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26 pages, 36055 KB

Open AccessArticle

Experimental Investigation on the Effect of Wetting–Drying Cycles on Bond Performance of GFRP Adhesive Anchors in Concrete

by Yifan Xu, Wensheng Liang, Xianghong Ding and Yanjie Wang

Buildings 2026, 16(9), 1649; https://doi.org/10.3390/buildings16091649 - 22 Apr 2026

Viewed by 299

Abstract

The long-term durability of adhesive anchors in aggressive environments is a critical concern for infrastructure safety, with steel corrosion being one of the most detrimental phenomena. While glass fiber-reinforced polymer (GFRP) anchors offer corrosion-resistant alternatives to steel anchors in harsh marine environments, the [...] Read more.

The long-term durability of adhesive anchors in aggressive environments is a critical concern for infrastructure safety, with steel corrosion being one of the most detrimental phenomena. While glass fiber-reinforced polymer (GFRP) anchors offer corrosion-resistant alternatives to steel anchors in harsh marine environments, the bond performance at the anchorage interface progressively deteriorates under wetting–drying (WD) cycles, which may compromise long-term anchorage integrity. However, the bond characteristics of GFRP anchors under WD exposure, particularly the development of predictive models, remain insufficiently understood. This paper presents an experimental investigation into the impact of WD cycles on the bond of GFRP adhesive anchors in concrete. Twenty-four specimens were tested under pull-out loads, considering two key variables: bonded length (40 mm and 80 mm, corresponding to 5 and 10 times the bar diameter) and number of WD cycles (0, 30, 60, and 90). Artificial seawater was prepared via ASTM D1141-98 to simulate marine exposure conditions. The results revealed that both bond strength and bond stiffness decreased significantly with increasing WD cycles, while the failure mode progressively shifted from the bar–adhesive interface to the adhesive–concrete interface. Based on the experimental data, a cycle-dependent bond strength model was developed to predict the bond degradation of the anchor–concrete interface after WD exposure. Requiring only the undegraded concrete strength, the proposed model effectively captures the coupled effects of WD cycles and bonded length on bond strength degradation, presenting a practical tool for the durability design and service life evaluation of GFRP anchorage systems in coastal and marine environments. Full article

(This article belongs to the Special Issue Development and Application of Concrete Materials and Related Building Materials)

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14 pages, 2863 KB

Open AccessArticle

Influence of Saline–Alkali Water with Different Salt Compositions on Drying Shrinkage and Early Strength of Cement-Based Materials

by Yuxian Chen, Shiyu Zhang, Pengcheng Shen, Yongyan Chu, Shubin Zhou and Yang Zhou

Buildings 2026, 16(3), 612; https://doi.org/10.3390/buildings16030612 - 2 Feb 2026

Viewed by 394

Abstract

This study systematically investigates the effects of varying Cl⁻/

{S O}_{4}^{2 -}

concentration ratios in saline solutions on the drying shrinkage, mechanical properties, and microstructure evolution of a cementitious system under simulated saline–alkali conditions. The underlying influence mechanism is [...] Read more.

This study systematically investigates the effects of varying Cl⁻/

{S O}_{4}^{2 -}

concentration ratios in saline solutions on the drying shrinkage, mechanical properties, and microstructure evolution of a cementitious system under simulated saline–alkali conditions. The underlying influence mechanism is elucidated via TG-DTG, XRD, and SEM analyses. Experimental results indicate that increasing the Cl⁻/

{S O}_{4}^{2 -}

concentration ratio of the mixing water from 0.2 to 2.5 leads to a significant rise in early-age drying shrinkage, with an increase of approximately 19%, while it simultaneously enhances the early-age compressive strength of the cementitious matrix, achieving increases of approximately 13% at 1 d, 14% at 3 d, 14% at 7 d, and stabilizing at about 7% by 28 d. Microscopic characterizations reveal that as the Cl⁻/

{S O}_{4}^{2 -}

concentration ratio increases, the ettringite content decreases, the contents of Friedel’s salt and calcium hydroxide increase, and the cementitious microstructure accordingly becomes denser. This work aims to provide theoretical and experimental references for the durability design and performance optimization of cement-based materials in saline–alkali regions. Full article

