Search Results (405)

Calcium silicate-based cements are hydraulic biomaterials that form a calcium silicate hydrate (C-S-H) gel during hydration, a process fundamental to their setting and progressive physicochemical development. Although these materials are widely used in vital pulp therapy, evidence regarding the effects of adhesive strategy and restoration timing on bonding performance, particularly for newer premixed formulations, remains limited. This study evaluated the effects of cement type, adhesive strategy, and restoration timing on the shear bond strength (SBS) of resin composite bonded to MTA Angelus and Well-Root PT. A total of 270 specimens were distributed across two cement types, three adhesive strategies, and three restoration intervals (45 min, 24 h, and 7 days). After thermocycling, SBS and failure modes were assessed. SBS data were analyzed using three-way ANOVA, whereas failure-mode distributions were evaluated using chi-square or Fisher’s exact tests (α = 0.05). Cement type, adhesive strategy, restoration timing, and their interactions significantly influenced SBS (p < 0.001). Well-Root PT exhibited higher early bond strength than MTA Angelus. The two-step etch-and-rinse adhesive produced the highest SBS values, whereas the universal adhesive produced the lowest. Restoration after 24 h significantly increased SBS compared with restoration after 45 min, with no additional improvement observed at 7 days. Within the limitations of this in vitro study, bonding performance was influenced by cement type, adhesive strategy, and restoration timing. The time-dependent increase in SBS is consistent with continued hydration and development of the C-S-H gel-based cement matrix, although the specific microstructural changes underlying this behavior were not directly characterized. Full article

Alkali-activated mortars (AAMs) have emerged as sustainable alternatives to conventional hydraulic cement (HC) matrices produced with natural sand. In this context, interest in the valorization of industrial by-products to develop eco-efficient construction materials has gained crucial academic and industrial attention. This study investigates the feasibility of producing AAMs incorporating copper slag (CS) as an artificial fine aggregate (AFA) to partially or completely replace natural sand. Moreover, the binder matrix was formulated using 80% CS and 20% HC as precursors, activated with different alkaline solutions (Na₂SiO₃ + NaOH) at activator-to-precursor mass ratios ranging from 0.15 to 0.35. Concurrently, CS was incorporated as AFA at volumetric replacement levels of 0%, 25%, 50%, 75%, and 100%. The AAMs were evaluated in terms of workability, physical performance (i.e., bulk density, water absorption, and void content), and mechanical performance. The results demonstrate that the workability of the AAMs increased with higher AFA dosages, reaching a maximum improvement of 23.8% compared with the AAM without AFA. The bulk density of the AAMs increased monotonically with increasing AFA content (consistent with the higher density of AFA with respect to natural sand), whereas water absorption and void content decreased progressively. Although all AAMs exhibited significantly lower compressive strengths than M1 at 7 and 28 days, the differences progressively decreased with curing age. At 56 and 90 days, M5 and M6, incorporating 75% and 100% AFA, respectively, achieved mean compressive strengths that were not statistically different from those of M1, indicating that the mixtures with the highest AFA contents maintained later-age mechanical performance within the variability of the conventional reference mortar. The study demonstrates the feasibility of the synergistic utilization of CS as both precursor and AFA in AAMs. This dual-pathway valorization closes materials loops and advances circular economy principles within the construction sector. Full article

Background/Objectives: Pulp necrosis in immature permanent teeth arrests root development, leaving an open apex, thin, divergent dentinal walls, and an unfavorable crown-to-root ratio that predisposes the tooth to fracture and complicates endodontic management. An apical barrier using hydraulic calcium silicate cements has become the first-line orthograde approach for these teeth when regenerative procedures are not indicated or feasible. This narrative review synthesizes current evidence on the complete clinical pathway for apical barrier placement in immature permanent teeth, with particular emphasis on the procedural determinants of barrier formation. It also critically appraises where the evidence is robust and where it remains uncertain. Methods: The relevant English-language literature on root development, the etiology of pulp necrosis in immature teeth, diagnosis, isolation, apical barrier methods, calcium silicate materials, and treatment outcomes was reviewed through targeted searches of PubMed/MEDLINE, Scopus, Web of Science, the Cochrane Library, and Google Scholar through June 2026. The literature search was completed in June 2026; therefore, studies published after this date were not included. Evidence was narratively synthesized according to the clinical sequence of diagnosis, treatment selection, isolation, disinfection, barrier formation, restoration, follow-up, and evidence gaps. Throughout, an explicit distinction was maintained between clinical and laboratory evidence. Results: Sensibility testing is widely considered unreliable in immature teeth, complicating diagnosis. Isolation is often challenging because of traumatic crown loss. Successful treatment depends on adequate chemical disinfection, judicious minimal instrumentation, a well-condensed apical barrier of at least 4–5 mm, and a definitive coronal seal that also addresses the weak cervical dentin. Calcium silicate cements—principally MTA, Biodentine, and pre-mixed bioceramic putties—achieve high clinical success. Observational evidence further suggests, as a hypothesis requiring prospective confirmation, that material choice may be less decisive than operator experience and the quality of the coronal restoration. Conclusions: Apical barrier placement with hydraulic calcium silicate cements is a predictable orthograde preservation approach for non-vital immature permanent teeth, particularly when regenerative endodontic procedures are not indicated, not feasible, or unlikely to yield predictable clinical outcomes. Well-designed randomized clinical trials with standardized reporting are needed. Full article

