholar] [CrossRef]
  9. Wang, F.J.; Jiang, J.Y.; Zhang, A.N.; Wang, L.G.; Sui, S.Y. Sulfate transport assessment of cementitious materials-solidified saline soil. J. Sustain. Cen.-Based Mater. 2023, 12, 1577–1591. [Google Scholar]
  10. Yang, B.; Hu, X.P.; Zhong, S.; Sun, J.J.; Peng, G. Macroscopic properties evolution and microstructural analysis of early-age concrete in sulfate saline soil. Constr. Build. Mater. 2024, 431, 136607. [Google Scholar] [CrossRef]
  11. Wang, C.J.; Wang, Z.H.; Liu, S.P.; Luo, H.X.; Fan, W.H.; Liu, Z.J.; Liu, F.T.; Wang, H.Y. Anti-corrosion and wear-resistant coating of waterborne epoxy resin by concrete- like three-dimensional functionalized framework fillers. Chem. Eng. Sci. 2021, 242, 116748. [Google Scholar] [CrossRef]
  12. Fahim, H.G.; Mohd, S.A.R.; Iman, F.; Hajmohammadian, B.M. Performance of Epoxy Resin Polymer as Self-Healing Cementitious Materials Agent in Mortar. Materials 2021, 14, 1255. [Google Scholar] [CrossRef]
  13. Natarajan, S.; Pillai, N.N.; Murugan, S. Experimental Investigations on the Properties of Epoxy-Resin-Bonded Cement Concrete Containing Sea Sand for Use in Unreinforced Concrete Applications. Materials 2019, 12, 645. [Google Scholar] [CrossRef] [PubMed]
  14. Krzywiński, K.; Sadowski, Ł. The Effect of Texturing of the Surface of Concrete Substrate on the Pull-Off Strength of Epoxy Resin Coating. Coatings 2019, 9, 143. [Google Scholar] [CrossRef]
  15. Szewczak, A.; Łagód, G. Experimental Research on the Possibility of Changing the Adhesion of Epoxy Glue to Concrete. Materials 2024, 17, 5398. [Google Scholar] [CrossRef] [PubMed]
  16. Chen, P.Q.; Li, Y.Q.; Zhou, X.J.; Wang, H.; Li, J. Study on the Bond Performance of Epoxy Resin Concrete with Steel Reinforcement. Buildings 2024, 14, 2905. [Google Scholar] [CrossRef]
  17. Kashyzadeh, R.K. Effect of Corrosive Environment on the High-Cycle Fatigue Behavior of Reinforced Concrete by Epoxy Resin: Experimental Study. Polymers 2023, 15, 3939. [Google Scholar] [CrossRef]
  18. Zhang, W.B.; Liu, Z.Y.; Liu, Q.B.; Zhang, W.Q. Investigation of bond behavior between waterborne epoxy-coated steel reinforcing bars (WECR) and concrete. J. Build. Eng. 2023, 76, 107328. [Google Scholar] [CrossRef]
  19. Andrzej, S.; Grzegorz, Ł. Adhesion of Modified Epoxy Resin to a Concrete Surface. Materials 2022, 15, 8961. [Google Scholar] [CrossRef]
  20. Gong, J.Q.; Li, K. Minimizing Drying Shrinkage and Enhancing Impermeability of Foam Concrete Modified with Epoxy Resin. Adv. Civ. Eng. 2020, 2020, 8897687. [Google Scholar] [CrossRef]
  21. Geng, W.Z.; Li, C.G.; Zeng, D.L.; Chen, J.Y.; Wang, H.T.; Liu, Z.Z.; Liu, L.C. Effect of epoxy resin surface-modified techniques on recycled coarse aggregate and recycled aggregate concrete. J. Build. Eng. 2023, 76, 107081. [Google Scholar] [CrossRef]
  22. Zhang, Z.; Zhang, H.L.; Lv, W.J.; Zhang, J.M.; Wang, N. Micro-structure characteristics of unsaturated polyester resin modified concrete under fatigue loads and hygrothermal environment. Constr. Build. Mater. 2021, 296, 123766. [Google Scholar] [CrossRef]
  23. Guo, S.Y.; Zhang, X.; Chen, J.Z.; Mou, B.; Shang, H.S.; Wang, P.; Zhang, L.H.; Ren, J. Mechanical and interface bonding properties of epoxy resin reinforced Portland cement repairing mortar. Constr. Build. Mater. 2020, 264, 120715. [Google Scholar] [CrossRef]