(This article belongs to the Special Issue Development and Application of Concrete Materials and Related Building Materials)

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28 pages, 4499 KB

Open AccessArticle

Analytical and Experimental Study on Bond Behavior of Embedded Through-Section FRP Bar-to-Concrete Joints Using a Trilinear Cohesive Material Law

by Wensheng Liang, Jiang Lu, Jinping Fu, Bi Zhang, Baowen Zhang and Yanjie Wang

Buildings 2026, 16(1), 164; https://doi.org/10.3390/buildings16010164 - 29 Dec 2025

Cited by 1 | Viewed by 504

Abstract

The embedded through-section (ETS) technique is a promising method for fiber-reinforced polymer (FRP)-strengthening reinforced concrete (RC) structures, offering higher bond resistance and reduced surface preparation compared to externally bonded or near-surface mounted FRP systems. A common failure in ETS applications is debonding at [...] Read more.

The embedded through-section (ETS) technique is a promising method for fiber-reinforced polymer (FRP)-strengthening reinforced concrete (RC) structures, offering higher bond resistance and reduced surface preparation compared to externally bonded or near-surface mounted FRP systems. A common failure in ETS applications is debonding at the FRP bar-to-concrete interface. However, current design standards often assume uniform bond stress and lack predictive models that account for debonding propagation and its effect on load capacity. Furthermore, a detailed analysis of interfacial stress development, including debonding initiation and progression along varying bond lengths, remains limited. To address these gaps, this study introduces an analytical model that describes the complete debonding process in ETS FRP bar-to-concrete joints, incorporating both long and short bond lengths and frictional effects. Based on a trilinear cohesive material law (CML), closed-form expressions are deduced for the load–slip response, maximum load, interfacial shear stress and strain distribution along the FRP bar. The proposed model is validated experimentally through pull-out tests on glass FRP (GFRP) bars adhesively bonded to concrete with different strength grades. The results show that the analytical predictions agree well with both the self-conducted experimental data for short joints and existing test results for long joints given in the literature. Therefore, the developed design-oriented solution enables accurate evaluation of the actual contribution of ETS FRP reinforcement to RC members by explicitly modeling debonding behavior. This provides a rigorous and mechanics-based tool for performance-based design of ETS FRP-to-concrete joints, addressing a critical gap in the future refinement of current design standards. Full article

(This article belongs to the Special Issue Development and Application of Concrete Materials and Related Building Materials)

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20 pages, 2947 KB

Open AccessArticle

Influence of Nano-Silica and Porosity on the Strength and Permeability of Permeable Concrete: An Experimental Study

by Jinping Fu, Lu Jiang, Mingjian Yang, Desun Yu, Minghao Shen and Yanjie Wang

Buildings 2026, 16(1), 148; https://doi.org/10.3390/buildings16010148 - 29 Dec 2025

Cited by 2 | Viewed by 579

Abstract

Strength and the permeability coefficient are recognized as the two main design parameters for permeable concrete. Although adding an appropriate amount of nano-silica (NS) can enhance the slurry strength and enhance the bond between the aggregate and cementitious material, research on the combined [...] Read more.

Strength and the permeability coefficient are recognized as the two main design parameters for permeable concrete. Although adding an appropriate amount of nano-silica (NS) can enhance the slurry strength and enhance the bond between the aggregate and cementitious material, research on the combined effects of porosity and NS on the behavior of permeable concrete is limited. An experimental program was carried out to demonstrate the impact of NS on the permeability (K) and strength (f_c) of permeable concrete. The tested variables included the NS content (0, 0.5, 1.0, 1.5, 2.0, and 2.5%) and the porosity (p = 15, 20, and 25%), following the identification of an optimal water-to-binder (w/b) ratio of 0.3. It was found that the addition of NS alters the failure mechanism by transferring the critical failure location from the cementitious matrix to aggregate particles. An additive of 1% NS shows the most significant enhancement in the concrete strength, with improvement efficacy increasing substantially with the porosity. Specifically, the 28-day strength of permeable concrete modified with 1% NS increased by 6.4%, 16.1%, and 38.5% for mixes with 15%, 20%, and 25% porosity, respectively. Meanwhile, NS improves the permeability with 0.5% dosage, providing the most effective enhancement. Finally, an empirical expression between permeability and porosity was developed based on the test results, which allows engineers to calculate the required porosity (e.g., p ≈ 17% for K = 1.0 cm/s) to meet specific permeability in pavement applications. Full article

