Materials

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30 pages, 3637 KB

Open AccessArticle

A Hybrid-Dimensional Iterative Coupled Modeling of Lubrication Flow in Deformable Geological Media with Discrete Fracture Networks

by Yue Xu, Tao You and Qizhi Zhu

Materials 2026, 19(7), 1444; https://doi.org/10.3390/ma19071444 - 4 Apr 2026

Viewed by 259

Abstract

Fluid-driven fracture processes are central to the development of subsurface energy systems such as geothermal and hydrocarbon reservoirs. Although phase-field formulations have become a widely used tool for describing fracture initiation and growth, the diffuse representation of cracks makes it difficult to resolve [...] Read more.

Fluid-driven fracture processes are central to the development of subsurface energy systems such as geothermal and hydrocarbon reservoirs. Although phase-field formulations have become a widely used tool for describing fracture initiation and growth, the diffuse representation of cracks makes it difficult to resolve flow behavior accurately inside discrete fracture networks (DFNs) and to represent hydro-mechanical coupling in a sharp-interface sense. This study develops a hybrid-dimensional iterative framework for lubrication-flow simulation in deformable fractured geomaterials. By leveraging phase-field point clouds together with non-conforming discretization schemes for both the solid matrix and fracture domains, the proposed framework enables the dynamic reconstruction of evolving fracture networks. The theoretical formulation and numerical implementation of the coupling strategy are presented in detail. Hydraulic benchmark examples verify the performance of the fluid flow solver under various physical conditions. The classical Sneddon problem and Khristianovic–Geertsma–de Klerk (KGD) model are employed to validate the solid deformation solver, confirming accurate predictions of crack opening displacement and mesh independence in fracture width calculation. Additional simulations with complex pre-existing fracture patterns further demonstrate the applicability of the framework to coupled hydro-mechanical analysis in fractured media. Full article

(This article belongs to the Special Issue Advances in Material Structural Analysis: Finite Element Analysis and Numerical Modelling)

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27 pages, 7143 KB

Open AccessArticle

Research on Material Optimization of CSM Method Structures in Highly Weathered Strata

by Yifan Xie, Haitao Liu, Hao Wen, Chuangui Sun, Yong Chang, Qiang Feng, Lianzhen Zhang and Hongbo Wang

Materials 2026, 19(7), 1287; https://doi.org/10.3390/ma19071287 - 24 Mar 2026

Viewed by 184

Abstract

To address the challenges of low strength and poor impermeability of soil–cement walls formed with ordinary cement materials when applying the CSM (Cutter Soil Mixing) method in highly weathered strata, this study carried out structural optimization by combining the CSM method with H–section [...] Read more.

To address the challenges of low strength and poor impermeability of soil–cement walls formed with ordinary cement materials when applying the CSM (Cutter Soil Mixing) method in highly weathered strata, this study carried out structural optimization by combining the CSM method with H–section steel. This optimization effectively resolves issues such as low efficiency and high cost associated with the CSM method integrated with cement–filled piles. Meanwhile, using ordinary Portland cement as the base material, basalt fiber, sodium bentonite, and fly ash were added to investigate the influence of each component on the performance of the new composite. A novel CSM material suitable for highly weathered strata was developed, which exhibits excellent mechanical strength and impermeability. The optimal mix proportion of the soil–cement material was determined as follows: basalt fiber 0.5%, fly ash 15%, and sodium bentonite 3%. This research provides a quantitative basis for the efficient and economical application of the CSM method in highly weathered strata. Full article

(This article belongs to the Special Issue Advances in Material Structural Analysis: Finite Element Analysis and Numerical Modelling)

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17 pages, 2575 KB

Open AccessArticle

Research and Development of Cement-Based Dynamic Water Grouting Material for the CSM Construction Method

by Zhigang Yang, Fansheng Zhang, Yong Chang, Xihao Yang, Jianjian Li, Qiang Feng, Hongbo Wang and Hao Tong

Materials 2026, 19(6), 1167; https://doi.org/10.3390/ma19061167 - 17 Mar 2026

Viewed by 305

Abstract

Cutter soil mixing (CSM) is a widely adopted construction technique for forming waterproof diaphragm walls in underground engineering. However, cement slurry is prone to dispersion loss and performance degradation in moving water, making it difficult to meet engineering requirements. In this study, based [...] Read more.

Cutter soil mixing (CSM) is a widely adopted construction technique for forming waterproof diaphragm walls in underground engineering. However, cement slurry is prone to dispersion loss and performance degradation in moving water, making it difficult to meet engineering requirements. In this study, based on the characteristics of the CSM method in dynamic water environments, ordinary Portland cement is used as the main material, and hydroxypropyl methyl cellulose (HPMC), redispersible latex powder, polypropylene fiber and a polyether defoamer are added to improve it. The influence of each component on the performance of the new material is investigated, and a new CSM material suitable for dynamic water environments is developed. The material has good stability and suitable fluidity, controllable setting time, good anti-dispersion performance in dynamic water. The optimal mix ratio is as follows: water–cement ratio of 1; HPMC 1.4%; redispersible latex powder 3%; polypropylene fiber 0.4%; and polyether defoamer 0.8%. Field tests show that the new grouting material applied to CSM waterproof curtain construction results in a leak-free wall with excellent waterproofing performance, which verifies its engineering feasibility and provides a technical reference for the application of the CSM method in dynamic water environments. Full article

