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Purpose: To measure zirconia-to-zirconia microtensile bond strength (µTBS) using composite cements with and without primer. Materials and Methods: Two Initial Zirconia UHT (GC) sticks (1.8x1.8x5.0 mm) were bonded using four cements with and without their respective manufacturer's primer/adhesive (G-CEM ONE [GOne] and G-Multi Primer, GC; Panavia V5 [Pv5]), and Panavia SA Cement Universal [PSAu], and Clearfil Ceramic Plus, Kuraray Noritake; RelyX Universal (RXu) and Scotchbond Universal Plus [SBUp], 3M Oral Care). Specimens were trimmed to an hour-glass shaped specimen whose isthmus is circular in cross-section. After 1-week water storage, the specimens were either tested immediately (1-week µTBS) or first subjected to 50,000 thermocycles (50kTC-aged µTBS). The fracture mode was categorized as either adhesive interfacial failure, cohesive failure in composite cement, or mixed failure, followed by SEM fracture analysis of selected specimens. Data were analyzed using linear mixed-effects statistics (α = 0.05; variables: composite cement, primer/adhesive application, aging). Results: The statistical analysis revealed no significant differences with aging (p = 0.3662). No significant difference in µTBS with/without primer and aging was recorded for GOne and PSAu. A significantly higher µTBS was recorded for Pv5 and RXu when applied with their respective primer/adhesive. Comparing the four composite cements when they were applied in the manner that resulted in their best performance, a significant difference in 50kTC-aged µTBS was found for PSAu compared to Pv5 and RXu. A significant decrease in µTBS upon 50kTC aging was only recorded for RXu in combination with SBUp. Conclusion: Adequate bonding to zirconia requires the functional monomer 10-MDP either contained in the composite cement, in which case a separate 10-MDP primer is no longer needed, or in the separately applied primer/adhesive. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the effect of adhesive type and long-term aging on the shear bond strength (SBS) between silicabased ceramics and composite cement (CC). Materials and Methods: Lithium-silicate (LS), feldspathic (FD) and polymer-infiltrated ceramic (PIC) blocks were sectioned (10 x 12 x 2 mm) and divided into 24 groups considering the factors: "ceramics" (LS, FD, and PIC), "adhesive" (Ctrl: without adhesive; 2SC: 2-step conventional; 3SC: 3-step conventional; 1SU: 1-step universal), and "aging" (non-aged or aged [A]). After the surface treatments, CC cylinders (n = 15, ɸ=2mm; height = 2mm) were made and half of the samples were subjected to thermocycling (10,000) and stored in water at 37°C for 18months. The samples were submitted to SBS testing (100 kgf, 1mm/min) and failure analysis. Extra samples were prepared for microscopic analysis of the adhesive interface. SBS (MPa) data was analyzed by 3-way ANOVA and Tukey's test (5%). Weibull analysis was performed on the SBS data. Results: All factors and interactions were significant for SBS (p<0.05). Before aging, there was no significant difference between the tested groups and the respective control groups. After aging, the LS_1SU (22.18±7.74) and LS_2SC (17.32±5.86) groups exhibited significantly lower SBS than did the LS_Ctrl (30.30±6.11). Only the LS_1SU group showed a significant decrease in SBS after aging vs without aging. The LS_1SU (12.20) group showed the highest Weibull modulus, which was significantly higher than LS_2SC_A (2.82) and LS_1SU_A (3.15) groups. Conclusion: No type of adhesive applied after silane benefitted the long-term adhesion of silica-based ceramics to CC in comparison to the groups without adhesive. [ABSTRACT FROM AUTHOR]

The current research introduces a novel in-situ and visibly-active heterojunction formation concept to fabricate a sustainable antimicrobial cementitious material. To achieve this, cement mortar incorporating iron-rich industrial waste products (FWPs) was outer-coated with photocatalyst Titanium dioxide (TiO 2). The proposed technique forms a novel surface-active Fe 2 TiO 5 heterojunction oxide layer, which considerably improves the photocatalytic and antimicrobial properties of TiO 2 under the visible spectrum of light. Primarily, the study evaluated the structural suitability of the developed iron-rich cementitious material in terms of its durability and strength properties. The findings indicate that the iron-rich cementitious material performed better than conventional cementitious material. After this, the effectiveness and novelty of the proposed research were examined, such that the Fe 2 TiO 5 photocomposite was subjected to detailed microscopic investigations such as XRD, HRTEM, UV-DRS, XPS, FESEM, etc. The results verified the production of the inherent Fe 2 TiO 5 heterojunction through the presence of Fe in the photocatalyst TiO 2 lattice via the formation of ITO complex bonds. It also revealed that the Fe 2 TiO 5 photocomposite functions effectively under visible light with an energy band gap of 2.57 eV. The antimicrobial activity of the Fe 2 TiO 5 photocomposite was also assessed by neutralizing E.coli bioaerosols. The disinfection results indicated that the Fe 2 TiO 5 photocomposite exhibits excellent antimicrobial properties. It achieved 69.33 % and 95–98 % antibacterial efficiency under dark and visible light, respectively. Thus, the study establishes a Fe 2 TiO 5 photocomposite material that combines photocatalytic and antimicrobial properties, making it suitable for use as a sustainable building material. Also, it contributes to environmental sustainability by promoting a circular economy and green building practices. • The design and manufacturing of an antibacterial and photocatalytic sustainable building material. • Utilization of cement mortar incorporating FWPs to make the surface active Fe 2 TiO 5 heterojunction photocomposite. • Fe from FWPs enhances TiO 2 's photocatalytic action via the inherent concept of Fe 2 TiO 5 heterojunction formation. • The Fe 2 TiO 5 photocomposite potentially inactivates E.coli bioaerosols under visible light. [ABSTRACT FROM AUTHOR]

The treatment of vertebral compression fractures of the spinal necessitates the use of injectable bone repair materials with the adaptive modulus of elasticity. Currently, newly developed injectable self-curing materials for minimally invasive surgery are primarily categorized into calcium phosphate and calcium silicate systems, both of which exhibit excellent biocompatibility. However, calcium phosphate bone cement lacks adequate mechanical properties and the stress does not match between bone and material. Calcium silicate cement has a long curing time, low mechanical strength, and high alkalinity. These deficiencies render them inadequate for meeting clinical requirements. Therefore, we incorporated inorganic disodium phosphate, organic polyvinyl alcohol, and solid component cerium oxide into the matrix phase of tricalcium silicate bone cement to establish a ternary self-curing hydration reinforcement system and produced an organic-inorganic composite injectable bone cement. Even though the composite bone cement has a longer setting time, it exhibited high compressive strength (61.9Mpa) and fracture strain (7.88 %), demonstrating excellent mechanical properties. Furthermore, it also demonstrates good injectable properties (86 %), anti-collapse properties, good biological activity, and outstanding antibacterial properties. The composite bone cement has great potential to develop a new injectable self-curing material to replace PMMA bone cement in clinical vertebral compression fractures. [ABSTRACT FROM AUTHOR]

Engineered Cementitious Composites also known as Strain‐hardening cementitious composites (SHCCs) has unique cracking patterns like cracks that have tiny widths and showcase high density. All of this makes it difficult and laborious to compute crack parameters from crack patterns. Unfortunately, this is an essential part of assessing durability and micromechanical modeling. SHSnet is developed to perform end‐to‐end semantic segmentation of SHCC cracks. SHSnet is efficient, attention based deep encoder‐decoder network with large receptive field. Loss function based on Tversky function were used for training the model. SHSnet with loss function shows promising result with mPrecision, mF1Score and mIoU of 0.87, 0.84 and 0.83 respectively for complex SHCC cracks while requiring at least an order of fewer computational parameters than those in the literature. An image processing unit is then used to estimate the width, number, and length of the cracks from the segmentation mask. Test results show that the computed crack parameters with SHSnet are exactly the same as that computed with an optical microscope but require ~100× less time. Results demonstrate that SHSnet works equally well in SHCCs with different surface textures, crack density, and widths; the final result was far superior to a conventional technique. This technique also shows promising results in an automatic evaluation of crack parameters relevant to durability and visualizing crack patterns even in the presence of artifacts during progressive testing. The results also demonstrate the necessity to accurately and densely calculate crack length and maximum crack width; else the durability results are expected to be significantly more conservative than the actual value. [ABSTRACT FROM AUTHOR]