(This article belongs to the Special Issue Development and Application of Concrete Materials and Related Building Materials)

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21 pages, 4348 KB

Open AccessArticle

Numerical and Experimental Investigation on Time-Dependent Crack Extension in Concrete Under Sustained Loads

by Zheng Yao, Jiacheng Dong, Linmei Wu, Zetong Li, Ziheng Chang, Zhuohui Yu and Binze Jiang

Buildings 2025, 15(22), 4180; https://doi.org/10.3390/buildings15224180 - 19 Nov 2025

Viewed by 687

Abstract

For concrete structures dominated by fracture failure, e.g., containment and gravity dams, sustained load deformations primarily arise from crack extension and concrete viscoelasticity. As cracks progressively grow under sustained loads, accurate prediction of the time-dependent fracture process in concrete accounting for crack-viscoelasticity interactions [...] Read more.

For concrete structures dominated by fracture failure, e.g., containment and gravity dams, sustained load deformations primarily arise from crack extension and concrete viscoelasticity. As cracks progressively grow under sustained loads, accurate prediction of the time-dependent fracture process in concrete accounting for crack-viscoelasticity interactions are crucial for the stability and safe design of concrete structures. This paper presents an initial fracture toughness (

K_{IC}^{i n i}

)-based numerical model to predict the time-dependent crack extension in concrete under sustained loads. The model integrates a time-dependent tension-softening constitutive relation, the generalized Kelvin chain model for viscoelastic behavior and

K_{IC}^{i n i}

-based criterion for crack extension. The accuracy of the model was verified with two sets of experimental data available in the literature. The results indicated that the tension-softening constitutive law that quantifies the relation cohesive stress (s_w), loading time (t), and COD can be successfully implemented in the numerical model. The predicted CMOD versus time and crack length versus time curves show good agreements with the test results regardless of loading level, specimen configuration and material property, demonstrating the predictive capability of the model in describing the crack extension in concrete exposed to sustained loads. Full article

(This article belongs to the Special Issue Development and Application of Concrete Materials and Related Building Materials)

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18 pages, 7738 KB

Open AccessArticle

Hybrid Fiber-Reinforced Concrete with Polypropylene and Steel Fibers in 3D Reinforcement Frameworks

by Glykeria Porfyriadou, Dimitrios Moschovas, Dimitrios Exarchos, Panagiotis Papageorgiou, Konstantinos G. Kolovos, Theodore E. Matikas and Nikolaos E. Zafeiropoulos

Buildings 2025, 15(22), 4028; https://doi.org/10.3390/buildings15224028 - 8 Nov 2025

Cited by 1 | Viewed by 1659

Abstract

This study investigates an alternative methodology for incorporating polymeric and steel fibers into concrete. Conventional reinforcement approaches often require complex application techniques and face industrial limitations. In contrast, the present work evaluates the use of short, discontinuous fibers—commercial polypropylene fibers (PFRC), polypropylene fiber [...] Read more.

This study investigates an alternative methodology for incorporating polymeric and steel fibers into concrete. Conventional reinforcement approaches often require complex application techniques and face industrial limitations. In contrast, the present work evaluates the use of short, discontinuous fibers—commercial polypropylene fibers (PFRC), polypropylene fiber braid (PFBRC) and steel fibers (SFRC)—which enable improved dispersion, ease of mixing and potential mechanical benefits. The fibers were randomly oriented and evenly distributed within the cementitious matrix. Mechanical performance was assessed through four-point bending tests combined with displacement measurements, acoustic emission analysis and uniaxial compression tests, while scanning electron microscopy (SEM) confirmed fiber–matrix interaction and fragment retention. The results demonstrated significant improvements, with compressive strength exceeding that of unreinforced concrete, while hybrid fiber systems provided enhanced crack resistance and post-cracking stability. Overall, the findings highlight that the integration of discontinuous fibers may provide tangible mechanical advantages, potentially outweighing the structural benefits of continuous reinforcing bars in applications requiring high strength and reliable mechanical performance. Full article