(This article belongs to the Special Issue Advances in Material Structural Analysis: Finite Element Analysis and Numerical Modelling)

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26 pages, 6439 KB

Open AccessFeature PaperArticle

The Durability Assessment Methodology of Power Engineering Equipment Under Thermo-Mechanical Fatigue Using the Example of the HR6W Alloy

by Michał Paduchowicz, Tomasz Dobosz and Artur Górski

Materials 2026, 19(5), 891; https://doi.org/10.3390/ma19050891 - 27 Feb 2026

Viewed by 212

Abstract

This article presents an innovative methodology for assessing the durability of power engineering components under thermo-mechanical fatigue conditions. The approach integrates laboratory low-cycle fatigue tests of alloy specimens at elevated temperatures, measurements of working-medium parameters obtained from operating industrial equipment, and numerical simulations [...] Read more.

This article presents an innovative methodology for assessing the durability of power engineering components under thermo-mechanical fatigue conditions. The approach integrates laboratory low-cycle fatigue tests of alloy specimens at elevated temperatures, measurements of working-medium parameters obtained from operating industrial equipment, and numerical simulations performed using the finite element method. Durability is estimated on the basis of curves describing the relationships between critical parameters such as the Coffin–Manson and Ostergren parameters and the number of cycles to failure. Within the region of the structure identified as the most susceptible to fatigue damage, the orientation of the critical plane is determined with respect to the corresponding criterion functions. This allows the calculated criterion values to be correlated with experimental data, enabling the determination of the incremental durability loss of the component. The proposed methodology is distinguished by its practical applicability and the possibility of incorporating both proprietary fatigue test results and data reported in the literature. Full article

(This article belongs to the Special Issue Advances in Material Structural Analysis: Finite Element Analysis and Numerical Modelling)

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27 pages, 5571 KB

Open AccessArticle

Simulation Analysis of Thermal Deformation and Extruded Profile Formability of Al–10Mg–3Zn Aluminum Alloy

by Guanmei Niu, Wei Li, Kaidi Jiang, Yang Yang, Guojun Wang, Cheng Liu and Linzhong Zhuang

Materials 2026, 19(2), 375; https://doi.org/10.3390/ma19020375 - 17 Jan 2026

Cited by 1 | Viewed by 517

Abstract

To investigate the hot deformation characteristics of the Al–10Mg–3Zn alloy, a series of hot compression tests was carried out using a Gleeble-3500 simulator. The experimental matrix covered temperatures of 300–450 °C and strain rates from 0.001 to 10 s⁻¹. The true [...] Read more.

To investigate the hot deformation characteristics of the Al–10Mg–3Zn alloy, a series of hot compression tests was carried out using a Gleeble-3500 simulator. The experimental matrix covered temperatures of 300–450 °C and strain rates from 0.001 to 10 s⁻¹. The true stress–strain curves were obtained and the hot processing map of the alloy was constructed based on the Dynamic Material Model principle. The multi-objective optimization of the extrusion process parameters was performed using the response surface method. The results showed that the flow stress of Al–10Mg–3Zn alloy increased with the increase in the strain rate and decreased with the increase in the deformation temperature, indicating that the alloy had a positive strain rate sensitivity. A strain-compensated Arrhenius constitutive model and a hot processing map of Al–10Mg–3Zn alloy were established based on the temperature-corrected data; here, the optimal temperature range and strain rate range for hot processing were specified. The optimal extrusion process parameters, determined by the response surface method, were as follows: billet temperature of 400 °C, extrusion speed of 0.20 mm/s, and ingot length of 350 mm. With this parameter combination, the simulation predicted an extrusion load of 73.29 MN, a velocity deviation of 24.96%, and a cross-sectional temperature difference of 9.48 °C for the profile. The predicted values from the response surface method were highly consistent with those from the finite element simulation. The optimized process parameters significantly reduced the extrusion load of the profile. Full article

(This article belongs to the Special Issue Advances in Material Structural Analysis: Finite Element Analysis and Numerical Modelling)

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22 pages, 5873 KB

Open AccessArticle

Research on Mechanical Properties of Nano-Modified Foam Concrete Improved by Micro-inCorporated Carbon Nanotubes

by Shukun Zhang, Peng Jiang, Haohao Wang, Dianzhi Feng and Hao Wang

Materials 2026, 19(1), 184; https://doi.org/10.3390/ma19010184 - 4 Jan 2026

Viewed by 391

Abstract

Foamed concrete is a lightweight, environmentally friendly civil engineering material with excellent absorption capacity. It has been widely applied in engineering fields such as building thermal insulation and pore filling of underground buried pipelines. But the mechanical properties of existing foamed concrete cannot [...] Read more.