  24. Xia, D.T.; Xia, P.; Hu, J.; Li, X.Y.; Zhan, Z.J. Optimization of mechanical properties of pervious recycled concrete using polypropylene fiber and waterborne epoxy resin. Structures 2024, 63, 106372. [Google Scholar] [CrossRef]
  25. Lei, Z.; Xiao, T.Y.; Yang, C.B.; Li, Z.P.; Shi, X.M. Improving the performance of CFRP-reinforced concrete cylinders in sulfate-laden environment through nanoclay modification of epoxy resin. Constr. Build. Mater. 2024, 436, 136860. [Google Scholar] [CrossRef]
  26. Shen, B.H.; Sheng, Y.P.; Abdulakeem, A.; Zhu, C.Y.; Yang, H.F.; Wang, L.B. An experimental characterization of the properties of graphene oxide—Waterborne epoxy resin coating of concrete after chloride erosion. Constr. Build. Mater. 2024, 428, 136207. [Google Scholar] [CrossRef]
  27. Zhang, H.X.; Sun, X.W.; Wang, Y. Bond performance of NSM FRP–concrete interfaces with epoxy under chloride-salt conditioned environments. Struct. Concr. 2024, 25, 2269–2288. [Google Scholar] [CrossRef]
  28. Luo, D.M.; Li, F.; Niu, D.T. Study on the deterioration of concrete performance in saline soil area under the combined effect of high low temperatures, chloride and sulfate salts. Cem. Concr. Comp. 2024, 150, 105531. [Google Scholar] [CrossRef]
  29. Tian, H.Z.; Qiao, H.X.; Feng, Q.; Han, W.W. Corrosion Deterioration of Reinforced Concrete in a Saline Soil Environment. J. Mater. Civ. Eng. 2023, 35, 04023387. [Google Scholar] [CrossRef]
  30. Fu, Y.; Qiao, H.X.; Hakuzweyezu, T.; Qiao, G.B.; Guo, F. Accelerated Deterioration Mechanism and Reliability Evaluation of Concrete in Saline Soil Area. J. Wuhan Univ. Technol.-Mater. Sci. Ed. 2023, 38, 582–590. [Google Scholar] [CrossRef]
  31. Wang, L.; Zhang, B.; Zhang, H.L.; Zhao, B.D.; Wang, B.; Zhao, Q.M.; Sun, M. Research on Flexural and Freeze–Thaw Properties of Polypropylene-Fiber-Reinforced Pavement Concrete Containing Waterborne Epoxy. Coatings 2023, 13, 1035. [Google Scholar] [CrossRef]
  32. Zhang, J.H.; Li, J.; Yun, H.; Long, J.Z.; Zhu, Q.X.; Guan, Z.G. Durability of new-to-old concrete interface under coupling action of freeze-thaw cycle and chloride salt erosion. Structures 2024, 70, 107867. [Google Scholar] [CrossRef]
  33. Deng, Q.; Wang, Z.X.; Li, S.H.; Yu, Q.L. Salt scaling resistance of pre-cracked ultra-high performance concrete with the coupling of salt freeze-thaw and wet-dry cycles. Cem. Concr. Compos. 2024, 146, 105396. [Google Scholar] [CrossRef]
  34. Ning, X.L.; Liu, Z.Y.; Li, Y.Y.; You, Z.G.; Zhang, Z.K.; Li, J.F. Bond durability between GFRP rebars and fiber reinforced self-compacting concrete under coupled chloride salt and freeze-thaw cycles. Acta Mater. Compos. Sin. 2024, 1–18. [Google Scholar] [CrossRef]
  35. Ding, Y.N.; Ge, M.L.; Liu, Q.W.; Zhu, H. Effect of macro steel fiber on damage of concrete after salt freeze-thaw cycle. J. Civil Environ. Eng. 2024, 46, 159–166. [Google Scholar]
  36. Xia, D.T.; Feng, C.L.; Zheng, Z.; Wu, H. Salt-frost damage model of hybrid fiber reinforced concrete under the coupling action of salt-freeze-thaw cycles. Eng. J. Wuhan Univ. 2024, 57, 55–63. [Google Scholar]
  37. JGJ 55-2011; Specification for Mix Proportion Design of Ordinary Concrete. Ministry of Housing and Urban-Rural Development of the People’s Republic of China: Beijing, China; China Architecture & Building Press: Beijing, China, 2011; pp. 4–14.