ABSTRACT Objective Clinical Considerations Conclusion Patients who exhibit severe loss of tooth structure are challenging to rehabilitate. Conventional treatment of these patients may require adjunctive procedures of surgical crown lengthening, elective endodontic therapy and placement of posts and cores to retain full coverage crowns as part of a full mouth rehabilitation. Minimally invasive approaches to treatment of these patients provides opportunity to conserve tooth structure and to reduce adjunctive procedures by using an advanced adhesive approach to retain all ceramic partial coverage restorations as part of a full mouth rehabilitation.The use of an advanced adhesive approach to perform a full mouth reconstruction restoring occlusal vertical dimension (OVD) is described. This approach emphasizes preserving healthy tooth structure, maximizing restoration adhesion to enamel and dentin, maintaining pulpal vitality and minimizing adjunctive dental procedures. The preparation design focuses on being defect‐oriented to remove only diseased or undermined tooth structure. The all ceramic restorations are additive, where indicated, to further aid in preserving tooth structure. An advanced adhesive approach using an immediate dentin seal and resin coating over exposed dentin and composite resin cement under rubber dam isolation is used to lute the restorations. The restorations are fabricated using micro‐layered lithium disilicate ceramic to maximize the esthetic appearance of the rehabilitation where needed.An advanced adhesive approach to full mouth rehabilitation should be considered as a treatment option for patients exhibiting tooth surface loss as an alternative to conventional full coverage restorations when clinical parameters allow. [ABSTRACT FROM AUTHOR]

The mechanical performance of MoW‐HfN, a surrogate cermet for MoW‐UN Nuclear Thermal Propulsion (NTP) fuel, was characterized from room temperature to 1600°C. The modulus of elasticity and flexure strength were obtained from four‐point bend tests. Those tests revealed a loss of stiffness with increasing temperature and systematic increase in ultimate strength up to about 1400°C. This was followed by loss of ultimate strength and the onset of plastic deformation, attributed to the increased ductility of the MoW matrix above 1400°C. Chevron notch tests show that failure originates from features with a critical flaw size of ∼30 εm, which is comparable to the mean particle size of the ceramic phase. X‐ray diffraction (XRD) and Williamson–Hall (WH) analysis suggest that residual stress may contribute to the observed strength‐versus‐temperature behavior. [ABSTRACT FROM AUTHOR]

AbstractCarbon fiber-reinforced polymer (CFRP) and engineered cementitious composites (ECC) are commonly used to reinforce structural elements, with proven effectiveness in enhancing the performance of concrete-filled steel tube (CFST) columns as shown in prior experimental studies. However, the complex interaction among the components of the reinforced columns, including CFRP, ECC, the steel tube, and the concrete core, as well as the underlying mechanical mechanisms, remain insufficiently understood. This research aims to fill these gaps by developing a 3D finite element (FE) model of circular CFST short columns reinforced with CFRP grid-reinforced ECC for comprehensive numerical analysis. Sensitivity analyses are conducted to determine the governing parameters in the numerical simulation, including mesh size and critical plasticity parameters for the concrete damage model, such as the ratio of the second stress invariant on the tensile meridian to that on the compressive meridian (Kc), and the dilation angle (ψ) for both the concrete core and ECC. The model also accounts for the effects of concrete confinement provided by the CFRP grid-reinforced ECC layer and the circular steel tube. The accuracy of the FE model is validated against existing experimental data, and the model is subsequently used to investigate the behavior of reinforced CFST columns under varying geometric and material properties. The study examines failure modes, axial load-displacement responses, stress distributions, and the contribution of each material component to the load-bearing capacity of the strengthened columns. The results indicate an increase in ultimate axial strength ranging from 13% to 20% for the reinforced CFST columns. While the compressive strength of the ECC has a moderate effect on axial resistance, increasing ECC thickness, concrete strength, and steel tube yield strength significantly enhances the columns’ load-bearing capacity. Finally, a novel design model is proposed and validated, which accounts for the confinement effects provided by the CFRP grid and ECC on the concrete core. [ABSTRACT FROM AUTHOR]

This study delves into the efficacy of external strengthening methods in improving the shear behavior of defected reinforced concrete (RC) beams that lack shear stirrups, utilizing both experimental and numerical methodologies. Failure risk of such beams is a potential threat which is mitigated carefully to increase building safety and sustainability to avoid risk of construction failure. Ten RC beams underwent three-point experimental testing to assess the influence of the strengthening scheme and the presence of mechanical anchors. Two beams were designated as control specimens, while eight beams were strengthened with the application of additional strain-hardening cementitious composite (SHCC) layer in various configurations. These configurations encompassed single-sided, two-sided, and strip applications, with the inclusion of mechanical anchors. The study found that employing a single-sided SHCC, incorporating vertically bent bars into the RC beam, is recognized for its efficient alleviation of degradation in shear reinforcement. The incorporation of three SHCC strips to partially reinforce the compromised beams demonstrated a modest impact on the initial stiffness. Nevertheless, noteworthy enhancements of 46% and 42% were observed in both cracking and ultimate loads, respectively. Furthermore, increasing the number of the SHCC strips to four resulted in a more significant improvement in the load–deflection responses. Enhancing the compromised beams by applying four SHCC strips to the beams using bolts offers a feasible alternative to the configuration where SHCC was uniformly attached along the entire defected zone. Moreover, a numerical model was created to simulate the tested beams. The model effectively anticipated the progression of cracks, ultimate capacity, and deflection, indicating excellent agreement with the experimental observations. [ABSTRACT FROM AUTHOR]

The acrylic polymer composites in this study are made up of various weight ratios of cement or silica nanoparticles (1, 3, 5, and 10 wt%) using the casting method. The effects of doping ratio/type on mechanical, dielectric, thermal, and hydrophobic properties were investigated. Acrylic polymer composites containing 5 wt% cement or silica nanoparticles had the lowest abrasion wear rates and the highest shore-D hardness and impact strength. The increase in the inclusion of cement or silica nanoparticles enhanced surface roughness, water contact angle (WCA), and thermal insulation. Acrylic/cement composites demonstrated higher mechanical, electrical, and thermal insulation properties than acrylic/silica composites because of their lower particle size and their low thermal/electrical conductivity. Furthermore, to improve the surface hydrophobic characteristics of acrylic composites, the surface was treated with a dielectric barrier discharge (DBD) plasma jet. The DBD plasma jet treatment significantly enhanced the hydrophobicity of acrylic polymer composites. For example, the WCA of acrylic composites containing 5 wt% silica or cement nanoparticles increased from 35.3° to 55° and 44.7° to 73°, respectively, by plasma treatment performed at an Ar flow rate of 5 L/min and for an exposure interval of 25 s. The DBD plasma jet treatment is an excellent and inexpensive technique for improving the hydrophobic properties of acrylic polymer composites. These findings offer important perspectives on the development of materials coating for technical applications. [ABSTRACT FROM AUTHOR]

This research investigated the properties of modified cementitious composites including water purification from heavy metal—zinc. A new method for characterizing the immobilization properties of tested modifiers was established. Several additions had their properties investigated: biochar (BC), active carbon (AC), nanoparticulate silica (NS), copper slag (CS), iron slag (EAFIS), crushed hazelnut shells (CHS), and lightweight sintered fly ash aggregate (LSFAA). The impact of modifiers on the mechanical and rheological properties of cementitious composites was also studied. It was found that considered additions had a significantly different influence over the investigated properties. The addition of crushed hazelnut shells, although determined as an effective immobilization modifier, significantly deteriorated the mechanical performance of the composite as well as its rheological properties. Modification by iron slag allowed for a significant increase in immobilization properties (five-fold compared to the reference series) without a substantial impact on other properties. The negative effect on immobilization efficiency was observed for nanoparticulate silica modification due to its sealing effect on the pore network of the cement matrix. The capillary pore content in the cement matrix was identified as a parameter significantly influencing the immobilization potential of most considered modifications, except biochar and active carbon. [ABSTRACT FROM AUTHOR]