Foamed concrete is a lightweight, environmentally friendly civil engineering material with excellent absorption capacity. It has been widely applied in engineering fields such as building thermal insulation and pore filling of underground buried pipelines. But the mechanical properties of existing foamed concrete cannot meet the engineering requirements for support, pressure relief and filling of weak surrounding rock. The mechanical properties of foamed concrete were improved with CNTs to prepare CNT foamed concrete (CNTFC) pressure-relieving filling materials. The effects of five factors (the fly ash (FA) incorporation rate, aggregate–cement ratio, water–binder ratio, CNT incorporation rate and foam volume fraction) on the density and 2:1 cylinder strength (the ratio of uniaxial compressive strength to apparent density), splitting tensile (the ratio of splitting tensile strength to apparent density) and specific strength of the CNTFC were analyzed. By combining stress–strain and scanning electron microscopy analyses, the mechanism of improvement of the mechanical strength of CNTFC due to CNTs was clarified. The results show that the foam volume fraction, water–binder ratio and aggregate–cement ratio are the top three factors affecting its strength, followed by the CNT incorporation rate and FA incorporation rate. Among the five influencing factors, only the incorporation of CNTs increases the 2:1 cylinder strength, splitting tensile strength and specific strength. When the doping rate is 0.05%, this ratio specifically refers to the mass of CNTs accounting for 0.05% of the mass of the total cementitious materials of cement and fly ash. At this doping dosage, compared with the condition without CNTs (0% doping dosage), the uniaxial compressive strength increased from 6.23 MPa to 7.18 MPa (with an increase rate of 15.3%). The splitting tensile strength increased from 0.958 MPa to 1.02 MPa (with an increase rate of 6.5%). The density only slightly increased from 0.98 g/cm³ to 1.0 g/cm³ (with an increase rate of 2.0%), achieving the balance of “high strength-low density”. CNTs and cement hydrates are interwoven into a network structure, and the mechanical properties of the CNTFC are effectively improved by the excellent nanoscopic tensile properties. Excessive doping of CNTs takes 0.05% as the threshold. Exceeding this doping dosage (such as 0.10% and 0.15%) leads to a decrease in its strength and ductility due to CNT agglomeration and deterioration of pore structure. And 0.05% is the ratio of the mass of CNTs to the total cementitious materials of cement and fly ash. At this doping dosage, CNTs are uniformly dispersed and can balance the strength and density of CNTFC. The optimum proportion of CNTs is 0.05%. Full article

(This article belongs to the Special Issue Advances in Material Structural Analysis: Finite Element Analysis and Numerical Modelling)

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19 pages, 2651 KB

Open AccessArticle

Material Behavior and Computational Validation of Deep CO₂ Closed-Loop Geothermal Systems in Carbonate Reservoirs

by Xinghui Wu, Peng Li, Meifeng Cai, Tingting Jiang, Bolin Mu, Wanlei Su, Min Wang and Chunxiao Li

Materials 2025, 18(22), 5144; https://doi.org/10.3390/ma18225144 - 12 Nov 2025

Cited by 1 | Viewed by 672

Abstract

Closed-loop geothermal systems (CLGSs) avoid groundwater production and offer stable deep heat supply, but their long-term performance hinges on reliable coupling between the wellbore, the near-well interface and the surrounding formation. Using the D22 well in the Xiongan New Area (deep carbonate reservoir), [...] Read more.

Closed-loop geothermal systems (CLGSs) avoid groundwater production and offer stable deep heat supply, but their long-term performance hinges on reliable coupling between the wellbore, the near-well interface and the surrounding formation. Using the D22 well in the Xiongan New Area (deep carbonate reservoir), we built a three-domain thermo-hydraulic framework that updates CO₂ properties with temperature and pressure and explicitly accounts for wellbore-formation thermal resistance. Two geometries (U-tube and single-well coaxial) and two working fluids (CO₂ and water) were compared and optimized under field constraints. With the coaxial configuration, CO₂ delivers an average thermal power of 186.3 kW, exceeding that of water by 44.9%, while the fraction of wellbore heat loss drops by 3–5%. Under field-matched conditions, the predicted outlet temperature (76.8 °C) agrees with the measured value (77.2 °C) within 0.52%, confirming the value of field calibration for parameter transferability. Long-term simulations indicate that after 30 years of continuous operation the outlet temperature decline remains <8 °C for CO₂, outperforming water and implying better reservoir utilization and supply stability. Sensitivity and Pareto analyses identify a practical operating window, i.e., flow velocity of 0.9–1.1 m s⁻¹ and depth of 3000–3500 m, favoring the single-well coaxial + CO₂ scheme. These results show how field-calibrated modeling narrows uncertainty and yields implementable guidance on geometry, operating conditions, and wellbore insulation strategy. This study provides quantitative evidence that CO₂-CLGSs in deep carbonate formations can simultaneously increase thermal output and limit long-term decline, supporting near-term engineering deployment. Full article

(This article belongs to the Special Issue Advances in Material Structural Analysis: Finite Element Analysis and Numerical Modelling)

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20 pages, 4631 KB

Open AccessArticle

Research on Optimizing the Steel Fiber/CSH Interface Performance Based on Ca/Si Ratio

by Yalin Luan, Yongmei Wu, Runan Wang, Dongbo Cai, Lianzhen Zhang and Pengxiang Luan

Materials 2025, 18(17), 4049; https://doi.org/10.3390/ma18174049 - 29 Aug 2025

Cited by 1 | Viewed by 873

Abstract

Steel fiber reinforced concrete in marine environments often suffers from stress corrosion coupling. Under mechanical loading, the formation of penetrating cracks in the matrix increases susceptibility to seawater penetration and interfacial degradation. Using molecular dynamics simulations, this study investigated the effects of calcium-to-silicon [...] Read more.

