Search Results (2,408)

Objectives: This systematic review evaluated the clinical performance and survival of adhesive attachments used as retention elements for removable partial dentures (RPDs) and analyzed associated biological and technical complications. Methods: A systematic electronic search was conducted in PubMed, the Cochrane Library, and Embase in August 2025. Eligible studies included randomized controlled trials, prospective or retrospective clinical studies, and case series with at least 10 patients and a minimum 6-month follow-up. The primary outcome was attachment survival; secondary outcomes included biological and technical complications. Two reviewers independently performed screening, data extraction, and risk of bias assessment using the Newcastle–Ottawa Scale. Due to high heterogeneity, results were analyzed descriptively. This review was prospectively registered (PROSPERO registration number CRD420251116027) and conducted in accordance with PRISMA guidelines. Results: Of 5514 records identified, five longitudinal clinical studies fulfilled the inclusion criteria. Sample sizes ranged from 10 to 123 patients, with follow-up periods between 3 and 270 months. Reported attachment survival ranged from 96% at one year to 61% at 15 years. Technical complications, mainly debonding, occurred in 9% to 18.5% of cases, while biological complications such as caries or abutment fractures were infrequent. All studies were rated as poor-quality owing to missing control groups and incomplete outcome reporting. Conclusions: Within the limitations of the available evidence, adhesive attachments represent a potential option as an invisible retention element for removable prostheses. However, the available findings are based on a limited number of studies with methodological limitations and therefore represent low-certainty evidence. While some studies suggest favorable short-term performance, long-term survival appears to be limited. Debonding was the most frequently reported technical complication, highlighting the technique sensitivity of adhesive cementation. Further well-designed comparative clinical studies with larger sample sizes are required to better clarify their long-term efficacy and clinical indications within removable prosthodontics. Full article

Geopolymer materials obtained through the alkaline activation of fly ash represent a promising alternative for reducing the environmental impact of the construction sector, which is currently dominated by cement use. This study aimed to develop self-cleaning geopolymer composites by incorporating TiO₂ nanoparticles. Specimens containing 1%, 3%, and 4% TiO₂ were prepared using alkaline solutions based on Na₂SiO₃ and NaOH (6 M or 8 M), at mass ratios of 1:1 and 2:1. The results indicate that the three analyzed factors—the NaOH solution concentration, the activator ratio, and the nanoparticle dosage—significantly influence density, mechanical strength, and water absorption. Increasing the NaOH concentration to 8 M led to slight densification, improved flexural and compressive strength, and reduced water absorption. Modifying the Na₂SiO₃:NaOH ratio produced similar densification effects but resulted in reductions in mechanical strengths. The addition of 1–3% TiO₂ increased density and mechanical performance while reducing water absorption, whereas 4% TiO₂ content had the opposite effect. Self-cleaning capacity was confirmed by up to ~90% degradation of Rhodamine B after five UV–artificial rain–drying cycles, compared to only 27.3% degradation for the control samples. Full article

This study aims to systematically synthesize and critically evaluate the characteristics of electric arc furnace slag (EAFS) and ladle furnace slag (LFS) when applied as an alternative paving material. A systematic literature review was conducted following the PRISMA methodology, with research published between 2000 and 2024. Three major databases were searched, considering only Q1–Q2 and English articles. After independent, blinded screening by two reviewers, a total of 177 papers met the selection criteria. The results were qualitatively synthesized through bibliometric analysis, slag characteristics, and application type. Results show that asphalt concrete (AC) is the most common application of EAFS, representing 61% of studies, with many studies exploring 100% substitution of natural aggregates. Overall, EAFS and LFS demonstrate favorable mechanical properties, including high toughness, hardness, and adequate soundness, largely attributed to their iron-rich composition, supporting their use in base layers, AC, and Portland cement concrete (PCC). However, significant chemical and mineralogical variability influences swelling potential and reactivity, highlighting the need for case-specific characterization. While swelling concerns limit its use as an unbound base material, these issues are reduced when EAFS and LFS are used as a soil binder or encapsulated within AC or PCC matrices. Environmental assessments show that most EAFS and LFS samples meet the regulatory thresholds for their respective local leaching limits, though behavior varies with steel type (low-alloy vs. stainless), particle size and pH. Significant gaps remain in long-term performance and testing standards. This review proposes guidelines for selecting appropriate tests according to the intended pavement application, aiming to facilitate the safe and effective use of EAFS and LFS in road infrastructure. Full article