As global oil and gas exploration advances into deep reservoirs, reaming-while-drilling (RWD) tools (hereinafter referred to as the reamer) are widely used to enlarge wellbores for unconventional well structures, prevent stuck pipe caused by formation shrinkage, and improve cementing quality. The flow distribution and pressure loss of reamer directly determine their operational performance, and thus, affect the success rate of reaming operations and construction quality. However, limited by intellectual property protection of core technologies and commercial barriers, no general hydraulic calculation method for reamers is publicly available. This paper presents theoretical calculations of flow distribution and pressure loss for reamers and verifies their accuracy against numerical simulations and lab tests. The results show that at a field flow rate of 40 L/s, the relative error between theoretical and experimental pressure loss is only 2.93%. Flow distribution between the bit and reamer depends solely on equivalent nozzle diameter, which dominates bottom hole assembly (BHA) pressure loss and directly governs blades pushing force. Extra flow outlets during activation cause negligible pressure loss reduction, yet pressure change at pin failure remains the key status-switching criterion. The results of this paper can serve as a theoretical reference for the research and development and field deployment of reamer. Full article

Developing low-carbon cement-based materials is a critical strategy for reducing the carbon footprint of the construction sector. This study optimized multi-component cement mortars incorporating natural zeolite (NZ), fly ash (FA), blast furnace slag (BFS), and calcium hydroxide (CH) using an L9 Taguchi orthogonal array and range analysis. Mechanical and physical properties, microstructural characteristics, statistical modeling and environmental impact were evaluated. The optimized mixture, OPT1 (10% NZ, 10% FA, 40% BFS, and 2% CH), achieved compressive strengths of 34.97 MPa and 62.67 MPa at 7 and 28 days, respectively, exceeding the control mortar by 8.4% at 28 days. The results indicated that supplementary cementitious materials (SCMs) reduced early-age strength due to the dilution effect; however, their pozzolanic and latent hydraulic reactions enhanced later-age strength development. OPT1 also demonstrated improved mechanical efficiency, reduced Global Warming Potential (GWP) by 35%, and achieved an eco-efficiency index (EEI) value of 124.6, which was 1.6 times that of the control mixture. These findings highlight the potential of the proposed system for high-performance and eco-efficient low-carbon cement mortars. Full article

Casing deformation in horizontal wells reduces the effective drift diameter of the wellbore and may interrupt workover and hydraulic fracturing operations. Accurate prediction of reshaping load is therefore important for deformed-casing repair and wellbore integrity management. In this study, the mechanical response of C110-grade elliptically deformed casing restored by a pear-shaped expander was investigated without cement-sheath constraint. Two analytical reshaping-force models based on curved beam theory and thick-walled cylinder theory were established, and a three-dimensional finite element model was developed to simulate nonlinear tool–casing contact and elastoplastic deformation. Five expander outer diameters of 122–130 mm were analyzed, and a 1:8 similarity-scaled experiment was conducted for validation. The results show that the reshaping force increased from 50.2 t to 141.7 t as the expander outer diameter increased from 122 mm to 130 mm, whereas the improvement in minor-axis expansion was relatively limited. The finite element results agreed well with the experimental results, with average errors of 8.542% for reshaping force and 8.822% for minor-axis expansion. The thick-walled cylinder model showed better prediction accuracy than the curved beam model, with an average error of 4.11%. The proposed analytical–numerical–experimental framework provides a basis for reshaping-load estimation, expander selection, and stepwise restoration process design in deformed-casing repair. Full article