Steel fiber reinforced concrete in marine environments often suffers from stress corrosion coupling. Under mechanical loading, the formation of penetrating cracks in the matrix increases susceptibility to seawater penetration and interfacial degradation. Using molecular dynamics simulations, this study investigated the effects of calcium-to-silicon (Ca/Si) ratios on the interfacial bonding and transport properties of a γ-FeOOH/CSH system. The results show that higher Ca/Si ratios strengthen ionic bonding between CSH and γ-FeOOH, thereby improving interfacial adhesion. Additionally, increased Ca/Si ratios significantly slow the transport of water molecules and ions (Na⁺, Cl⁻, SO₄²⁻) within γ-FeOOH/CSH nanopores. It was observed that Cl⁻ and SO₄²⁻ exhibited pronounced filtration effects at Ca/Si = 2.0. These findings suggest that optimizing the Ca/Si ratio in concrete can simultaneously enhance interfacial strength and reduce permeability. This provides an effective strategy for improving the marine erosion resistance of steel fiber reinforced concrete structures. Full article

(This article belongs to the Special Issue Advances in Material Structural Analysis: Finite Element Analysis and Numerical Modelling)

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22 pages, 5951 KB

Open AccessArticle

Experimental Study on the Filtration of Seawater Bentonite Slurry Under the Cutting Influence of Shield Cutterhead

by Deming Wang, Zhipeng Li, Qingsong Zhang, Lianzhen Zhang, Yang Gao, Hongzhen Dong, Yirui Li, Yueyue Wu and Yongqi Dai

Materials 2025, 18(17), 4025; https://doi.org/10.3390/ma18174025 - 28 Aug 2025

Viewed by 956

Abstract

Slurry shields maintain excavation face stability by forming a sealing filter cake through pressurized slurry filtration, though cutterhead rotation inevitably compromises this integrity. This study investigates seawater-based slurry filtration behavior under cutterhead disturbance using model testing, utilizing the effective support force conversion rate [...] Read more.

Slurry shields maintain excavation face stability by forming a sealing filter cake through pressurized slurry filtration, though cutterhead rotation inevitably compromises this integrity. This study investigates seawater-based slurry filtration behavior under cutterhead disturbance using model testing, utilizing the effective support force conversion rate to quantify the filter cake formation efficiency. Quantitative analysis evaluated key slurry constituents—bentonite, carboxymethyl cellulose (CMC), and fine sand (content/particle size)—and operational parameters including cutterhead rotation speed, advance rate, and slurry pressure. Results demonstrate enhanced conversion rate and stability with increased bentonite, CMC, and fine sand content; reduced fine sand particle size; elevated slurry pressure; and decreased cutterhead speed/advance rate. Nonlinear relationships exist between bentonite content and fine sand particle size, on the one hand, and the mean conversion rate and its fluctuation range, on the other. Stratum permeability and slurry pressure exhibit nonlinear effects on fluctuation range but linear relationships with mean value, indicating marginal impacts on support force magnitude and operational stability. Sensitivity analysis confirms bentonite as the dominant influencing factor, followed by cutterhead speed and CMC. Full article

(This article belongs to the Special Issue Advances in Material Structural Analysis: Finite Element Analysis and Numerical Modelling)

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17 pages, 4660 KB

Open AccessArticle

Development of Fault Similar Material for Model Test of Fault Water Inrush Disaster

by Zhipeng Li, Deming Wang, Kai Wang, Qingsong Zhang, Lianzhen Zhang, Yang Gao and Yongqi Dai

Materials 2025, 18(16), 3745; https://doi.org/10.3390/ma18163745 - 11 Aug 2025

Viewed by 749

Abstract

The applicability of similar materials is a key factor affecting the results of geomechanical model tests. In order to investigate the multi-physical field evolution mechanism of surrounding rocks during water inrush disasters in tunnels crossing fault zones, based on the similarity theory of [...] Read more.

The applicability of similar materials is a key factor affecting the results of geomechanical model tests. In order to investigate the multi-physical field evolution mechanism of surrounding rocks during water inrush disasters in tunnels crossing fault zones, based on the similarity theory of geomechanical model tests, the physical–mechanical parameters of a prototype rock’s mass were first analyzed for similarity, and the target values of similar materials were determined. Secondly, using sand as coarse aggregate, talcum powder as fine aggregate, gypsum and clay as binders, and Vaseline as a regulator, a fault-simulating material suitable for model tests was developed through extensive laboratory experiments. Finally, with material deformation characteristics and strength failure characteristics as key control indicators, parameters such as uniaxial compressive strength, permeability coefficient, unit weight, and elastic modulus are synergistically regulated to determine the influence of different component ratios on material properties. The experimental results show that the uniaxial compressive strength and permeability coefficient of similar materials are mainly controlled by gypsum and Vaseline. Cohesion is mainly controlled by clay and Vaseline. The application of this similar material in the model test of the tunnel fault water inrush disaster successfully reproduced the disaster evolution process of fault water inrush, meeting the requirements of the model test for similar materials of faults. Furthermore, it provides valuable guidance for the selection of similar materials and the optimization of mix proportions for fault disaster model tests involving similar characteristics. Full article