To investigate the mechanical bearing characteristics of the “excavation-backfill” composite after the excavation of coal pillars and backfill replacement with gangue-based cemented paste backfill, mechanical bearing characteristic experiments are conducted on a series of coal samples with rectangular “excavation-backfill” roadways under uniaxial loading, covering the full deformation and failure process. The MTS universal testing machine and DS5-type acoustic emission signal acquisition system are employed, and a high-speed camera is adopted to monitor and record the full failure process. The mechanical bearing characteristics and crack evolution mechanisms of unfilled coal pillar (U-C) and backfill coal pillar (B-C) samples are explored. The results show that with the increase in “excavation-backfill” width, the uniaxial compressive strength and elastic modulus of U-C samples decrease significantly, and the samples exhibit brittle–ductile failure. When the “excavation-backfill” width is 60 mm, the backfill can distinctly improve the strength and elastic modulus of B-C samples, showing a strong strength recovery effect. The temporal characteristics of AE signals indicate that both U-C and B-C samples experience four stages subjected to uniaxial compression: quiet period, rising period, active period, and post-peak rising period. In the quiet period and rising period, the b-value fluctuates upward with energy release; in the active period, the b-value decreases significantly with large energy release; in the post-peak rising period, crack propagation and frictional slip increase, leading to an enlarged fluctuation amplitude of the b-value. Based on the location of AE sources, the three-dimensional crack chain evolution is inverted. The crack chain evolution of the U-C is mainly distributed along the dip direction (75°~90°, 255°~270°) and vertical direction (165°~180°) of the coal bedding plane, while the B-C is more uniform, indicating that the backfill evidently affects the crack distribution. This study provides new insights for predicting the crack evolution and failure mode of coal–rock composites. Full article

The cement industry seeks alternative raw materials to lower its environmental impact, and biomass ash represents a potential material for construction applications. This study evaluates biomass ashes (BMA) produced from grate and fluidized bed combustion, as well as co-combustion with coal, focusing on their chemical, mineralogical, and physical characteristics. The results reveal a substantial variability in BMA composition, influenced primarily by the fuel type and combustion method. This heterogeneity critically affects the reactivity and overall suitability of the BMA for use in construction materials. It was found that none of the 23 analyzed samples met the requirements of EN 450-1. This outcome is largely attributable to the combustion process and to sampling from the bottom part of the boiler, which typically yields material with properties outside the limits of the standard. Even when assessed directly against the specific limit values of EN 450-1, the ashes did not comply without further processing or modification. Despite these limitations, BMA show potential for use in accordance with EN 197-1, which permits the incorporation of up to 5 wt.% minor additional constituents. However, their practical application under this framework requires validation through tests performed on hydrated cement. These findings underline both the limitations and the promise of BMA as a supplementary cementitious material (SCMs) in sustainable construction. Full article

Despite extensive pore-scale studies on oil–water displacement, quantitative understanding of the dynamic evolution of residual oil morphology and waterflooding efficiency in geologically heterogeneous sandstones remains limited, particularly under large water-injection multiples. To better understand pore-scale oil–water distribution and its influence on enhanced oil recovery, this study utilized Micro-CT combined with SEM-EDS to examine the 3D pore structure and oil–water phase evolution in a heterogeneous sandstone sample from the Xiayang Formation, Wushi Sag, Zhanjiang. Mineralogical analyses reveal that dolomite cementation and vermicular kaolinite infilling introduce strong pore-scale heterogeneity by selectively reducing pore connectivity and permeability, posing challenges for uniform fluid displacement. A 30% KI solution was used to enhance X-ray attenuation of the aqueous phase, enabling clear discrimination between oil and water. Micro-CT reconstructions reveal a relatively uniform pore network dominated by medium-to-large intergranular pores. As the water-injection multiple increases, water progressively invades larger pores, while residual oil is immobilized by capillary forces within micro-throats, forming isolated clusters. The oil-droplet size distribution broadens from a narrow range (50–100 µm) to a wider one (200–300 µm), indicating interfacial destabilization and droplet coalescence. Quantitative analysis indicates that oil saturation decreases from approximately 90% to 36%, while waterflooding efficiency increases rapidly to ~45% at 1 PV and gradually approaches a plateau of ~60% beyond 500–1000 PV. This waterflooding plateau is attributed to capillary trapping and pore-scale connectivity limitations imposed by mineral-induced heterogeneity, which prevent further mobilization of residual oil despite continued water injection. This study advances pore-scale waterflooding research by combining mineralogical heterogeneity with long-term micro-CT imaging, revealing the pore-scale mechanisms controlling residual oil evolution and ultimate waterflooding limits in realistic sandstone. Full article