(This article belongs to the Special Issue Development and Application of Concrete Materials and Related Building Materials)

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17 pages, 8973 KB

Open AccessArticle

Experimental Research on Mechanical Behaviour of Precast Concrete Shear Walls with Horizontal Joint Quality Defects

by Mingjin Chu, Zhiqiang Zhang, Jiliang Liu, Shengtao Wu and Chao Dong

Buildings 2025, 15(21), 3951; https://doi.org/10.3390/buildings15213951 - 2 Nov 2025

Viewed by 788

Abstract

In precast concrete shear wall structures, the joints formed during the vertical connection of precast units are referred to as the “horizontal joint”. Serving as vertical connection nodes in this structure system, the construction quality of theses horizontal joints significantly influences the structural [...] Read more.

In precast concrete shear wall structures, the joints formed during the vertical connection of precast units are referred to as the “horizontal joint”. Serving as vertical connection nodes in this structure system, the construction quality of theses horizontal joints significantly influences the structural integrity. To investigate the influence of horizontal joint quality defects on the mechanical behaviour of precast concrete shear walls, three precast concrete shear wall specimens with quality defects in different regions and three control specimens were designed. Quasi-static tests under a constant axial load were conducted to investigate the effects of defect area, location and other factors on the mechanical behaviour of the walls. Results demonstrate that the quality defects in horizontal joints significantly affect the mechanical behaviour of precast concrete shear walls. When the ratio of the quality defect area to the cross-sectional area of the boundary member reaches 100%, the yield load and peak load of the precast concrete shear wall decrease by 13% and 20%, respectively. Additionally, the structural stiffness exhibited a 13% degradation at a drift angle of 1/1000. Although the failure mode remains largely unchanged, yielding of longitudinal reinforcement in the boundary members is observed. Moreover, as the proportion of the quality defect area to the cross-sectional area decreases, its adverse effects on the mechanical behaviour of the precast concrete shear wall gradually diminish. The established numerical analysis model is shown to be reasonable and reliable. When the defective area of the horizontal joints is less than 25% of the total cross-sectional area, the quality defects essentially have no influence on the mechanical behaviour of the precast concrete shear walls. Full article

(This article belongs to the Special Issue Development and Application of Concrete Materials and Related Building Materials)

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19 pages, 3765 KB

Open AccessArticle

Thermal Effects on Main Girders During Construction of Composite Cable-Stayed Bridges Based on Monitoring Data

by Hua Luo, Wan Wu, Qincong She, Bin Li, Chen Yang and Yahua Pan

Buildings 2025, 15(17), 2990; https://doi.org/10.3390/buildings15172990 - 22 Aug 2025

Cited by 1 | Viewed by 1382

Abstract

Thermal effects critically influence the design and construction of steel-concrete composite cable-stayed bridges, where material thermal mismatch complicates structural responses. Current code-specified temperature gradient models inadequately address long-span bridges. This study employs in-situ monitoring of the Chibi Yangtze River Bridge to propose a [...] Read more.

Thermal effects critically influence the design and construction of steel-concrete composite cable-stayed bridges, where material thermal mismatch complicates structural responses. Current code-specified temperature gradient models inadequately address long-span bridges. This study employs in-situ monitoring of the Chibi Yangtze River Bridge to propose a refined vertical temperature gradient model, utilizing an exponential function for the concrete deck and a linear function for the steel web. Finite element analysis across six construction stages reveals: (1) Under negative temperature gradients, the concrete deck develops tensile stresses (2.439–2.591 MPa), approximately 30% lower than code-predicted values (3.613–3.715 MPa), highlighting risks of longitudinal cracking. (2) At the maximum double-cantilever stage, transverse stress distributions show pronounced shear lag effects, positive shear lag in deck sections connected to crossbeams and negative shear lag in non-connected sections. The proposed model reduces tensile stress conservatism in codes by 30–33%, enhancing prediction accuracy for composite girders. This work provides critical insights for thermal effect management in long-span bridge construction. Full article

(This article belongs to the Special Issue Development and Application of Concrete Materials and Related Building Materials)

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