(This article belongs to the Special Issue Advances in Material Structural Analysis: Finite Element Analysis and Numerical Modelling)

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22 pages, 6497 KB

Open AccessArticle

Experimental Study and Application of TPO Waterproofing Membrane Lapping Process Parameters

by Keyong Wang, Zhenhua Zang, Jie Li, Zhenyue Shi, Mingcai Liu, Zhipeng Li, Qingbiao Wang, Yandong Shang, Chenglin Tian, Zifan Jia and Hui Wang

Materials 2025, 18(14), 3313; https://doi.org/10.3390/ma18143313 - 14 Jul 2025

Viewed by 1157

Abstract

Taking the TPO waterproofing membrane as an example, this paper studies the influence of temperature, speed and welding pressure on the welding quality of a TPO waterproofing membrane lap area through a peel test and a water impermeability test, determines the optimal construction [...] Read more.

Taking the TPO waterproofing membrane as an example, this paper studies the influence of temperature, speed and welding pressure on the welding quality of a TPO waterproofing membrane lap area through a peel test and a water impermeability test, determines the optimal construction process, and observes and compares the permeable path through laser confocal microscope. Finally, it is applied to the actual effect test in the project. The results show that the welding pressure test tool for the lap area of the waterproofing membrane is designed to meet the welding work test requirements of various lap areas of the waterproofing membrane. The peel strength increases first and then decreases with the increase in welding temperature, and the optimal construction temperature is 400 °C. The optimal construction speed is 4 m/min; at 400 °C welding temperature, the peel strength increases first and then decreases slightly with the increase in welding pressure. The optimal construction pressure is 14.97 N; under the condition of 0.2 MPa, 30 min to 0.6 MPa, 120 min, the water impermeability test of the overlapping area was qualified. In this paper, the optimal construction technology of a TPO waterproofing membrane is determined, which provides guidance for its application and promotion in engineering. Full article

(This article belongs to the Special Issue Advances in Material Structural Analysis: Finite Element Analysis and Numerical Modelling)

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27 pages, 2895 KB

Open AccessArticle

Experimental Study on the Preparation of Paste Filling Materials from Coal-Based Solid Wastes

by Chaowen Hu, Xiaojie Yang, Feng Zhang, Bo Pan, Ruifeng Huang, Bing Hu, Yongyuan Li, Lei Zhang, Bingshan Wang, Jianxun Gao, Huifeng Wang and Yun Yu

Materials 2025, 18(14), 3244; https://doi.org/10.3390/ma18143244 - 9 Jul 2025

Cited by 1 | Viewed by 971

Abstract

To reduce the cost of coal mine filling materials, a novel composite cementitious material was developed by utilizing coal-based solid waste materials, including fly ash, desulfurized gypsum, and carbide slag, along with cement and water as raw materials. Initially, a comprehensive analysis of [...] Read more.

To reduce the cost of coal mine filling materials, a novel composite cementitious material was developed by utilizing coal-based solid waste materials, including fly ash, desulfurized gypsum, and carbide slag, along with cement and water as raw materials. Initially, a comprehensive analysis of the physical and chemical properties of each raw material was conducted. Subsequently, proportioning tests were systematically carried out using the single-variable method. During these tests, multiple crucial performance indicators were measured. Specifically, the fluidity and bleeding rate of the slurry were evaluated to assess its workability, while the compressive strength and chemically bound water content of the hardened sample were tested to determine its mechanical properties and hydration degree. Through in-depth analysis of the test results, the optimal formulation of the composite cementitious material was determined. In the basic group, the mass ratio of fly ash to desulfurized gypsum was set at 70:30. In the additional group, the carbide slag addition amount accounted for 20% of the total mass, the cement addition amount was 15%, and the water–cement ratio was fixed at 0.65. Under these optimal proportioning conditions, the composite cementitious material exhibited excellent performance: its fluidity ranged from 180 to 220 mm, the bleeding rate within 6 h was less than 5%, and the 28-day compressive strength reached 17.69 MPa. The newly developed composite cementitious material features good fluidity and high strength of the hardened sample, fully meeting the requirements for mine filling materials. Full article

(This article belongs to the Special Issue Advances in Material Structural Analysis: Finite Element Analysis and Numerical Modelling)

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20 pages, 4425 KB

Open AccessArticle

Study on Similar Materials for Weakly Cemented Medium and Indoor Excavation Test

by Shanchao Hu, Lei Yang, Shihao Guo, Chenxi Zhang, Dawang Yin, Jinhao Dou and Yafei Cheng

Materials 2025, 18(13), 2948; https://doi.org/10.3390/ma18132948 - 22 Jun 2025

Cited by 1 | Viewed by 841

Abstract

The escalating disasters caused by the movement of shallow buried strata in China’s western mining areas are increasingly threatening operational safety. A critical issue in ensuring secure mining practices in these areas is the creep failure of weakly cemented soft rock under low-stress [...] Read more.