  38. GB/T 50082-2009; Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete. Ministry of Housing and Urban-Rural Development of the People’s Republic of China: Beijing, China; China Architecture & Building Press: Beijing, China, 2009; pp. 6–14.
  39. Zhang, X.Y. Research on Anti-corrosion Performance and Mechanism of Concrete in Saline Soil Environment. M.A. Thesis, Taiyuan University of Technology, Taiyuan, China, 2020; p. 42. [Google Scholar]
  40. Li, P.F.; Lu, W.; An, X.H.; Zhou, L.; Du, S.L. Effect of Epoxy Latexes on the Mechanical Behavior and Porosity Property of Cement Mortar with Different Degrees of Hydration and Polymerization. Materials 2024, 14, 517. [Google Scholar] [CrossRef]
  41. Zhang, Z.H.; Li, M.; Liu, G.; Zhou, P.; Qi, H. Effects of waterborne epoxy resin on the mechanical properties and microstructure of slag cementing slurries. J. Disper. Sci. Technol. 2023, 44, 1932–1939. [Google Scholar] [CrossRef]
  42. Wang, Y.X.; Liu, Q.S. Investigation on fundamental properties and chemical characterization of water-soluble epoxy resin modified cement grout. Constr. Build. Mater. 2021, 299, 123877. [Google Scholar] [CrossRef]
  43. Zhong, X. Preparation and mechanical properties of cement concrete modified by waterborne epoxy resin. ‌J. Funct. Mater. 2021, 52, 12008–12012. [Google Scholar]
  44. Liang, X.J. Preparation and durability experimental analysis of epoxy resin modified cement concrete. ‌J. Funct. Mater. 2023, 54, 3217–3223. [Google Scholar]
  45. Li, L.J.; Qin, D.J.; Xu, Z.J.; Feng, Y. Study on Strengthening Mechanism of Epoxy Resin/Rubber Concrete Interface by Molecular Dynamics Simulation. Adv. Civil Eng. 2022, 2022, 5100758. [Google Scholar] [CrossRef]
  46. Li, H.; Guo, H.L.; Zhang, Y. Deterioration of concrete under the coupling action of freeze–thaw cycles and salt solution erosion. Rev. Adv. Mater. Sci. 2022, 61, 322–333. [Google Scholar] [CrossRef]
  47. Li, L.L.; Kang, K.; Feng, Z.P.; Xiao, Q.B.; Xiao, Q.H. Study on performance deterioration of recycled concrete under coupling effect of freeze-thaw and sulfate. J. Xi’an Univ. Arch. Tech. (Nat. Sci. Ed.). 2023, 55, 571–577. [Google Scholar]
  48. Huang, Y.X.; Xiong, C.S.; Yang, H.; Jin, Z.Q.; Wang, P.G.; Guo, X.K.; Wang, Z.R.; Hu, Y.; Zhao, X.Y. Effect of temperature on epoxy resin deterioration for fibre-reinforced polymer reinforcement in simulated concrete pore solutions. Constr. Build. Mater. 2023, 409, 133701. [Google Scholar]
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Figure 1. Structural damage of concrete caused by saline soil. (a) The concrete cover cracks and peels off; (b) concrete pavement expands and cracks.
Figure 1. Structural damage of concrete caused by saline soil. (a) The concrete cover cracks and peels off; (b) concrete pavement expands and cracks.
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Figure 2. The production process of the concrete specimens.
Figure 2. The production process of the concrete specimens.