Flow production of variable curved modules for thin‐walled concrete shell structures Thin concrete shells allow to achieve considerable material savings. However, the traditional manufacturing methods, which are based on concrete casting into formwork, are uneconomical from today's perspective. The modular approach can make shell construction more cost‐effective, especially when producing shell modules with a high degree of automation. The ongoing "Adaptive Concrete Diamond Construction (ACDC) and beyond" project aims to develop an approach for fully automated fabrication of concrete shell modules of variable geometries. The project pays special attention to the reinforcement of the modules, which is accomplished by means of automatically laid carbon yarns. The contours of the modules are 3D‐printed using Strain‐Hardening Cementitious Composite (SHCC). This article presents the results already achieved in the project and also provides an overview of the ongoing work, which includes the production of non‐planar modules, the implementation of post‐processing techniques, and improving the sustainability of the new technology. [ABSTRACT FROM AUTHOR]

Current reports on accidents in urban areas reveal the devastation of boundary walls and the consequent risks to human lives and property damage. The present study proposes to mitigate such risks through the development and application of a robust and shock-absorbent composite wall system to replace the normal concrete wall system. The paper adopted a comprehensive Finite Element (FE) study using ABAQUS and used the three-dimensional validated model to initially evaluate the selected four different innovative wall systems (Polypropylene fibre-reinforced composite, ECC-Concrete, ECC-Rubberised concrete, and Rubberised concrete-Concrete composite walls) to evaluate their structural performances under lateral impact and blast loads. The most suitable composition of the wall system is identified after comparing the impact resistance, blast resistance, and the energy absorption capacity of all the selected wall structures. Then, an optimisation study on the best-performed composite is conducted to propose the most appropriate geometric parameters for the composite wall. ECC-Rubberised concrete composite wall shows the least deflection at the selected magnitudes of impact loads and blast loads compared to the other walls. The energy absorption capacity of the ECC-Rubberised concrete composite wall is the highest among all the walls including the normal concrete wall. [ABSTRACT FROM AUTHOR]

Composite concrete structures are designed to integrate various concrete types at different levels, thereby improving their shear properties. In this paper, the effects of the interfacial keyway, reinforcement ratio, and pouring sequence on the shear strength of concrete-coal gangue concrete interface are studied by experiments and analyses. A total of 10 specimens were made, and the push-off test was carried out. Nonlinear finite element simulation was carried out using ABAQUS, and the influence of keyway angle on crack development was studied based on the extended finite element method (XFEM). It is found that the remarkable tensile and crack stability of engineered cementitious composites (ECC) has a positive effect on the shear strength of the ECC-coal gangue concrete interface. The ultimate shear strength of the interface and the ductility of the interface under shear load are significantly improved by interfacial shear reinforcement. The introduction of an interfacial keyway improves the shear strength of the concrete interface, and the number of keyways has the most significant effect on the interfacial shear strength. The angle between the crack propagation direction and interface will increase with the increase of keyway angle, the simulation results are in good agreement with the experiments. [ABSTRACT FROM AUTHOR]

Recent decades have witnessed the increasing use of soil mixing technology to construct cut-off walls for groundwater control or underground pollutant containment. The strength and permeability of soil mix columns deteriorate considerably when subjected to chemical, mechanical and environmental stresses, leading to the need for repair of crack-originated damage. The development of self-healing grouts could provide more resilient and sustainable soil mix cut-off walls. In this study, for the first time, self-healing soil mix columns incorporating reactive magnesium oxide pellets were developed. The magnesium oxide-based cementitious grout was mixed with a sand soil using a laboratory-scale auger, and the embedded magnesium oxide pellets were ruptured upon cracking, producing expansive healing products due to hydration and carbonation, which can significantly fill the crack volume. The effects of magnesium oxide on the grout and soil mix samples were investigated in terms of both fresh and hardened properties. In addition, the self-healing performance was evaluated by examining permeability recovery and crack closure, and the microstructure and morphology of the magnesium oxide pellets and healing products were analysed. The results demonstrate the great potential of reactive magnesium oxide pellets as a self-healing agent for soil mix cut-off wall materials. [ABSTRACT FROM AUTHOR]

Compressive strength models for ordinary portland cement composites are typically deterministic and rely on parameters such as water-to-cement ratio, porosity, and chemical composition. While these models can estimate compressive strength, they often lack the ability to quantify uncertainty in their predictions. Various factors contribute to this uncertainty, including diverse testing protocols, limited data, overly complex mathematical formulations, and constraints in capturing the variability of the phenomenon through model parameters. This study introduces a comparative evaluation of representative compressive strength–porosity models for cement paste, adopting a probabilistic perspective and using data from various testing protocols found in the literature. Experimental data encompassing compressive strength and porosity, spanning porosity values from 1% to 30%, were gathered from hot-pressed and conventionally cast specimens. Results were obtained following the Bayesian Analysis Reporting Guidelines (BARG) with combined decision criteria using a 95% High Posterior Density (HPD) interval and the Range of Practical Equivalence (ROPE). A probabilistic version of Ryshkewitch's model emerges as the most plausible based on porosity data. These results hold promise for integration into risk analysis and decision-making tailored for structural analysis and design. Ultimately, this research contributes insights into enhancing the reliability of compressive strength predictions for cement composites by accounting for the inherent uncertainty of the underlying models. [ABSTRACT FROM AUTHOR]

Expanded polystyrene (EPS) concrete is a new typical composite concrete, but its material toughness and hydrophilicity are poor, leading to low strength and poor toughness. To solve this critical issue, this study used an interactive method of experimentation and simulation to systematically study the mechanism of how the synergistic strengthening of styrene–butadiene latex (SBL) and polyvinyl alcohol (PVA) fibers improves the performance of EPS concrete from the macro, micro, and nano multiscale systems. Macromechanical tests showed that the mechanical properties of EPS concrete are obviously improved by adding PVA and SBL. PVA fiber can reduce the compressive strength of EPS concrete but increase the flexural strength. The addition of SBL has a positive effect on the anticompression and flexural properties. Observation and analysis of microexperiments using electron microscopy, X-ray diffraction, and infrared spectroscopy showed that the addition of SBL improved the weak interface zone, increased the hydration crystallinity of unhydrated cement products, and formed a more abundant cement-based gel to fill weak cement pores, resulting in a more uniform and stable internal structure. At nano scale, the molecular dynamics interface models of EPS/calcium silicate hydrate (C-S-H), EPS/SBL/C-S-H, PVA/C-S-H, and PVA/SBL/C-S-H were established and simulated and analyzed at the nanoscale. The results showed that the addition of SBL played a crucial role in connecting organic polymers with inorganic silicates in a "bridge" form. It formed numerous hydrogen bonds and ionic bonds with EPS, PVA molecular chains, and C-S-H, effectively stabilizing the crystalline layer structure of hydrated calcium silicate and compensating for the weak hydrophilicity of EPS particles, making the EPS/C-S-H and PVA/C-S-H systems more tightly stable. Practical Applications: Expanded polystyrene (EPS) foam concrete, with its advantages of ultralightweight, easy construction, and environmental friendliness, has been widely used in the construction industry. It finds applications in load-bearing precast concrete components, thermal insulation boards, cushioning or structural insulation boards, composite floors, pavement substrates, building envelope structures, and offshore floating structures, among others. These structures possess high strength, excellent insulation performance, high fire resistance, good water repellency, affordability, and strong sound absorption and noise reduction capabilities. However, the hydrophobic nature and porosity of EPS material result in uneven stratification and segregation during the preparation of EPS particles, as well as the existence of numerous weak interface transition zones between EPS and cement-based materials. In order to further expand its prospects in engineering applications and meet the requirements of modern engineering, it is necessary to enhance the workability and mechanical performance of EPS concrete. This study combines experiments and simulations to investigate the mechanisms and methods for reinforcing EPS concrete from a multiscale and multiangle perspective, providing references for the preparation of more stable and high-performance EPS concrete. [ABSTRACT FROM AUTHOR]