The escalating disasters caused by the movement of shallow buried strata in China’s western mining areas are increasingly threatening operational safety. A critical issue in ensuring secure mining practices in these areas is the creep failure of weakly cemented soft rock under low-stress conditions. The unique particle contact mechanisms in weakly cemented mudstone, combined with the persistence of the cemented materials and the particulate matter they form, lead to mechanical responses that differ significantly from those of typical soft rocks during loading. Building on an existing multivariate linear regression equation for new similar materials, this study developed qualified weakly cemented medium similar materials, offering appropriate materials for long-term creep tests of weakly cemented formations. This was accomplished by employing orthogonal proportioning tests. The principal findings of our investigation are as follows: The new, similar material exhibits low strength and prominent creep characteristics, accurately simulating weakly cemented materials in western mining areas. The concentration of rosin–alcohol solution has a measurable impact on key parameters, such as σ_c, E, and γ in the weakly cemented similar material specimens. Furthermore, the creep characteristics of the specimens diminish progressively with an increase in the proportion of iron powder (I) and barite powder (B). The material was applied to a similar indoor model test simulating the weakly cemented material surrounding the auxiliary haulage roadway in Panel 20314 of the Gaojialiang Coal Mine, with speckle analysis employed for detailed examination. The experimental findings suggest that both the conventional mechanical properties and long-term creep characteristics of the material align with the required specifications, offering robust support for achieving optimal outcomes in the similar model test. Full article

(This article belongs to the Special Issue Advances in Material Structural Analysis: Finite Element Analysis and Numerical Modelling)

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17 pages, 3550 KB

Open AccessArticle

Meso-Scale Breakage Characteristics of Recycling Construction and Demolition Waste Subgrade Material Under Compaction Effort

by Lu Han, Weiliang Gao, Yaping Tao and Lulu Liu

Materials 2025, 18(11), 2439; https://doi.org/10.3390/ma18112439 - 23 May 2025

Cited by 2 | Viewed by 809

Abstract

The application of construction and demolition waste (CDW) as roadbed filler faces challenges due to the variable mechanical properties caused by fragile recycled brick aggregates. This study elucidates the breakage mechanism of CDW fillers under compaction effort through a combination of standardized laboratory [...] Read more.

The application of construction and demolition waste (CDW) as roadbed filler faces challenges due to the variable mechanical properties caused by fragile recycled brick aggregates. This study elucidates the breakage mechanism of CDW fillers under compaction effort through a combination of standardized laboratory compaction tests and discrete element method (DEM) simulations. Furthermore, the breakage evolution patterns of mixed fills comprising recycled concrete and brick aggregates at various mixing ratios were revealed. A DEM model was developed to characterize recycled concrete and brick aggregates, adopting polygonal clumps for particles >4.75 mm and spherical clumps for finer fractions. The results indicate that particle breakage progresses through three distinct stages: linear fragment stage (0–200 kJ/m³, 50% of total breakage), deceleration growth stage (200–1000 kJ/m³, 38% of total breakage), and residual crushing stage (1000–2684.9 kJ/m³, 12% of total breakage). Recycled concrete aggregates form a skeleton restraining deep cracks, while brick aggregates enhance stability through energy dissipation and void filling. However, exceeding 30% brick content impedes skeleton development. Critically, a 30% brick content optimizes performance, achieving peak dry density with 25% lower compression deformation than concrete-only fillers, while limiting breakage index rise. These results provide a science-based strategy to optimize CDW roadbed design, improving recycling efficiency and supporting sustainable infrastructure. Full article

(This article belongs to the Special Issue Advances in Material Structural Analysis: Finite Element Analysis and Numerical Modelling)

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20 pages, 3979 KB

Open AccessArticle

Experimental Study on Shear Characteristics of Filled Joints Anchored by Basalt Fiber-Reinforced Polymer Materials

by Hengjie Luan, Qingzhai Shi, Changsheng Wang, Yujing Jiang, Sunhao Zhang, Jianrong Liu and Kun Liu

Materials 2025, 18(10), 2393; https://doi.org/10.3390/ma18102393 - 20 May 2025

Viewed by 961

Abstract

Filled joints are widely found in natural rock masses and are one of the main factors causing rock mass engineering instability. The use of bolts can effectively control the shear slip of filled joints, research on bolts filled joints in the filling degree, [...] Read more.