This paper presents the results of a laboratory-based treatability study conducted for a confidential former wood treating site heavily impacted by a creosote non-aqueous-phase liquid (NAPL) containing pentachlorophenol (PCP). PCP impacts in the silty sands extended to approximately 33 ft (10 m) below the ground surface (bgs), with discrete soil samples containing PCP concentrations up to 14,500 mg/kg, and groundwater PCP concentrations forming a main plume exceeding 1 mg/L over 2.16 acres (0.87 ha). Treatability testing was performed on unspiked and NAPL-spiked site soils with total PCP concentrations ranging from 10 to 100 mg/kg, respectively, and leachable PCP concentrations of approximately 3 to 8 mg/L. Stabilization/solidification (S/S) mix designs using 5 to 10 weight percent (wt%, dry-reagent-to-wet-soil mass basis) of a Portland cement (PC) blend and 1 wt% powdered bentonite met the minimum unconfined compressive strength (UCS) and maximum hydraulic conductivity (K) performance criteria of 50 lb/in2 (345 kPa) and 1 × 10⁻⁶ cm/s, respectively, within the specified 28-day cure time. Long-term semi-dynamic leach testing was performed on S/S-treated soils using a modified United States Environmental Protection Agency (EPA) Method 1315 test incorporating a polydimethylsiloxane (PDMS) liner to improve the data reliability for hydrocarbons. Results showed that adding 1 wt% organoclay (OC) to the S/S mix designs did not substantially reduce leaching of common semi-volatile organic compounds (SVOCs) such as naphthalene, acenaphthene, phenanthrene and benzo(a)anthracene compared to mixes using only the PC blend with bentonite, consistent with previous studies. However, the inclusion of OC had a decisive effect on PCP immobilization, providing an order-of-magnitude (10×) reduction in the cumulative mass release of PCP over the test duration. This benefit diminished with decreasing degree of chlorination for other phenolic compounds. Full article

This study’s primary objective is to determine how boron-containing wastes from the stripping areas of the Emet–Bigadiç (Türkiye) boron deposits affect the mechanical performance of cement-based mortars and the effectiveness of weak soil improvement. The Bigadiç samples contain colemanite, calcite, dolomite, and quartz minerals, whereas the Emet samples predominantly comprise calcite. The wastes were incorporated into the cement matrix in two different forms: (i) solid-phase cement replacement and (ii) boron waste solution additive. Experimental findings demonstrated that replacing 10% of cement with a 4% Bigadiç-origin boron waste solution resulted in a compressive strength of 55.37 MPa after 7 days of curing, which is higher than that of the reference mixture. Also, the study revealed that the addition of 15% boron waste to weak soils increased the soil density to 1728 kg/m³ by filling micro-voids and enhancing intergranular interlocking. Due to this physical filling and chemical bridging effect, CBR value increased from an initial 4 to 6, providing a significant improvement in the soil’s deformation modulus and bearing capacity. Consequently, used boron wastes not only provide high mechanical performance in cement-based systems but also offer potential as an alternative additive material for sustainable and cost-effective soil stabilization applications. Full article