Water significantly influences the electrical resistivity and piezoresistive performance of piezoresistive cementitious composites (PCCs). In existing studies, it has been difficult to reflect the actual water permeability in real structures using overall moisture content of specimens. Thus, to facilitate structural health monitoring of piezoresistive cement-based sensors in aquatic service, this study evaluated cementitious composites containing multiwalled carbon nanotubes to create a piezoresistive cement-based sensor. The variations in electrical signals were monitored to assess the internal water permeability of the specimens. An improved method for the installation of laterally arranged copper electrode meshes was developed. The changes in electrical resistivity and gauge factors before and after water permeability experiment were defined as the fractional change in permeability electrical resistivity (FCPR) and the fractional change in gauge factor (FCGF), respectively. These metrics were utilized to assess the extent of water permeability in the water-permeated specimens based on the ranges of FCPR and FCGF. The experimental results indicated that (1) with an increase in water permeability time, the moisture content and seepage height of the water-permeated specimens gradually increase, the degree of decrease in electrical resistivity becomes more pronounced, and FCR has an increasing fluctuation with periodic rises and falls under the same connection; (2) the electrical signals in the semidry region above the water mark exhibit slight fluctuations, indicating that the piezoresistive cement-based sensor can provide advanced warning of water permeability; and (3) the more extensive the water permeability, the higher are the FCPR and FCGF exhibited by the piezoresistive cement-based sensors, allowing for the assessment of water permeation. This study provides a new understanding of the unique properties and potential applications of piezoresistive cement-based sensors in aquatic environments, paving the way for their future application in monitoring and maintaining aquatic services. Practical Applications: This paper introduces a piezoresistive cement-based sensor formed by incorporating carbon nanotubes into cementitious composites. However, during service of structural health monitoring in concrete structures using piezoresistive cement-based sensors. In contrast to other studies aiming to mitigate the impact of moisture, this paper leverages the high sensitivity of the piezoresistive cement-based sensor to moisture. The water permeation in the water-permeated specimens is evaluated through changes in the electrical signals. The objective is to establish the transverse and longitudinal arrangement of piezoresistive cement-based sensors arrays in RC structures in aquatic service for water permeability monitoring and damage monitoring. As the water gradually permeates the RC structure, the piezoresistive cement-based sensors at different water permeability conditions exhibit distinct electrical signal changes. This will allow for advanced warning of steel corrosion and real-time monitoring of damage development in aquatic service for RC structures. [ABSTRACT FROM AUTHOR]

Backfilling mine goafs can significantly advance the mining industry; however, few researchers have used geopolymers reinforced with polypropylene fibers as filling materials. In this study, the flexural properties of fiber-reinforced green composite cementitious matrix–cemented tailings were examined, and the evolution mechanism of the internal structural properties of the prepared composite materials was determined. For this purpose, three-point bending tests, scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction were performed on composite samples with different blending ratios, and discrete-element numerical simulations were conducted using PFC3D particle flow simulation software. The obtained results revealed that the flexural strength and fracture properties of the studied samples increased with increasing NaOH content, decreased with increasing water-to-solid ratio, and first increased and then decreased with increasing fiber content. At a fiber content of 0.6%, the reinforcement effect reached a local optimum. The higher the NaOH content, the more efficiently fly ash and slag formed polymerization products in an alkaline environment, which contained tailing sand aggregate particles, increasing the compactness of the composite structure. The fibers in the composite material were distributed both as a single inlay and as a three-dimensional network structure to form an effective wrapping and supporting system, which further improved the flexural performance of the sample. The PFC3D simulation data were consistent with the results of three-point bending tests, illustrating the sample degradation process. The findings of this work can provide a theoretical basis for the development of fiber-reinforced green sand filling materials for mine replenishment. [ABSTRACT FROM AUTHOR]

Multiscale fiber hybridization is an essential method for enhancing and toughening cement-based materials. In this study, the influence of the content of calcium carbonate whiskers (CW) and polyvinyl alcohol (PVA) fibers on the flexural properties of cementitious composites containing 1.5% by volume steel fibers was investigated by using the hybridization of CW, PVA fibers, and steel fibers based on the four-point bending notched test. The distribution characteristics of PVA fibers and steel fibers in multiscale hybrid fiber-reinforced cementitious composites (MFRC) were analyzed and evaluated using backscattered electron imaging (BSE). The results demonstrated that the addition of an appropriate amount of CW and PVA fibers effectively improved the flexural performance of steel fiber–reinforced cementitious composites and promoted a more uniform distribution of steel fibers within the matrix. The MFRC with 1% by volume CW, 0.3% by volume PVA fiber, and 1.5% by volume steel fiber (C1P03S15) exhibited the highest flexural toughness coefficient (σb) and fiber dispersion coefficient (γ), which increased by 46.2% and 81.4%, respectively, compared to the control group without CW. Furthermore, a strong correlation between σb and γ was observed through fitting, indicating the potential for guiding practical engineering applications. [ABSTRACT FROM AUTHOR]

End-of-life tire (ELT) rubber has been widely researched to replace aggregates in construction materials such as asphalt concrete and cementitious composites. Although most studies paid attention to its effect on engineering properties and the durability of the materials, very few considered chemical reactions with pore solution and the potential for environmental leachate, especially rubberized stabilized soil, which was proposed recently to increase the use of ELT rubber in civil engineering. This study proposes the use of rubberized stabilized soil (RSS) in which clayey soils (e.g., kaolin and bentonite) were stabilized by portland cement (PC) and end-of-life tire (ELT) rubber particles. The authors previously developed a methodology to extract zinc from the ELT rubber; therefore, this study explores the potential for RSS to immobilize the leachate from the ELT rubber before and after this treatment. Three main topics are addressed in this study: (1) the capability of clay to capture leached zinc under ambient and alkaline aqueous conditions; (2) engineering properties of RSS [i.e., unconfined compressive (UCS), flow] with 0%, 10%, 30%, and 50% ELT rubber added by clay volume; and (3) pore solution and leachability tests of RSS. A leaching experiment was employed for Topic 1, UCS and flow tests were conducted for Topic 2, and pore solution extraction and leaching tests were performed for Topic 3. The results showed that the clayey soils and ELT rubber are synergistic in terms of engineering properties and the capturability of zinc and total organic carbon (TOC). Although the ELT rubber and PC strengthen the clay structure, the clay absorbs leached zinc and TOC from the ELT rubber particles. Adding untreated ELT rubber into PC-stabilized clays significantly increased the RSS strength; however, this improvement was less significant for the treated ELT rubber. Ultimately, the results proved that the environmental and mechanical performance of RSS makes it a viable construction material. [ABSTRACT FROM AUTHOR]

This study investigates crack growth and propagation in Engineered Cementitious Composite (ECC) beams reinforced with polyvinyl alcohol (PVA) fibers through numerical analysis. The research evaluates numerical findings alongside experimental data from a prior stage. Similar to the experimental phase, the numerical procedure models eight ECC beam specimens, comprising four with 2% and four with 1.5% PVA fibers, utilizing the extended finite element method (XFEM) in Abaqus software. Force-displacement and force-crack mouth opening displacement (CMOD) graphs are generated and compared with experimental results. The study demonstrates XFEM's high accuracy in numerically solving fracture problems and predicting structural behavior, as well as determining parameters assessing ECC behavior during crack growth. Findings reveal that ECC beams with 2% fibers exhibit lower loading capacity and higher displacement values, displaying greater CMOD and ductility compared to those with 1.5% fibers. Additionally, a slight impact on flexural capacity is observed with increasing PVA fiber percentages. [ABSTRACT FROM AUTHOR]

The extensive accumulation of coal-derived solid wastes in China has become a significant environmental challenge. Utilizing these wastes as resources is considered an effective approach. This study investigated activation systems for coal gangue to determine the optimal dosage for incorporation into cementitious materials. The effects of types and dosages of admixtures on the mechanical properties were examined. The results showed that augmenting the coal gangue content within a certain range enhanced the compressive strength of the composite cementitious materials. However, exceeding 20 wt.% led to a decline in compressive strength. The addition of coal gangue led to an increase in porosity. Furthermore, the addition of 4% lime and 4% gypsum resulted in enhanced properties. The performance of the resultant optimal cementitious material surpasses that of P·O 32.5 cement, making it a viable replacement in construction sector and contributing to the realization of resource recycling and ecological civilization construction goals. [ABSTRACT FROM AUTHOR]

Ferrocement is a type of thin wall‐reinforced concrete composed of hydraulic cement mortar reinforced with several layers of steel wire mesh. The material is used as a low‐cost construction and retrofit solution and allows the creation of very thin elements. In the past, the material was also used to build some structural engineering masterpieces that currently face preservation challenges. Despite the use of the material, few studies have analyzed its durability with respect to corrosion and its evaluation for preservation purposes. The paper presents the results of a testing campaign on ferrocement replica specimens subjected to a corrosive environment. After an aggressive aging procedure, where the specimens are exposed to chloride ingress, the specimens are tested through a four‐point bending test to compare their performances. Results of the mechanical behavior are compared to the results from the half‐cell potential monitoring carried out during the aging process and optical microscope acquisitions regarding the cross‐sectional corrosion‐loss area in the wires. The aim is to assess the performance of historical ferrocement exposed to degradation due to corrosion; this can be useful in identifying the best procedures to protect and preserve it, as well as in evaluating its performance over time. [ABSTRACT FROM AUTHOR]