Filled joints are widely found in natural rock masses and are one of the main factors causing rock mass engineering instability. The use of bolts can effectively control the shear slip of filled joints, research on bolts filled joints in the filling degree, and other key parameters of the influence of the law, to ensure the stability of the engineering rock body is of great significance. This paper presents shear experiments on bolted filled joints of Basalt Fiber-Reinforced Polymer (BFRP) materials with different joint roughness and filling degrees, while acoustic emission technology monitors the shear failure process of the specimens. The results show that the peak shear strength decreases with the increase in filling degree, and the peak shear strength decreases by 23.9% when the filling degree changes from 0 to 2.0 at 4 MPa and J2 conditions, while the normal stress, the Joint Roughness Coefficient (JRC) and the peak shear strength both show a positive correlation. The normal deformation of bolted filled joints exhibits three distinct evolutionary patterns depending on the filling degree, while both JRC and normal stress significantly influence the magnitude of shear dilatancy-shrinkage deformation. The shear resistance of BFRP bolts is mainly reflected in the post-peak plastic stage, and some of the fibers break during its shear deformation to form controlled yielding, with vertical and horizontal deformation controlled within 15.5~22.3 mm and 4.7~6.9 mm, respectively. The Acoustic Emission (AE) results show that the AE events are mainly in the post-peak plasticity stage, and the proportion is about the sum of the proportion of the other two phases, and this proportion increases with the increase in the filling degree. Full article

(This article belongs to the Special Issue Advances in Material Structural Analysis: Finite Element Analysis and Numerical Modelling)

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17 pages, 1665 KB

Open AccessArticle

Evolution Mechanism of Filtration Characteristics of Cement Grouting Materials in Sandy Medium

by Xiao Feng, Shilei Zhang, Zhenzhong Shi, Qingsong Zhang, Meiling Li, Wenda Yang, Wen Sun and Benao Hou

Materials 2025, 18(10), 2385; https://doi.org/10.3390/ma18102385 - 20 May 2025

Cited by 1 | Viewed by 930

Abstract

The seepage diffusion of cement grouting materials into a sandy medium is influenced by the skeleton’s adsorption and the pore channels’ tortuosity, resulting in heterogeneous retention of cement particles during migration. This study established a theoretical model for the filtration coefficient based on [...] Read more.

The seepage diffusion of cement grouting materials into a sandy medium is influenced by the skeleton’s adsorption and the pore channels’ tortuosity, resulting in heterogeneous retention of cement particles during migration. This study established a theoretical model for the filtration coefficient based on the mass balance equation and linear filtration law. Grouting tests were conducted to determine the density of the cement slurry at various diffusion positions, and the filtration coefficient was calculated using the theoretical model. Results indicate that the filtration coefficient varies dynamically along the diffusion distance rather than remaining constant. The surface filtration range of Grade 42.5 Portland Cement slurry in sample S1 is approximately 30 cm, with a final diffusion distance of 190 cm. In contrast, the surface filtration ranges for the 800 mesh superfine cement in S2 and the 1250 mesh superfine cement in S3 are less than 10 cm, resulting in final diffusion distances of 69 cm and 87 cm, respectively. This demonstrates that a longer surface filtration range in the sand sample corresponds to a farther final diffusion distance of the slurry. Additionally, a larger ratio of sand pore diameter to cement particle size results in a smaller filtration coefficient and a greater slurry diffusion distance. Under a constant water–cement ratio, smaller cement particle sizes are associated with decreased slurry fluidity, which reduces the diffusion of cement slurry within the sandy medium. The research findings provide valuable insights for designing borehole spacing in grouting treatment for sandy media. Full article

(This article belongs to the Special Issue Advances in Material Structural Analysis: Finite Element Analysis and Numerical Modelling)

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22 pages, 11535 KB

Open AccessArticle

Transport Properties of Solutions in γ–FeOOH/CSH Pores of Steel Fiber-Reinforced Concrete (SFRC) Derived Using Molecular Dynamics

by Yalin Luan, Runan Wang, Changxin Huang, Andrey Jivkov and Lianzhen Zhang

Materials 2025, 18(10), 2176; https://doi.org/10.3390/ma18102176 - 8 May 2025

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Abstract

Steel fiber-reinforced concrete structures designed for marine environments can become compromised by the ingress of water and ions. Water and ion transport through the pores between steel fibers and concrete gels significantly affects the durability of such structures, but the mechanisms of this [...] Read more.

Steel fiber-reinforced concrete structures designed for marine environments can become compromised by the ingress of water and ions. Water and ion transport through the pores between steel fibers and concrete gels significantly affects the durability of such structures, but the mechanisms of this transport are not sufficiently understood. Reported here is a molecular dynamics-based investigation of the transport of water, NaCl, Na₂SO₄, and mixed solutions of NaCl and Na₂SO₄ through γ–FeOOH/CSH pores. The effect of pore width on the capillary transport of NaCl + Na₂SO₄ solutions was also investigated and reported. It is shown that the depth of water penetration in NaCl solution increases parabolically with time. It is further shown that the CSH surface forms bonds with different ions to form Na–O_CSH, Cl–Ca_CSH, and S–Ca_CSH compounds, which results in reduced rates of solution transport. The mixed NaCl + Na₂SO₄ solution was found to have the lowest transport rate. A reduction in pore width was found to reduce the transport rate of water molecules and diminish the transport of ions. In pores smaller than 2.5 nm in width, the immobilized ions aggregate into clusters, occupying pore inlets and blocking more ions from entering the channels. Compared with the matrix on both sides, solutions are transported significantly faster along the CSH side than along the γ–FeOOH side, indicating that the addition of steel fibers can effectively slow down the transport of water molecules and ions in concrete. These data on the difference in the transport of solutions along the two sides of the matrix may provide molecular-level insights to support studies on the durability of concrete materials. Full article