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Figure 3. The schematic diagram of concrete specimen immersion.
Figure 3. The schematic diagram of concrete specimen immersion.
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Figure 4. The internal structure of the freeze–thaw cycle test box.
Figure 4. The internal structure of the freeze–thaw cycle test box.
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Figure 5. Appearance of specimens with an erosion age of 90 days. (a) P0 specimens; (b) P10 specimens; (c) P25 specimens.
Figure 5. Appearance of specimens with an erosion age of 90 days. (a) P0 specimens; (b) P10 specimens; (c) P25 specimens.
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Figure 6. Proportion of holes with an erosion age of 90 days. (a) P0 specimens; (b) P10 specimens; (c) P25 specimens.
Figure 6. Proportion of holes with an erosion age of 90 days. (a) P0 specimens; (b) P10 specimens; (c) P25 specimens.
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Figure 7. Appearance of specimens under 100 freeze–thaw cycles. (a) P0 specimens; (b) P10 specimens; (c) P25 specimens.
Figure 7. Appearance of specimens under 100 freeze–thaw cycles. (a) P0 specimens; (b) P10 specimens; (c) P25 specimens.
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Figure 8. Proportion of holes under 100 freeze–thaw cycles. (a) P0 specimens; (b) P10 specimens; (c) P25 specimens.
Figure 8. Proportion of holes under 100 freeze–thaw cycles. (a) P0 specimens; (b) P10 specimens; (c) P25 specimens.
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Figure 9. Variation curve of compressive strength corrosion resistance coefficient. (a) F0 solution; (b) F1 solution; (c) F5 solution; (d) F10 solution.
Figure 9. Variation curve of compressive strength corrosion resistance coefficient. (a) F0 solution; (b) F1 solution; (c) F5 solution; (d) F10 solution.
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Figure 10. Variation curve of relative mass evaluation parameters. (a) F0 solution; (b) F1 solution; (c) F5 solution; (d) F10 solution.
Figure 10. Variation curve of relative mass evaluation parameters. (a) F0 solution; (b) F1 solution; (c) F5 solution; (d) F10 solution.
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Figure 11. Variation curve of relative dynamic elastic modulus evaluation parameters. (a) F0 solution; (b) F1 solution; (c) F5 solution; (d) F10 solution.
Figure 11. Variation curve of relative dynamic elastic modulus evaluation parameters. (a) F0 solution; (b) F1 solution; (c) F5 solution; (d) F10 solution.
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Figure 12. Variation curve of mass under salt erosion and freeze–thaw coupling conditions. (a) Mass change curve; (b) relative mass change curve; (c) mass loss rate change curve.
Figure 12. Variation curve of mass under salt erosion and freeze–thaw coupling conditions. (a) Mass change curve; (b) relative mass change curve; (c) mass loss rate change curve.
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Figure 13. Variation curve of dynamic elastic modulus under salt erosion and freeze–thaw coupling conditions. (a) Dynamic elastic modulus change curve; (b) relative dynamic elastic modulus change curve; (c) dynamic elastic modulus loss rate change curve.
Figure 13. Variation curve of dynamic elastic modulus under salt erosion and freeze–thaw coupling conditions. (a) Dynamic elastic modulus change curve; (b) relative dynamic elastic modulus change curve; (c) dynamic elastic modulus loss rate change curve.
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Figure 14. Variation curve of flexural strength under salt erosion and freeze–thaw coupling conditions. (a) Flexural strength change curve; (b) relative flexural strength change curve; (c) flexural strength loss rate change curve.
Figure 14. Variation curve of flexural strength under salt erosion and freeze–thaw coupling conditions. (a) Flexural strength change curve; (b) relative flexural strength change curve; (c) flexural strength loss rate change curve.
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Figure 15. Relationship between flexural strength and dynamic elastic modulus. (a) Flexural strength vs. dynamic elastic modulus; (b) flexural strength loss rate vs. dynamic elastic modulus loss rate.
Figure 15. Relationship between flexural strength and dynamic elastic modulus. (a) Flexural strength vs. dynamic elastic modulus; (b) flexural strength loss rate vs. dynamic elastic modulus loss rate.