Ductility deficiency in reinforced concrete (RC) piers is a substantial factor contributing to earthquake damage in bridge structures. In this study, the conventional concrete in the potential plastic hinge area was substituted with polypropylene fiber-reinforced engineered cementitious composite (PP-ECC), thereby leveraging its high ductility characteristics to explore the seismic performance of RC piers strengthened by PP-ECC. A finite element model was established to discuss the reinforced height, axial compression ratio, longitudinal reinforcement ratio and stirrup ratio on the hysteresis performance by referring to a published paper with a 1/5 scale test specimen. Based on the results of the parameter analysis, an ideal set of configuration parameters was proposed. Subsequently, a full-size simplified mechanical model was established with ideal reinforcement parameters. Time-history and pushover analysis were utilized to test the seismic response. The study indicates that the two analytical methods were largely consistent. The improvement in the displacement and shear force of the strengthened pier gradually decreased with the increase in acceleration amplitude. Time-history analysis reveals a decrease in the enhancement of displacement from 82.26% to 17.98% and a reduction at the bottom reaction from 12.2% to 1.5%. Under the pushover analysis method, the retrofitting level of the top displacement decreased from 77.22% to 11.53%, whereas the improvement level of the bottom shear decreased from 9.62% to 3.69%. These results provide a theoretical basis and reference standard for the application of PP-ECC. [ABSTRACT FROM AUTHOR]

The ultra‐high toughness cementitious composite (UHTCC) has the tensile strain‐hardening characteristic and an excellent ability to prevent tensile cracking. To enhance the seismic and durability performance of the conventional buckling‐restrained steel plate shear wall (BRSPSW), UHTCC‐enhanced BRSPSW (UBRSPSW) was proposed in this paper as a new type of lateral bearing system. The buckling of the inner steel plate is restrained by UHTCC‐normal concrete (NC) functionally graded panels, where the panels are composed of UHTCC and NC layers. In this study, experimental and numerical research was carried out on the UBRSPSWs. Six specimens were tested to investigate the seismic behavior of the UBRSPSW. Parameters including the number of stiffeners, the thickness of UHTCC‐NC functionally graded panels, the material of restraining panels, and the gap between the inner steel plate and restraining panels were considered in the test design. Mechanical response and failure modes of the structures under cyclic loads were analyzed. The obtained hysteretic curves and corresponding skeleton curves indicated that the proposed design had excellent seismic performance. Compared to the steel plate shear wall (SPSW), the load‐bearing capacity of UBRSPSW was improved by 13%, respectively. The appearance of macrocracks was delayed by a drift angle of 1.2%. In addition, a refined finite element (FE) model was developed and validated by the results obtained from experiments. The development and distribution of bending moments in the restraining panels were extracted based on the FE method. Then, the loading capacity design method of restraining panels and a theoretical model for controlling the crack width of restraining panels were proposed. The research results of this paper can provide useful suggestions for the seismic design of UBRSPSWs. [ABSTRACT FROM AUTHOR]

AbstractIn this work, an attempt is made to produce a ductile construction system using natural fiber-based engineered cementitious composite (ECC) beams where the conventional longitudinal steel reinforcements are replaced using glass fiber-reinforced polymer (GFRP) bars. In total, sixteen medium-scale reinforced ECC beams were tested under an un-symmetric three-point bending configuration to generate shear failure. The parameters considered as a part of the experimental program include (a) type of longitudinal reinforcement (steel or GFRP) and (b) type of natural fiber (flax, hemp, kenaf and pineapple). In addition, a detailed analytical study was performed using the Architectural Institute of Japan (AIJ) method, and a modified equation was proposed for predicting the shear behavior of FRP reinforcement using ECC beams. Test results reveal that the use of GFRP reinforcements resulted in the reduction of peak load from 33.6% to 65.4% when compared to similar steel-reinforced R-ECC beams. However, the failure mode was highly ductile due to the excellent fiber bridging mechanism, multi-crack formation and effective stress redistribution at the crack tip. The predictions obtained from the modified AIJ method improved the accuracy of shear capacity FRP-reinforced ECC sections when compared to the experiments. [ABSTRACT FROM AUTHOR]

To improve the bearing capacity and optimize the allocation of ring beam connection, a new type of steel reinforced engineered cementitious composite (ECC) ring beam connection linking the reinforced concrete (RC) beam and the concrete‐filled steel tube (CFST) column was presented. The superior tensile property of ECC can significantly solve the cracking problem that weakens the bearing capacity of the ring beam. In this paper, the failure mechanisms, contact press analysis and strain distribution of steel reinforcement for reinforced engineered cementitious composite (RECC) ring beam joints were analyzed by finite element analysis. Moreover, based on the ultimate equilibrium method, a comprehensive study was conducted on the stress transfer mechanism for the RECC ring beam joint. The bearing capacity model and simplified computational method for the beam‐to‐CFST column with RECC ring beam were proposed. Finally, the calculation method was demonstrated with experimental results. Comparison results showed good agreement, proving that the proposed bearing capacity calculation model had reliability and theoretical significance. [ABSTRACT FROM AUTHOR]

This study evaluates the structural performance of Polyvinyl Alcohol Cementitious Composites (PVCC)-layered reinforced concrete beams with coal ash under static loading. Experimental investigations included first crack load, ultimate load, load-deflection behavior, ductility, stiffness, and energy absorption. Results highlight the influence of Polyvinyl Alcohol-(PVA) fiber dosage on structural behavior. The control specimen exhibited an initial crack load of 80kN, with subsequent specimens showing varied crack initiation loads influenced by PVA fiber content. Optimal performance was observed at 1.2% PVA fiber dosage, with higher dosages leading to earlier crack initiation. Ultimate load carrying capacity increased with PVA fiber addition, reaching a peak at 1.2% dosage before slight decreases occurred with higher dosages. Load-deflection behavior demonstrated the superior performance of PVCC layered beams, particularly specimen BP3, attributed to optimal fiber content. Ductility, stiffness, and energy absorption increased with PVA fiber reinforcement, with 1.2% dosage yielding optimal results. Excessive fiber content led to diminishing returns. Energy index analysis revealed superior energy dissipation in specimens with higher PVA fiber content, emphasizing the effectiveness of fiber reinforcement in enhancing structural performance. Overall, the study underscores the importance of optimizing PVA fiber dosage to maximize structural resilience and load-bearing capacity in PVCC-layered concrete beams with coal ash. [ABSTRACT FROM AUTHOR]

Introducing supplementary cementitious materials (SCM), e.g. fly ash, into cement composite results in ecological benefits. However, in the case of high amount of SCM used as a replacement of a part of cement, there are problems related to the development of the desired properties of the final composite. Such mixtures often require activation. In the first part of this series of publications, the results of chemical activation (using Na2SO4 and Ca(OH)2) of a mixture with a very high content of fly ash were discussed. The aim of this work was to investigate the influence of mechanical activation on hydration and microstructure of the binder composed of 80% of fly ash and 20% of cement. Mechanical activation was performed using a planetary ball mill. The following instrumental methods were used to investigate the activated fly ash-cement pastes: calorimetry, TG/DTG, FTIR spectroscopy, X-ray diffraction and scanning electron microscopy (SEM) coupled with EDS. It was shown that concomitant grinding of cement and fly ash is more effective compared to separate grinding. Mechanism of hydration/activation of such mixtures was discussed in detail. [ABSTRACT FROM AUTHOR]

Steel corrosion is one of the main factors limiting the durability of existing reinforced concrete components. Based on the corrosive circumstances, different prevention and repair methods can be applied. In the case of carbonation-initiated corrosion, chemical re-alkalisation (CRA) is one of the standard measures to counteract alteration processes in the concrete that lead to reinforcement corrosion. The current state of research on the CRA of carbonated concrete and the various materials that have been investigated in terms of their applicability for this repair measure are summarised. The review summarises current research results in the field of carbonated concrete and the proven pozzolanic reactivity of the carbonation products in contact with portlandite, which suggests an inhibitory effect on CRA, although this has not yet been investigated. There are also initial attempts that deviate from the application of classic Portland cement as a repair material, but their applicability in practice must be questioned. The use of alternative binders and the associated different compositions of pore solutions and varying alkalinity of these binders (e.g. composite cements with a high substitution rate or alkali-activated binders), have not yet been investigated for repair processes such as CRA, although the chemical composition of binders is of the greatest importance for successful application of the repair measure. [ABSTRACT FROM AUTHOR]