To address the weak interfacial transition zone and insufficient mechanical properties of recycled aggregate pervious concrete, this study proposes a dual modification strategy using basalt fibers and ultra-fine mineral powder. The macroscopic mechanical and hydraulic properties of the material were analyzed through orthogonal experiments. Techniques including X-ray diffraction, scanning electron microscopy, and micro-computed tomography were employed to systematically reveal the microstructural evolution and internal pore network topology of the modified system. Based on range analysis of mechanical stiffness and drainage efficiency, the optimal mix proportions were determined as 5–10 mm aggregate, a water–cement ratio of 0.31, and a fiber content of 0.50%. Microscopic tests confirm that the pozzolanic reaction of ultra-fine mineral powder increases matrix density and enhances the shear bond strength between fibers and the cement paste, enabling the physical bridging effect of basalt fibers. The dual modification exhibits a synergistic effect on load-bearing capacity and crack resistance. CT scan results show that the internal pore cross-sectional area follows a unimodal skewed distribution, with the characteristic distribution peak located at 3.5 mm². This homogeneous microporous network limits the critical defect size, optimizing the stress transfer path while ensuring fluid transport. Full article

Objectives: This systematic review aimed to qualitatively synthesize the available in vitro evidence on the cytocompatibility and bioactivity of resin-modified calcium silicate ce-ments in contact with human dental stem cells and cells from other sources. Materials and Methods: An electronic search was performed in five databases. In vitro studies evalu-ating the biological properties of resin-modified calcium silicate cements were included. Cytocompatibility outcomes comprised cell viability, cytotoxicity, migration, prolifera-tion, adhesion, and apoptosis. Bioactivity outcomes comprised mineralization potential and the expression of osteo/odontogenic differentiation markers. A qualitative synthesis of the methodology and results of the selected studies was performed, together with an assessment of methodological and reporting quality using a modified CONSORT checklist for in vitro studies on dental materials. Results: Thirteen articles were included in the qualitative synthesis. Overall, the evaluated resin-modified calcium silicate cements showed reduced cytocompatibility compared with control groups, particularly regarding cell viability and migration. However, bioactivity findings were generally favorable, with several materials maintaining mineralization potential and the expression of markers associated with osteo/odontogenic differentiation. Conclusions: Resin-modified calcium silicate cements showed formulation-, concentration-, and time-dependent biological responses. Although some dual-cure materials retained mineralization potential and osteo/odontogenic activity, resin-containing formulations generally exhibited lower cytocompatibility than hydraulic calcium silicate cements. Favorable bioactivity should therefore not be interpreted as evidence of overall biological suitability, particularly when direct interaction with pulp tissue is expected. Clinical Relevance: Resin-modified calcium silicate cements should be used cautiously in vital pulp therapy, especially when direct interaction with pulp cells is expected. Full article

Cementitious sand and gravel (CSG) is commonly used in construction engineering; however, its mix proportion design is complex, and traditional physical experiments face limitations such as long cycles, high costs, and susceptibility to external factors when obtaining high-quality sample data. In this study, a foundational dataset was first acquired through physical experiments: 100 sets of CSG specimens with different mix proportions (cement content 40, 50, 60, 70 kg/m³; water-to-binder ratio 1.0, 1.2, 1.4; sand ratio 0.1, 0.2, 0.3, 0.4; fly ash content 20, 30, 40, 50 kg/m³) were prepared. After 28 days of standard curing, compressive strength and splitting tensile strength tests were conducted using a WAW-1000 electro-hydraulic servo universal testing machine, yielding 100 sets of real mechanical property data. The coefficients of variation for all test groups were below 10%, confirming the reliability and repeatability of the experimental data. On this basis, a data augmentation method based on Conditional Tabular Generative Adversarial Networks (CTGAN) is proposed. Through adversarial training between the generator and the discriminator, the model learns the multi-dimensional distribution characteristics of the original CSG data and generates 100 synthetic samples, which are then merged with the original data to expand the dataset to 200 samples. The quality of the synthetic data is evaluated using Wasserstein distance and correlation matrix heatmaps. Furthermore, a hybrid XGBoost–LSTM prediction model is proposed—XGBoost is used for feature construction to capture nonlinear interactions among mix proportion variables, and the constructed features are then fed into an LSTM network for sequential learning and regression prediction. The results show that the CTGAN-generated data are highly consistent with the original data in terms of kernel density distributions and variable correlations, with Wasserstein distance significantly superior to four comparative methods: Bootstrap, SMOTE, GaussianCopula, and TVAE. After augmentation, the XGBoost–LSTM model achieves a coefficient of determination (R²) of 0.9897 for compressive strength prediction (vs. 0.9793 before augmentation) and 0.9801 for splitting tensile strength (vs. 0.9882 before augmentation, a slight decrease). The mean absolute percentage errors (MAPE) are 4.49% and 4.11%, and the root mean square errors (RMSE) are 0.201 and 0.049, respectively; both error metrics are reduced compared with those before augmentation. Compared with baseline models including XGBoost, LSTM, Random Forest (RF), and Support Vector Regression (SVR), the XGBoost–LSTM model exhibits the best performance across all evaluation metrics, and Wilcoxon signed-rank tests confirm that the performance differences are statistically significant (p < 0.05). The proposed method of CTGAN-based data augmentation combined with the XGBoost-LSTM hybrid model provides an effective solution to the problem of insufficient CSG sample data and offers a reference for data enhancement and performance prediction of other small-sample materials. Full article