Accurate determination of the physico-mechanical parameters of rock and soil masses is fundamental to the quantitative stability analysis and engineering mitigation of open-pit mine slopes. However, existing studies often rely on generalized parameters and lack systematic empirical data based on full-hole in situ core sampling to quantitatively verify the link between microscopic mineralogy and macroscopic instability. To address this gap, this study investigates the mineral composition, microstructure, and hydro-mechanical behavior of geotechnical materials, using the XG Open-pit Coal Mine in Inner Mongolia as a case study. Field drilling and sampling with a cumulative depth of 1500.7 m were conducted, combined with systematic laboratory tests. The results reveal significant lithological heterogeneity within the mining area. Specifically, hard rocks (e.g., fine sandstone) constitute the stable framework of the slope, whereas mudstones rich in hydrophilic clay minerals, along with low-strength coal seams, form potential weak sliding interfaces. Quantitative X-ray Diffraction (XRD) analysis reveals that the weak mudstone layers contain up to 32.4% hydrophilic expansive minerals (montmorillonite and illite/smectite). Scanning Electron Microscopy (SEM) and slake durability tests demonstrate that the mudstone is characterized by well-developed micropores (1–2 μm) and loose cementation. Theoretical analysis indicates that upon saturation, the strength of these weak layers is reduced by over 40%, causing the factor of safety (FoS) to drop from a stable 1.48 to a critical 0.89. Based on these findings, the slope instability mechanism driven by “Stiffness Mismatch and Hydro-Weakening” is elucidated. Consequently, targeted reinforcement and drainage measures are proposed to provide a scientific basis for safe mining operations. Full article

This study investigated the potential use of ash derived from Municipal Solid Waste (MSW), typically destined for landfill in Israel, as a partial replacement for cement and aggregates in concrete mixtures, aligning with circular economy and sustainable construction objectives. MSW samples (post-metal and large plastic remains removal), supplied by the Dudaim Reclamation Center in Israel, were incinerated under controlled conditions in an upgraded laboratory furnace to produce ash. The ash content in the Israeli MSW was 18% ash. The ash consisted mainly of calcium-based minerals, including anhydrite (CaSO₄), alite (3CaO·SiO₂), and calcite (CaCO₃), with minor quartz content, indicating potential pozzolanic behavior. The characterization results showed that appreciable amounts of ash produced from MSW incineration in Israel can be used as a partial replacement for cement and fine aggregates when properly treated. This study successfully established a laboratory-scale incineration process for Israeli MSW. The resulting ash was characterized, confirming its potential as a raw material for concrete applications, thereby paving the way for future studies on its performance as a partial substitute for cement and fine aggregates in concrete blends. Full article

The construction sector is currently tasked with the critical challenge of minimizing CO₂ emissions associated with cement manufacturing. To support a sustainable building environment, this research developed cement-free alkali-activated composites by leveraging industrial by-products, specifically fly ash and blast furnace slag. The study experimentally evaluated how aluminosilicate material-based capsules (AMCs) composed of a mixture of fly ash, blast furnace slag, and ferronickel slag powder affect the composites’ durability, mechanical properties, and self-healing capabilities, alongside microstructural investigations. Results indicated that specimens incorporating 10% AMC reached a compressive-strength recovery range of 112–118%, which represents an improvement of approximately 10% compared to the control sample. Furthermore, the 28-day resistance to chloride ion penetration was enhanced by 79.4%, successfully meeting the ‘very low’ permeability criteria defined by ASTM C 1202. These results suggest that cement-free self-healing composites incorporating AMCs are a viable alternative for reducing carbon emissions and minimizing environmental impact in the construction industry. Furthermore, the recycling of industrial byproducts, as demonstrated herein, contributes to sustainable development in response to climate change. Full article

Natural gas hydrate (NGH) deposits represent a vast and clean energy source. However, sustainable gas production from these resources remains an unsolved technical problem due to potential geohazards and climate challenges. A critical issue in this regard is the difficulty of obtaining in situ samples, which are essential for detailed laboratory studies of NGH’s geomechanical and chemical behavior for safe and green gas production after hydrate dissociation. Currently, the retrieval of representative samples from NGH reservoirs is hindered by significant technological limitations and high costs. Consequently, laboratory-synthesized gas hydrate-bearing sediment (HBS) samples are crucial for controlled research purposes and validating numerical simulation models and are used in the majority of research studies. With this in mind and considering the complexity of synthesizing HBS samples, this study comprehensively reviews different methods of synthesizing gas hydrates in porous media, including excess-gas, excess-water, dissolved-gas, spray, bubble injection, and hybrid techniques. Each method produces distinct hydrate morphologies (e.g., pore-filling, cementing, grain-coating, etc.) and saturation levels, with trade-offs in speed, uniformity, reproducibility, and ease of control. Furthermore, the current review details the synergic application of non-invasive characterization techniques, i.e., X-ray Computed Tomography (CT) and Nuclear Magnetic Resonance (NMR), in studying gas hydrates. CT provides high-resolution three-dimensional (3D) structural images of pore geometry and hydrate distribution, while NMR/MRI (Magnetic Resonance Imaging) quantifies fluid saturations and tracks hydrate formation/dissociation dynamics in real time. The synergistic use of CT and NMR offers a powerful multimodal approach, overcoming individual limitations such as CT’s poor hydrate–water contrast detection and NMR’s indirect hydrate inference, which could help in the sustainable synthesis of particular hydrate morphologies. Finally, the critical analysis of current technological challenges or gaps and also the emerging trends and future directions in the study of HBS, including advanced imaging techniques, AI-assisted analysis, and standardization efforts, etc., are discussed. It was found that the selection of the most appropriate method for natural gas hydrate synthesis is mostly task-specific, and the emerging technologies have facilitated the synthesis of HBS samples with more precise control of morphology, saturation, etc. This review provides the required insights for sustainable synthesis and characterization of hydrate-bearing sediments samples and serves sustainable gas production from natural gas hydrate reservoirs. Full article