An energy‐based isotropic elastoplastic damage model is developed for investigating the elastoplastic damage responses and stress–strain relationships of nano‐silica incorporated concrete. The formulation employs a multiscale micromechanical framework to determine the effective elastic properties of composites at different scales. The stress–strain constitutive relation is derived by splitting the strain tensor into "elastic‐damage" and "plastic‐damage" parts while introducing the homogenized free potential energy function and the undamaged potential energy function. The elastoplastic damage response of the material is further characterized by elastic–plastic‐damage coupling. To construct realistic 3D three‐phase concrete mesostructures in numerical simulations, this paper introduces an encapsulation placement method that avoids particle overlap checking when placing aggregates. This methodology allows adjustments for the aggregate compactness as needed and enhances computational efficiency in concrete mesostructure construction. The numerical results of the modeling show good agreement with the experimental values in the open literature. Further, the influence of nano‐silica addition contents and ITZ (interfacial transition zone) thicknesses on the elastoplastic damage response of nano‐silica incorporated concrete are quantitatively and qualitatively investigated for the optimization of nano‐silica incorporated cementitious composites. The proposed model facilitates simulating and optimizing the mechanical characteristics of nano‐silica incorporated concrete and enhances the computational efficiency of 3D concrete modeling with the introduced encapsulation placement method. [ABSTRACT FROM AUTHOR]

This paper introduces a novel solution for marine structures facing harsh environmental conditions—a CFRP tube‐ultralightweight cement composite (ULCC)‐stainless steel tube tubular pipe. ULCC plays a crucial role in significantly reducing the self‐weight of the pipe without compromising its mechanical performance. The study mainly focuses on investigating the bond–slip behavior between ULCC and stainless steel tube, as well as between ULCC and CFRP tube, considering a range of bond lengths, tube diameters, and tube thicknesses. To gain insight into this behavior, the distribution of strain and stress within the stainless‐steel tube and CFRP tube was effectively measured using optical fiber sensors and digital imaging correlation techniques. The findings reveal that increasing tube diameter can lead to a reduction of 69.8% and 70.3% on ultimate bond strengths for stainless steel tube and CFRP tube, respectively. Conversely, increasing the thickness of the stainless‐steel tube leads to a reduction of 56.9% in ultimate bond strength, while the bond strength between CFRP tube and ULCC benefits from CFRP tube thickness (61.0% improvement). Increasing bond length can reduce the bond strengths. Empirical equations have been provided to facilitate the calculation of average and local bond strengths based on bond length, tube diameter, and thickness. Additionally, constitutive models have been developed to accurately represent the bond–slip behavior of stainless‐steel tube‐ULCC and CFRP tube‐ULCC specimens. Understanding the bond behaviors of CFRP‐ULCC‐stainless tubular pipe allows for enhanced load transfer mechanism and composite action, and optimized structural design. [ABSTRACT FROM AUTHOR]

This paper investigates experimentally and numerically structural performance of reinforced concrete (RC) circular column under double curvature buckling moment. RC circular columns are popularity embraced in RC structures not only owing to its esthetic, attractive appearance and easy for construction, but also for its better contribution for stress resistance. However, the corner or edge columns may be exposed to edge moment (EM) transferred from beam–column joint with double curvature effect. The current investigation proposes to understand the structural exhibition of such columns subjected to double curvature buckling edge moment generated at beam–column joint considering some parameters. A total number of 11 full-scale RC circular columns were constructed, installed, and then tested up to failure studying four parameters. These parameters were: clear height-to-diameter ratio (λ), longitudinal and lateral steel ratios (μ and ρ, respectively) and concrete type. The λ ratio has been introduced with: 4.89, 4.51 and 4.14. The μ ratio has been presented by: 2.2%, 2.3%, 2.6%, and 3.1%, while the ρ ratio was employed with: 0.84%, 0.93%, 1.00% and 1.18%. Three concrete types were studied; one of them was normal concrete (NC), while the other ones were high-performance concretes (HPCs) which were engineered cementitious composite (ECC) and high-strength fiber reinforced concrete (HSFRC). Experimental outcomes revealed that all studied parameters could affect and upgrade the structural performance; however, both longitudinal reinforcement and height-to-diameter ratio provided significant enhancement (about 51%–64%). Parallel to those exploited experimentally, nonlinear three-dimensional finite element models (FEMs) were installed, executed and established considering experimental outcomes producing an acceptable model with an under/over-estimation of about 4%. [ABSTRACT FROM AUTHOR]

This paper presents the influence of supplementary cementitious materials (SCMs), such as fly ash (FA), silica fume (SF), ground granulated blast furnace slag (GGBS), and waste glass fine aggregate (GA), on the alkali-silica reaction (ASR) in high-strength and normal-strength mortar using an accelerated mortar bar test (AMBT). Residual mechanical properties and scanning electron micrographs were used to assess the changes in the matrix. GA reduced the mechanical properties of both normal-strength (NGA_OPC) and high-strength mortars (HGA_OPC), contributing to a decline in overall performance. This phenomenon was a result of the slipping of the GA from the matrix owing to its smooth surface. However, the inclusion of reactive SF and GGBS in the HGA improved the slip phenomenon of the GA, leading to a significant enhancement in its mechanical properties. Following the ASR expansion measurement, HGA_OPC demonstrated an ASR expansion rate approximately three times higher than that of NGA_OPC. This was attributed to the dense structure of HGA_OPC, which resulted in greater expansion than that of NGA_OPC. However, with the incorporation of SCMs into both HGA and NGA, a significant reduction in ASR expansion was observed. This was attributed to the delayed ASR of GA due to alkali activation or the pozzolanic reaction of the SCMs. Continuous exposure to the AMBT environment can lead to the destruction of GA. This was caused by the inner ASR that originated from the surface crack of the GA, which resulted in a reduction in the flexural strength of the mortar. The HGA with SF exhibited the highest resistance to ASR expansion and residual mechanical properties' degradation. Therefore, various durability and long-term performance-monitoring studies on ultra-high-performance concrete or high-strength cementitious composites with very high SF contents and GA can be conducted. [ABSTRACT FROM AUTHOR]

Background/Objectives: Limited research has been performed to assess the strength of resin-bonded 3D-printed restorations. Based on that, this study investigates the impact of different manufacturing methods on the fracture load of indirect composite restorations (ICRs) following an aging process. Methods: Three manufacturing techniques—conventional (CRC), milled (MRC), and printed (PRC)—were evaluated using 60 specimens, each with a diameter of 10 mm and a thickness of 1.0 mm. Sandblasting with Al2O3 particles was employed to optimize the bonding process, significantly influencing surface roughness parameters (Ra, Rz, RSm). All specimens were bonded to the dentin analog using composite resin cement and subjected to either 10,000 thermocycles (TC) or storage (ST) at 37 °C in distilled water. Fracture load assessments were performed using a universal testing machine. A finite element analysis was conducted to assess stress distribution. Results: Two-way ANOVA results indicated that the manufacturing method significantly affected mean fracture load values (p < 0.001), with PRC showing the highest mean fracture load (4185 ± 914 N), followed by MRC (2495 ± 941 N) and CRC (599 ± 292 N). The aging protocol did not have a significant impact on fracture load. Conclusions: This study revealed that 3D-printed resin composite exhibited comparable strength to milled resin composite when adhesively cemented, suggesting it is a promising option for indirect composite restorations based on its mechanical performance. However, further research is needed to evaluate its bond strength and optimal surface treatment methods to prevent early debonding. [ABSTRACT FROM AUTHOR]

The success of composite materials is attributed to the nature of bonding at the nanoscale and the resulting structure-related properties. This study reports on the interaction, electronic, and optical properties of diamond nanothread/polymers (cellulose and epoxy) and boron nitride nanotube/calcium silicate hydrate composites using density functional theory modeling. Our findings indicate that the interaction between the nanothread and polymer is due to van der Waals-type bonding. Minor modifications in the electronic structures and absorption spectra are noticed. Conversely, the boron nitride nanotube–calcium silicate hydrate composite displays an electron-shared type of interaction. The electronic structure and optical absorption spectra of the diamond nanothread and boron nitride nanotube in all configurations studied in the aforementioned composite systems are well maintained. Our findings offer an electronic-level perspective into the bonding characteristics and electronic–optical properties of diamond nanothread/polymer and boron nitride nanotube/calcium silicate hydrate composites for developing next-generation materials. [ABSTRACT FROM AUTHOR]

