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Search Results (261)

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Keywords = special cement

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10 pages, 1668 KiB  
Case Report
Novel Surgical Reconstruction Using a 3D Printed Cement Mold Following Resection of a Rare Case of Proximal Ulna Osteosarcoma: A Case Report and Description of the Surgical Technique
by Abdulrahman Alaseem, Hisham A. Alsanawi, Waleed Albishi, Ibrahim Alshaygy, Sara Alhomaidhi, Mohammad K. Almashouq, Abdulaziz M. AlSudairi, Yazeed A. Alsehibani and Abdulaziz O. Almuhanna
Curr. Oncol. 2025, 32(8), 411; https://doi.org/10.3390/curroncol32080411 - 22 Jul 2025
Viewed by 220
Abstract
Osteosarcoma is one of the most common primary bone malignancies, typically occurring around the knee. However, the forearm is a rare site, with tumors in the proximal ulna being extremely uncommon. Primary sarcoma in this location presents a surgical challenge due to the [...] Read more.
Osteosarcoma is one of the most common primary bone malignancies, typically occurring around the knee. However, the forearm is a rare site, with tumors in the proximal ulna being extremely uncommon. Primary sarcoma in this location presents a surgical challenge due to the complex anatomy and limited reconstructive options. We report a rare case of a 19-year-old female with non-metastatic, high-grade giant cell-rich osteosarcoma involving the right proximal ulna. To our knowledge, this is only the second reported adult case of this histological subtype in this location. The patient was treated at a specialized oncology center with neoadjuvant and adjuvant chemotherapy, along with wide intra-articular resection for local tumor control. Reconstruction was achieved using a novel, customized 3D-printed articulating cement spacer mold with plate osteosynthesis. Artificial elbow ligamentous reconstruction was performed using FiberTape and FiberWire sutures passed through drill holes, and the triceps tendon was reattached to the cement mold using an endobutton. This cost-effective and personalized surgical approach allowed successful joint reconstruction while maintaining elbow stability and function. Our case highlights a feasible reconstructive option for rare and anatomically challenging osteosarcoma presentations, contributing to the limited literature on proximal ulna giant cell-rich osteosarcoma. Full article
(This article belongs to the Section Bone and Soft Tissue Oncology)
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32 pages, 5792 KiB  
Article
Special Cement-Based Grouting Material for Subway Structure Repair During Operation Performance Sensitivity Analysis
by Wei Song, Xiaokai Niu, Zhitian Xie, He Wang, Jie Su and Chentao Xu
Buildings 2025, 15(14), 2396; https://doi.org/10.3390/buildings15142396 - 8 Jul 2025
Viewed by 190
Abstract
This study uses ordinary Portland–sulfate–silicate composite cement as the matrix and investigates the effects of water–cement ratio, HPMC dosage, and PCS dosage on the performance of specialized grouting materials for subway structure repair during operation through single-factor experiments and orthogonal experiments. Multifactorial variance [...] Read more.
This study uses ordinary Portland–sulfate–silicate composite cement as the matrix and investigates the effects of water–cement ratio, HPMC dosage, and PCS dosage on the performance of specialized grouting materials for subway structure repair during operation through single-factor experiments and orthogonal experiments. Multifactorial variance analysis was employed to quantitatively evaluate the sensitivity of each factor and their interactions to slurry flowability, setting time, anti-dispersibility, and compressive strength. The results show that the water–cement ratio is the most critical factor affecting the performance of the grouting material, with extremely significant impacts on all performance indicators; HPMC dosage significantly affects flowability, setting time, and anti-dispersibility; PCS dosage primarily influences 2 h compressive strength; the interaction between water–cement ratio and HPMC dosage has a significant impact on anti-dispersibility. Principal component analysis revealed the trade-off relationship between flowability, setting time, and strength. The study established a sensitivity ranking for the performance of specialized grouting materials: water–cement ratio > HPMC dosage > PCS dosage > interaction, providing a theoretical basis and methodological reference for the formulation optimization of specialized grouting materials for subway structure repair during operation. Full article
(This article belongs to the Section Building Materials, and Repair & Renovation)
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20 pages, 6030 KiB  
Review
Review of Component Materials and Diverse Applications of Polymer Concrete
by Xiaolei Li, Jinyuan Gu, Yunsheng Xu, Shen Li and Rui Zhang
Materials 2025, 18(12), 2745; https://doi.org/10.3390/ma18122745 - 11 Jun 2025
Viewed by 444
Abstract
Polymer concrete (PC) refers to the use of a polymer as a replacement for cement, enhancing the mechanical and durability properties of traditional concrete. Introduced in the late 1950s and gaining prominence in the 1970s, the use of PCs has been rapidly increasing [...] Read more.