Wellbore fluid flow and heat transfer are strongly coupled during drilling and well construction, where temperature, pressure, rheology, gas behavior, transient operations, and cementing displacement jointly affect pressure-window control and wellbore safety. This review synthesizes advances in coupled wellbore thermal–hydraulic numerical simulation, emphasizing governing equations, discretization strategies, coupling algorithms, rheology and turbulence closures, verification and validation, computational efficiency, uncertainty quantification, and AI-assisted deployment. A bibliometric-guided critical review was conducted using an 841-record Web of Science corpus, 79 screened technical records, 86 screened OnePetro field-facing records, and representative prior reviews. CiteSpace was used to identify knowledge structure and thematic evolution, while screened records were coded by governing physics, numerical method, closure assumption, model output, validation evidence, and deployment relevance. The literature is organized into five model families: wellbore temperature and heat transfer; annular non-Newtonian flow, rheology, turbulence, and CFD; pressure-window and transient hydraulics; cementing displacement and well-construction flow; and AI-assisted calibration and deployment. The synthesis shows that field-deployable simulation requires consistent state variables, transparent closure hierarchies, benchmark validation, uncertainty reporting, CFD-to-well-scale transfer, reduced-order implementation, and physics-constrained AI updating. Full article

To reveal the influence of water accumulation in open pits on the stability of boundary coal–rock pillars, this study investigates a boundary coal–rock pillar between an underground coal mine and an adjacent open pit in western China. Coal–rock physical property tests, hydrochemical analysis, permeability tests, and theoretical calculations of water-resisting coal–rock pillars were conducted to examine seepage channel formation, physical property changes, and stability evolution under long-term water accumulation. The results show that the mechanical strength of coal and rock specimens decreases under the saturated state. The uniaxial compressive strength of rock specimens decreases by 8.75–50.64%, while that of No.2⁻² and No.3⁻¹ coal specimens decreases by 17.72% and 25.01%, respectively. The tensile strength decreases by 24.59–59.11%, and the shear strength decreases by 4.36–45.96%. The hydraulic conductivity of intact specimens is mostly 10⁻⁴~10⁻³ m/d, whereas that of fractured specimens increases to 10⁻³~10⁻² m/d. The calculated width of water-resisting coal pillars increases by 19.7~21.9% under long-term water accumulation. Long-term water accumulation in the open pit changes the external hydraulic boundary of the boundary coal–rock pillar, allowing water to migrate inward along bedding planes, joints, primary fractures, mining-induced fractures, and coal seam pores. This process promotes the connection of pre-existing pore–fracture structures and seepage channel formation, weakens particle cementation and structural-plane shear resistance, and reduces the structural integrity, bearing capacity, and water-resisting capacity of the coal–rock pillar. Therefore, the stability deterioration of boundary coal–rock pillars is a continuous process involving channel formation, sustained seepage, strength degradation, enhanced pore–fracture connectivity, permeability enhancement, and further stability reduction. Full article

The degradation of the natural fibers in the hydraulic binder alkaline matrix is widely known. This study investigates the effect of two fiber treatments, namely immersion in sodium hydroxide (NaOH) solution and hornification, in two types of alkaline environmental ordinary Portland cement (OPC) and a mixture of OPC and natural hydraulic lime (NHL). After curing for 28 days, the specimens were subjected to 25 and 50 dry–wet aging cycles to evaluate their degradation behavior. Subsequently, the specimens underwent flexural and compressive strength tests. This study reveals that the specimens with the mixed binder of ordinary Portland cement (OPC) and natural hydraulic lime (NHL), after 50 aging cycles, reached toughness values in the descending branch compared to the total toughness obtained in the flexural–displacement diagram, of 17% and 27% for the treatment with NaOH and hornification fiber, compared to 3% and 10% obtained for the matrix with an OPC binder. Therefore, the inclusion of NHL as a matrix binder provided better softening behavior than those with only the OPC binder, providing better protection of the fibers against environmental alkalinity due to matrix alkalinity. In addition, the hornification treatment better preserved the fibers throughout the aging process. Full article