This study aims to investigate the effects of cement kiln dust (CKD) on the hydration reactions and mechanical properties of cement, and to evaluate its potential for use as a supplementary cementitious material (SCM). The key variables are the CKD type and the replacement ratio. Cement paste and mortar specimens containing CKD were prepared to examine their effects on the cement hydration and mechanical properties. The effect on hydration was assessed using setting time measurements, heat of hydration tests, and thermogravimetric analyses (TG). In addition, compressive strength tests were conducted to evaluate the effect of CKD on the mechanical properties of the cement. The results indicated that CKD promoted early-age cement hydration and enhanced the early-age mechanical properties. However, owing to its lack of pozzolanic reactivity, it did not significantly affect long-term hydration. Given that the effects of CKD vary slightly depending on its chemical composition, careful consideration of CKD's properties suggests that its potential use as an SCM is promising. [ABSTRACT FROM AUTHOR]

Textile-reinforced cementitious composites have great potential to offer novel design opportunities for thin-section structures thanks to their superior material capabilities. In this work, new cementitious composites with novel reinforcement configurations are developed, which have superior mechanical properties. The cementitious composites contain inclined through-the-thickness reinforcements, and their enhanced performance on thin-section material hardening under flexural loading is demonstrated. Furthermore, a new practical FE modeling approach is proposed that involves the combined use of multiple cohesive regions and 1D reinforcement elements that pass through these regions with a bilinear material law. This approach provides a new computationally efficient modelling framework whereby reinforcement pull-out during hardening is readily captured without resorting to computationally demanding interface laws between the reinforcement and the cementititous matrix. The model can model enhanced hardening of new configurations and provides comparable results with the experimental findings. The model can be used in the modelling and design of novel cementitious composites with engineered reinforcement configurations. Overall, this study aims to open up new avenues for the smart material design of cementitious composites with novel structural reinforcements. [ABSTRACT FROM AUTHOR]

Waste fiber reinforced concrete is gaining recognition as a high‐performance construction material, offering notable load‐bearing capacity, corrosion resistance, and enhanced durability features. As the building and construction industry focuses on sustainable practices, fibers derived from waste materials create an opportunity to be utilized further in composite designs. This study explores the tensile, compressive, and flexural behaviors of cardboard fibers (kraft fibers) and textile polyester fibers in concrete materials. The composite microstructure is also investigated using a scanning electron microscope (SEM) to measure the bonding performance of the fibers within the cementitious matrix. Four mix designs were created using 2.5% textile fibers as a reinforcement agent and 5% silica fume modified kraft fibers (SFKFs) as a partial cement replacement. The combination of fibers achieved 44 MPa compressive strength, equaling the control. Tensile strength was enhanced by 5% when using the combination of the two fibers, achieving 3.58 MPa in comparison to 3.41 MPa. However, flexural strength was reduced among all fibrous concrete materials. SEM images distinguished the natural and synthetic characteristics associated with the two fibers within the cementitious matrix. Namely, demonstrating the chemical bonding of SFKFs in comparison with the physical bonding properties of the textile fibers. This study serves as a valuable resource for future investigations and the broader adoption of binary waste fiber composite designs in cementitious composite applications. [ABSTRACT FROM AUTHOR]

At present, engineered cementitious composites (ECC) are rapidly replacing ordinary concrete in the building production due to its superior durability and mechanical qualities. Enormous researches have been done on ECC incorporating various fibers, industrial wastes, supplementary cementitious materials and super plasticizers. As far as fiber is concerned, poly vinyl alcohol fiber was widely explored. In this study, attempt has been made to involve alkali resistant glass fiber as a replacement for poly vinyl alcohol fiber. In addition, the high rate related with ECC as a result of the utilization of micro‐sized silica sand has restricted its extensive pertinences. Thus, this study recommends utilization of quarry dust to replace fine silica sand in the ECC at amounts ranging from 0% to 100% in order to establish a green, sustainable and cost‐effective ECC. The flowability and mechanical demeanor of the ECC mixtures in terms of the tensile, compressive and flexural properties were evaluated. It is arrived that 2% of volume fraction would be the optimum dosage by which better mechanical properties can be achieved. As a result of the present research findings, it is found that the quarry dust could be a better substitute for silica sand up to 75% without any compromise in compressive and flexural strengths. To attain higher tensile qualities, however, it might not be appropriate to replace more than 50% of the silica sand with quarry dust. Cost analysis of the ECC mixtures show that using quarry dust as aggregate is both cost‐effective and sustainable. [ABSTRACT FROM AUTHOR]

Concrete-filled tube columns may experience coupled torsion and axial compression under seismic and wind loading. Fifteen square, rectangular, and circular concrete filled steel/aluminium tube (CFST/CFAT) are tested under pure torsion to understand the behaviour and develop/validate finite element (FE) models. Parametric studies under pure torsion are conducted using FE models to study the effect of geometric (tube cross-section, length, and thickness) and tube/concrete material parameters on torsional strength, stiffness, and tube-concrete composite interaction. FE models are used to study strength, stiffness, and failure modes of CFST columns under combined torsion and axial compression load at various preload levels of axial and torsion. Coupled torsional preloading and subsequent axial load reduce the axial load capacity significantly, while coupled axial preloading and subsequent torsional loading have shown no significant influence on the torsional strength of CFST columns. Implementation of FE models developed for CFST columns with engineered cementitious composite (ECC) and carbon fibre reinforced polymer (CFRP) wraps showed significant enhancement of axial strength and stiffness compared to control (without wrap) even under high torsional preload level. The energy absorption capacity and ductility of the CFRP wrapped CFST column are about 1.38 and 1.1 times higher than its counterpart with ECC wrap of same axial load capacity. Overall, the results suggest that use of both CFRP and ECC wrap is an effective approach to enhance the torsional behaviour and ductility of CFST columns under combined torsion and axial loading conditions. However, high crack resistance and better post-peak ductility of ECC wrapped CFST compared to sudden CFRP rupture failure in CFRP-wrapped counterpart should be taken into consideration for seismic applications. [ABSTRACT FROM AUTHOR]

This research aims to study the flexural and pseudo‐ductile behavior of e‐glass biaxial and uniaxial fabric reinforced cementitious matrix (FRCM). Also, the flexural results and load–deformation curves of FRCM samples were numerically simulated using the finite element method (FEM). The experiments were started with preparation of FRCM flexural samples with different types of fabrics (biaxial and uniaxial) and their distribution in the matrix: one layer was put in the middle, two on the top, two on the bottom, and three layers were distributed equally. The surface morphology and cross‐section microstructure of the fabricated FRCM panels and cohesion of fabrics inside of them were observed using an optical microscope. Subsequently, the flexural response of the FRCM samples was measured according to standard EN 196‐1. Afterwards, based on the flexural measurements, the pseudo‐ductile behavior of the FRCM panels in terms of the ductility index (DI) was determined using energy criteria, including Naaman and Grace models. Finally, the crack propagation and flexural load‐deformation curves of FRCM samples were numerically modeled using FEM (LS‐DYNA) to validate the experiential results. The results showed that reinforcement of mortar with glass fabric leads to a significant increase in strain, especially in case of 3 layers/FRCM till 224% (uniaxial) and 110% (biaxial). Also, the uniaxial FRCM samples provided higher flexural load (3600 N) compared with mortar panel (2337 N) and biaxial FRCM (2788 N). In addition, the DI of FRCM samples was significantly improved by embedding 3 layers of uniaxial fabrics up to 152% (Naaman) and 230% (Grace), when compared with neat panel. Finally, the numerical results obtained from FEM provided a high predication to simulate the failure mode of all panels and to model the load–deformation curves with agreement >96%. Based on that, it is highly recommended to use three layers of e‐glass uniaxial fabric to reinforce the cementitious composite and to improve its flexural response. [ABSTRACT FROM AUTHOR]