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Figure 16. Microstructure of specimens with an erosion age of 30 days and 120 days. (a) P0 specimens; (b) P10 specimens; (c) P25 specimens.
Figure 16. Microstructure of specimens with an erosion age of 30 days and 120 days. (a) P0 specimens; (b) P10 specimens; (c) P25 specimens.
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Figure 17. Microstructure of specimens after 25 and 100 cycles of salting-freeze–thaw coupling. (a) P0 specimens; (b) P10 specimens; (c) P25 specimens.
Figure 17. Microstructure of specimens after 25 and 100 cycles of salting-freeze–thaw coupling. (a) P0 specimens; (b) P10 specimens; (c) P25 specimens.
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Table 1. The relevant technical indicators of the water-based epoxy resin emulsion.
Table 1. The relevant technical indicators of the water-based epoxy resin emulsion.
TypeAppearanceSolid Content/%PH ValueEpoxide NumberViscosity/Pa.sDensity/g·cm−3
DY-128-50Milky white uniform liquid50 ± 36~80.52≤21.05
Table 2. The relevant technical indicators of the water-soluble modified epoxy curing agent.
Table 2. The relevant technical indicators of the water-soluble modified epoxy curing agent.
TypeAppearanceSolid Content/%PH ValueViscosity/Pa.sAmine Value
DY-175Light brown uniform liquid49~519.5~10.56.5~9330
Table 3. The proportion of concrete specimens.
Table 3. The proportion of concrete specimens.
GroupSpecimensEpoxy Resin Content
/%		Defoamer Content
/%		Cement
/kg·m−3		Sand
/kg·m−3		Coarse Aggregate
/kg·m−3		Water
/kg·m−3
No. 1P0003427041149205
No. 2P5513427041149205
No. 3P101013427041149205
No. 4P151513427041149205
No. 5P202013427041149205
No. 6P252513427041149205
Table 4. Ion content of saline soil on Daoxiang Road in Wensu County.
Table 4. Ion content of saline soil on Daoxiang Road in Wensu County.
Ion TypesSO42−/g·kg−1Mg2+/g·kg−1Cl−/g·kg−1CO32−/g·kg−1HCO3−/g·kg−1
Contents3.923.384.551.070.94
Table 5. Concentration of the composite salt solutions.
Table 5. Concentration of the composite salt solutions.
Solution NameTypes of SolutionsBaseline Salt Content/g·L−1Solution Concentration/%
NaClNa2CO3NaHCO3MgSO4Na2SO4
F0Pure Water000000
F1Reference Solution6.531.541.359.700.781.99
F55× Solution32.657.706.7548.503.909.95
F1010× Solution65.3015.4013.5097.007.8019.90
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Zhang, Z.; Zhang, F.; Wu, C.; Chen, Y. Experimental Study on the Performance of Sustainable Epoxy Resin-Modified Concrete Under Coupled Salt Corrosion and Freeze–Thaw Cycles. Sustainability 2025, 17, 6186. https://doi.org/10.3390/su17136186

AMA Style

Zhang Z, Zhang F, Wu C, Chen Y. Experimental Study on the Performance of Sustainable Epoxy Resin-Modified Concrete Under Coupled Salt Corrosion and Freeze–Thaw Cycles. Sustainability. 2025; 17(13):6186. https://doi.org/10.3390/su17136186

Chicago/Turabian Style

Zhang, Zhen, Fang Zhang, Chuangzhou Wu, and Yafei Chen. 2025. "Experimental Study on the Performance of Sustainable Epoxy Resin-Modified Concrete Under Coupled Salt Corrosion and Freeze–Thaw Cycles" Sustainability 17, no. 13: 6186. https://doi.org/10.3390/su17136186

APA Style

Zhang, Z., Zhang, F., Wu, C., & Chen, Y. (2025). Experimental Study on the Performance of Sustainable Epoxy Resin-Modified Concrete Under Coupled Salt Corrosion and Freeze–Thaw Cycles. Sustainability, 17(13), 6186. https://doi.org/10.3390/su17136186

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