During the extraction of shale oil from the Longmaxi Formation in the Sichuan Basin, it is found that the core samples contain natural fractures cemented by various minerals. However, the core extraction process is complex and expensive. In order to further investigate how cracks propagate and initiate in samples containing cementing layers under compression conditions, this study developed an experimental method involving plug cutting and mineral cementation reconstruction for the preparation of representative semi-artificial core samples. Through comprehensive analysis using computed tomography (CT), stereomicroscopy, and mechanical testing, we have demonstrated a high degree of consistency between artificial cemented cracks and natural cemented cracks. Through triaxial compression and Brazilian splitting experiments on artificially cemented samples, we found that low and high confining pressures significantly affect crack morphology. By using Abaqus finite element simulation to add crack propagation modes during the compression process of cement layers, we showed that different mineral cements (quartz, clay, and calcite) have secondary effects on crack morphology on the basis of confining pressure. Full article

High-chromium cast iron is widely used in cement, mining and metallurgy, but its as-cast state has defects such as coarse carbides, uneven distribution and severe elemental segregation, resulting in insufficient toughness and poor wear stability. Taking Cr20 type high-chromium cast iron as the research object, two sample groups (without/with La) were designed. XRD, OM, SEM, EDS, mechanical property tests and impact wear experiments were used to study the effects of La addition and different quenching temperatures (900 °C, 950 °C, 1000 °C, 1050 °C) on its properties. The results show that La does not change the phase composition but refines carbides, alleviates segregation and promotes secondary carbide precipitation. Suitable heat treatment enhances properties, while excessive temperature (1050 °C) causes performance degradation. Sample 2 (with La, quenched at 1000 °C) has the optimal comprehensive properties, with superior hardness, impact energy and wear resistance. This study provides an experimental basis and technical reference for optimizing high-chromium cast iron properties. Full article

Concrete remains one of the most widely utilized construction materials, valued particularly for its exceptional compressive strength. However, exposure to fire can compromise both its internal microstructure and external integrity. This research investigates the behavior of concrete manufactured with recycled concrete coarse aggregate (RCA) derived from construction waste, aiming to establish experimental evidence of fire’s impact on compressive strength. We employed the Optimal Density Method to design mix proportions targeting 24 MPa compressive strength. The experimental program comprised 45 cylindrical samples distributed across three replacement levels: 0%, 15%, and 30% natural aggregate substitution with RCA. Following 28 days of curing, samples underwent direct fire exposure in a melting furnace. Temperature progression was monitored using a pyrometer, ranging from ambient (0 °C) through 250 °C, 400 °C, 600 °C, to 800 °C, with controlled exposure duration at each level. Three samples were tested at each temperature. After fire exposure, samples were cooled for 24 h at ambient temperature before compression testing. The densities of the fresh specimens were determined to be 2254.06 kg/m³ for HS-0AR%, 2210.09 kg/m³ for HS-15AR%, and 2180.85 kg/m³ for HS-30AR%, with a percentage density variation with respect to HS-0AR% of 1.95% and 3.25%, respectively. Finally, in relation to the compressive strength of concrete, a reduction of 4.34% was observed for 15% AGR and 5.72% for 30%, suggesting that the variations may be due to factors such as the water/cement ratio, the quality of the aggregate, and the curing conditions of concrete. In addition, several pathologies were observed, such as cracking, fissures, color changes, and spalling. Full article