To investigate the cytotoxicity on human dental pulp cells (HDPCs) and Streptococcus mutans (S.mutans) biofilm formation on universal resin composite cements (UCs). Three UCs (RelyX Universal, 3 M Oral Care - RXU; Panavia SA Cement Universal, Kuraray Noritake - PSAU; SoloCem, Coltene - SCM) and one 'gold-standard' multi-step cement (Panavia V5, Kuraray Noritake - PV5) were used following two polymerization protocols (light-cured - LC; self-cured - SC). Cytotoxicity (MTT) tests were performed after 1, 3 and 7 days of direct contact. Carboxy-2′,7′-dichlorodihydrofluorescein diacetate was used to detect the release of reactive oxygen species (ROS), and interleukin 6 (IL-6) expression was analyzed by IL-6 proquantum high sensitivity immunoassay. S. mutans biofilms were grown on UCs samples in a bioreactor for 24 h, then adherent viable biomass was assessed using MTT assay. For microbiological procedures, half of UCs samples underwent accelerated aging. Data were statistically analyzed (α = 0.05). The highest cytotoxicity was observed for PSAU SC, RXU SC, and PV5 SC at day 1, then for SC RXU after 3 days, and SC PSAU, LC PV5 and SCM after 1-week (p < 0.05). There was no increase in IL-6 expression after 1 day, while it increased depending on the group at 3 and 7 days. The highest ROS expression after 12 h was recorded for PSAU SC, PV5 SC and PV5 LC. Biofilm formation was as follows: RXU > > PSAU = PV5 > SCM, while light-curing systematically decreased biofilm formation (≈−33 %). Aging leveled out differences between UCs and between polymerization protocols. The choice of cement brand, rather than category, and polymerization protocol influence cell viability and microbiological behavior. Light-curing is beneficial for reducing the harmful pulpal effect that UCs may possess. [Display omitted] [ABSTRACT FROM AUTHOR]

The purpose of the work presented here was to examine the viability of reinforcing high-strength concrete with recycled chopped carbon fiber-reinforced polymer fibers obtained from epoxy resin-coated fiber laminated sheets. The fibers were chopped to lengths of 3 mm and 30 mm, and dosages of 0.2, 0.4, 0.6, 0.8, and 1% fiber volume fraction were tested. Compression and flexure strength tests, as well as the nondestructive tests of ultrasonic pulse velocity (UPVT) and rebound hammer, were performed on concrete samples after 28 days of curing. Carbon fiber-reinforced concrete samples were subjected to elemental analysis, mineralogical analysis, and surface morphological examination using EDX, XRD, and SEM, respectively. Using an analytical analysis method, a correlation was drawn between the mechanical properties and the various fiber lengths and doses. The experimental study found that a higher dosage and fiber content of carbon fibers improved the mechanical properties of the carbon fiber-reinforced high-strength concrete. UPVT results demonstrated unpredictability even when maintaining a fiber aspect ratio of 1:10, highlighting the need for more study in this area. [ABSTRACT FROM AUTHOR]

The construction industry has been increasingly concerned with the environment and sustainability, and one solution is engineered cementitious composites (ECC), which have self-healing, ductility, and strength properties. Researchers have been working to make ECC greener by creating synergistic mechanical interactions between fibers, matrices, and fiber–matrix interfaces. This study developed ECC using local river sand, silica fume, moderate to high-volume fly ash (FA), and bulky PVA fibers, evaluating workability and compressive strength at various testing ages (1, 7, 28, 60, and 180 days). According to the test findings, fresh ECC mortar mixtures exhibit an increase in workability with increasing FA content due to the spherical and glossy form of FA particles. All ECC samples have a compressive strength of over 20 MPa after 1 day, making them high-early compressive strength composites. The sample with the highest compressive strength after 28 days was 111.28 MPa. PVA fibers, FA, and SF contribute to increasing strength while using local river sand as an ingredient in composite mixtures is also beneficial. The samples experienced a bulging process during failure due to the use of oiled PVA fibers. The maximum load before the collapse was attained after a longer period of time where smeared cracks were visible on the samples' surface. Based on the analysis of the compressive strength over a period of more than 28 days, it is clear that both ECC mortar and bulky PVA-ECC samples exhibit sufficient strength stability. It is worth mentioning that as the curing age of ECC increases, there is a gradual increase in strength, although the level of increase is relatively slow. [ABSTRACT FROM AUTHOR]

Reinforced concrete (RC) flat-slab structures may experience progressive collapse, usually caused by the punching shear failure of slab–column joints. Existing research has shown that the use of shear reinforcements or ultra-high toughness cementitious composites (UHTCCs) in slab–column joints is efficient in improving their punching shear performance. In this study, shear reinforcement was introduced into UHTCC-enhanced RC slab–column joints. Specimens of UHTCC-enhanced slab–column joints were tested considering the effect of shear reinforcements. The cracking development process, bearing capacity and ductility were analysed. Yield line theory and critical shear crack theory were adopted to predict flexural and punching shear capacities, respectively. Finally, the failure patterns of the specimens were distinguished by comparing the predicted punching shear and flexural capacities, taking ductility coefficients into account. The theoretical and test results show the effect of shear reinforcement on the behaviour of UHTCC-enhanced joints. Significant improvements in the bearing capacity and ductility of the joints was achieved by applying shear reinforcement. The failure pattern of the joint varied from premature punching shear failure to flexural-triggered punching shear failure with the application of UHTCC, and this transformation was more pronounced with shear reinforcement applied into the UHTCC-enhanced joint. [ABSTRACT FROM AUTHOR]

This paper gives an overview of various factors that influences the performance of Limestone Calcined Clay Cement (LC3) concrete. Among the various research related to ternary cements, this paper discusses the influential factors, based on the strength and durability aspects. The factors such as the type and purity of kaolinite, limestone, gradation of the limestone, concentration of gypsum, calcined clay, limestone ratio, clinker content, water-to-binder ratio, method and effect of calcination, grinding criteria, optimum temperature of calcination, calcined clay content, method of curing and other factors are interpreted. Even low-grade materials with minimum purity have also been found to achieve the desired properties. Therefore depending upon the knowledge of the importance of every parameter, the best quality concrete could be developed with the available source and facilities. With the available quality and quantity of material, sustainable ternary cement could be obtained. By optimizing the various factors that influence the behavior of LC3 concretes, more economical and durable concrete can be produced. [ABSTRACT FROM AUTHOR]

Nanoscale graphene has demonstrated effectiveness in self-sensing cement composites and energy harvesting in buildings. However, the widespread application of graphene reinforced cement composites (GRCCs) in energy conversion is hindered by their low thermoelectric conversion efficiency. To address this limitation, multiphase cement composites with high Seebeck coefficient and low thermal conductivity are designed by using Cu2Se and ZnO. The increase in carrier mobility and enhanced phonon scattering lead to an order of magnitude improvement in the figure of merit (ZT) compared to GRCCs without incorporating Cu2Se/ZnO. A hybrid micromechanical model (HMM) based on effective medium theory and the Mori–Tanaka method is developed for predicting the electrical and thermal conductivity of the multiphase cement composites, which can be used to evaluate the thermoelectric performances of the composites. The combined experiments and modeling aim to provide guidelines for developing high-performance GRCCs with improved thermoelectric properties, potentially expanding their application in energy conversion technologies. [ABSTRACT FROM AUTHOR]

The reduction of carbon footprint, the recycling of agricultural waste, and the development of novel environmentally friendly building materials are urgent matters that necessitate innovative solutions. The objective of this study is to explore the feasibility of utilizing banana leaf ash (BLA) as a partial substitute for cement in conventional density concrete technology. The BLA-modifying additive was produced under laboratory conditions. Its chemical, phase and granulometric composition was assessed. To determine the degree of effectiveness of BLA, eight concrete compositions were developed, where the BLA content varied from 0% to 14% with an interval of 2%. The properties of fresh concrete, such as density and slump, as well as compressive strength, flexural strength, water absorption, and microstructure of hardened concrete, were studied. It has been determined that the BLA additive exhibits pozzolanic activity, with a SiO2 content of 50.83%. It is recommended that the replacement of cement with BLA does not exceed 10% for optimal results. Concrete modified with 6% BLA had the best properties and structure. The study revealed a significant 7.42% increase in compressive strength, a 7.01% increase in flexural strength, and a notable 9.28% decrease in water absorption. Thus, the obtained result proves the possibility of using BLA as a modifying additive in the technology of cement composites. The developed concrete has improved properties and is a more environmentally friendly building material than conventional concrete. [ABSTRACT FROM AUTHOR]