As an innovative ecological material widely adopted for surface protection of hydraulic soil–cement slope composites, 3D ecological slope protection mats remain insufficiently studied in terms of their anti-scour capacity under hydrodynamic erosion. This work combines physical model tests and numerical simulations to investigate its scour resistance, and adopts a radial basis function (RBF) neural network-based intelligent inversion method to calibrate numerical model parameters. Physical test results demonstrate that longer vegetation growing periods effectively strengthen slope anti-scouring performance. At 2 m/s flow velocity, extending the growth period from 2 months to 3 and 4 months increases bed shear stress of 3D ecological protection mat specimens by 41% and 19%, reduces soil loss by 49% and 33%, and decreases scour depth by 23% and 13%. Both scour depth and soil loss rise rapidly initially before leveling off, with larger ultimate values under higher flow velocities. The established numerical model achieves a 3.1% relative error between inverted and measured data, proving high inversion accuracy. Simulations under 1~5 m/s flow velocities reveal that flow velocity decreases significantly over the protected slope, and scour depth and scouring area expand gradually with increasing flow velocity. Full article

A novel alumina-filled ceramic-reinforced polymer (CRP) crown (Hassawat-01; HS) was developed. This study evaluated the effect of luting cement on the marginal and internal adaptation of HS and compared its performance with a commercial DLP-printed CRP (VarseoSmile Crown Plus^®; VS) and a milled resin nanoceramic (Cerasmart^® 270; CE). Ninety-nine crowns (n = 33/material) were fabricated with a 50 µm cement space and luted using Maxcem Elite^®, RelyX Unicem^®, or Ketac Cem^® (n = 11/subgroup). Adaptation was assessed without and with cementation using micro-computed tomography at 160 measurement points per crown. Without cementation, HS demonstrated the most favorable internal adaptation, whereas VS showed the best marginal adaptation. Following cementation, gap dimensions increased in all groups. Despite its superior non-cementation fit, HS exhibited the greatest increase in marginal and internal discrepancies, suggesting increased hydraulic resistance during seating. Among the evaluated cement–crown combinations, VS luted with RelyX Unicem^® showed the most favorable post-cementation adaptation. Post-cementation analysis was limited to HS and VS because the radiopacity of CE prevented reliable cement interface segmentation. These findings indicate that adaptation is influenced by both crown geometry and cement properties, and that highly adapted intaglio surfaces may require careful cement selection to optimize clinical fit. Full article

Clay–cement slurry, as a widely used anti-seepage material, is prone to calcium leaching and deterioration when exposed to environmental water. The influence of microstructural and mineralogical evolution on the transport properties of clay–cement samples under leaching conditions remains to be investigated. In this paper, accelerated calcium leaching tests were conducted on clay–cement pastes. A variety of techniques, including XRD, SEM, and NMR, were used to characterize the microstructural and mineralogical changes in the leached samples. The effect of accelerated leaching on transport behavior was studied by measuring changes in the water permeability and calculating diffusivity. XRD and SEM analyses show that after 28 days, the characteristic peaks of portlandite and ettringite almost disappear, while C-S-H gel undergoes decalcification and decomposition, leading to an increase in pore number and a notable rise in pore size (up to 1.90 μm). NMR results indicate that total porosity and peak pore size increase significantly, with the proportion of gel pores decreasing and that of small capillary pores (10–50 nm) rising from 10% to 22.1%. Moreover, the surface layer porosity (0–5 mm) increases from 31.33% to 50.65%, while the middle and lower layers show less degradation, indicating a progressive deterioration pattern. Regarding transport properties, the hydraulic conductivity increases from 4.7 × 10⁻¹⁰ cm/s to 2.14 × 10⁻⁸ cm/s (a two-order-of-magnitude increase), and the diffusion coefficient rises from 1.6 × 10⁻¹¹ m²/s to 8.6 × 10⁻¹¹ m²/s (a 5.3-fold increase). Both the diffusion coefficient and its increase factor gradually decrease from the surface to the interior, consistent with the evolution of porosity. Full article