(This article belongs to the Special Issue Advances in Material Structural Analysis: Finite Element Analysis and Numerical Modelling)

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20 pages, 8770 KB

Open AccessArticle

Failure and Energy Evolution Characteristics of Saturated Natural Defective Material Under Different Confining Pressures

by Zhihao Gao, Shihao Guo, Xiaoyong Yang, Shanchao Hu, Junhong Huang, Yafei Cheng, Dawang Yin and Jinhao Dou

Materials 2025, 18(9), 2027; https://doi.org/10.3390/ma18092027 - 29 Apr 2025

Cited by 1 | Viewed by 948

Abstract

In nature, many brittle materials contain natural defects such as microcracks or joints, for example, rocks. Under water-saturated conditions, the strength of defective materials undergoes varying degrees of attenuation, leading to material failure and even structural instability in engineering contexts. Moreover, the deformation [...] Read more.

In nature, many brittle materials contain natural defects such as microcracks or joints, for example, rocks. Under water-saturated conditions, the strength of defective materials undergoes varying degrees of attenuation, leading to material failure and even structural instability in engineering contexts. Moreover, the deformation and failure of defective brittle materials are essentially the result of the accumulation and dissipation of energy. Studying the energy evolution of defective brittle materials under load is more conducive to reflecting the intrinsic characteristics of strength changes and overall failure of brittle materials under external loading. Natural defective brittle rock materials were firstly water saturated and triaxial compression tests were performed to determine the mechanical properties of water-saturated materials. The energy evolution patterns of water-saturated materials under varying confining pressures were also obtained. Using the discrete element method, the macro- and micro-failure characteristics of water-saturated materials were investigated, revealing the mesoscopic mechanisms of deformation and failure evolution in these materials. The results indicate that confining pressure significantly enhances the peak compressive strength and elastic modulus of water-saturated defective materials. When the confining pressure increased from 0 MPa to 20 MPa, the peak strength and elastic modulus of the water-saturated materials increased by 126.8% and 91.9%, respectively. Confining pressure restricts the radial deformation of water-saturated materials and dominates the failure mode. As confining pressure increases, the failure mode transitions from tensile splitting (at 0 MPa confining pressure) to shear failure (at confining pressures ≥ 10 MPa), with the failure plane angle gradually decreasing as confining pressure rises. Confining pressure significantly alters the energy storage–release mechanism of water-saturated defective brittle materials. At peak load, the total energy, elastic energy, and dissipated energy increased by 347%, 321%, and 1028%, respectively. The ratio of elastic energy storage to peak strain ratio shows a positive correlation, and the elastic storage ratio of water-saturated defective brittle materials under confining pressure is always higher than that without confining pressure. When the strain ratio exceeds 0.94, a negative correlation between confining pressure and the rate of elastic storage ratio is observed. From the perspective of mesoscopic fracture evolution in water-saturated defective brittle materials, the crack propagation path shifts from the periphery to the center of the material, and the fracture angle decreases linearly from 89° to 58° as confining pressure increases. The dominant direction of crack development is concentrated within the 45–135° range. The findings elucidate the mechanisms by which water saturation and confining pressure influence the strength degradation of natural defective brittle materials from both mesoscopic and energy perspectives, providing theoretical support for the stability control of related engineering structures. Full article

(This article belongs to the Special Issue Advances in Material Structural Analysis: Finite Element Analysis and Numerical Modelling)

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22 pages, 5425 KB

Open AccessArticle

Diffusion Mechanism in Running-Water and CFD-DEM Numerical Simulation of Expandable Particulate Grouting Material

by Zhipeng Zhang, Chenyang Ma, Chen Zhao, Zhuo Zheng, Wei Li, Rentai Liu, Xiuhao Li and Hongyan Wang

Materials 2025, 18(7), 1681; https://doi.org/10.3390/ma18071681 - 7 Apr 2025

Cited by 3 | Viewed by 1101

Abstract

In order to study the diffusion and sealing mechanism of an innovative grouted material tentatively called “expandable particulate grout material”, the diffusion process was simulated by the numerical method of CFD-DEM coupling. A numerical model was established for a grouting process in an [...] Read more.

In order to study the diffusion and sealing mechanism of an innovative grouted material tentatively called “expandable particulate grout material”, the diffusion process was simulated by the numerical method of CFD-DEM coupling. A numerical model was established for a grouting process in an individual fracture based on the basic physical parameters of expandable particles. The numerical model of the expandable particulate slurry flow was established. The interaction between particles and water in different conditions, such as different grouting times, different volume fractions of the particle, and different velocities, was investigated. The differences in the diffusion process and in the running-water sealing mechanism of expandable particles, cement slurry, and cement-sodium silicate slurry in the crack (in a, in b, and in c) were analyzed. The influence of expandable particles on the streamline of the grout and the drag force in the interaction process under the fracture were analyzed. This is summarized The influence of the velocity ratio of grout to water on different physical quantities, such as diffusion opening degree, diffusion velocity, and diffusion distance, was summarized. It is of significant theoretical and practical value to further develop and improve the grouting technology. Full article

(This article belongs to the Special Issue Advances in Material Structural Analysis: Finite Element Analysis and Numerical Modelling)

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