Polymer concrete (PC) refers to the use of a polymer as a replacement for cement, enhancing the mechanical and durability properties of traditional concrete. Introduced in the late 1950s and gaining prominence in the 1970s, the use of PCs has been rapidly increasing across various industries. This paper provides a comprehensive review, beginning with a brief historical overview of polymer concrete. It examines key review papers and books related to PC, summarizing the various materials commonly used in its formulation, such as resins, fillers, fibers, and nanofillers. Additionally, the paper explores the diverse applications of polymer concrete, ranging from structural repairs and architectural cladding to advanced uses in electrical insulation and 3D printing, with special attention given to sustainability aspects. Through this review, the paper highlights the growing importance of polymer concrete in modern construction and infrastructure projects. Full article
(This article belongs to the Special Issue Recent Progress in Sustainable Construction Materials)
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19 pages, 7054 KiB  
Article
Synthesis and Performance Evaluation of Anti-Washout Admixtures for Underwater Non-Dispersive Concrete Based on Nanosilica
by Jian Wang, Kaijian Huang, Hongyan Chu and Jianhui Li
Materials 2025, 18(11), 2541; https://doi.org/10.3390/ma18112541 - 28 May 2025
Viewed by 384
Abstract
Anti-washout admixtures (AWAs) are a unique component of underwater non-dispersive concrete (UNDC), which gives the concrete the ability to remain undispersed in water. On some special occasions, freshly mixed underwater non-dispersive concrete is exposed to the erosion of moving water, and conventional acrylamide-based [...] Read more.
Anti-washout admixtures (AWAs) are a unique component of underwater non-dispersive concrete (UNDC), which gives the concrete the ability to remain undispersed in water. On some special occasions, freshly mixed underwater non-dispersive concrete is exposed to the erosion of moving water, and conventional acrylamide-based AWAs are only suitable for static water or the water flow rate is small. In this study, the inorganic component nanosilica (NS) is modified, treated, and copolymerized with the organic components acrylamide (AM) and acrylic acid (AA) to form an inorganic–organic hybrid polymer with a hyperbranched structure, which changes the linear structure of the original polyacrylamide molecule, and we optimize the synthesis process. The polymers are characterized at the microscopic level and their compatibility with polycarboxylic acid water-reducing agents (SP) is investigated. In addition, the polymers are compared and evaluated with commonly used PAM in terms of their working performance. The experimental results indicated that under specific process conditions, polymers endow cement mortar with good resistance to water erosion. At the same time, the polymers’ three-dimensional network structure is prominent, with good compatibility with SP and better anti-dispersity. The microstructure of the cement paste with added polymers is dense and flat, but its flowability and setting time are slightly worse. This study provides a new development direction for the development of AWAs under a dynamic water environment, which has specific engineering significance. Full article
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20 pages, 9994 KiB  
Article
Reservoir Development and Well Operation Control Methods: Practical Application
by Ryskol Bayamirova, Aliya Togasheva, Danabek Saduakasov, Akshyryn Zholbasarova, Maxat Tabylganov, Aigul Gusmanova, Manshuk Sarbopeeva, Bibigul Nauyryzova and Shyngys Nugumarov
Processes 2025, 13(5), 1541; https://doi.org/10.3390/pr13051541 - 16 May 2025
Viewed by 467
Abstract
The study aims to improve the efficiency of oil field development at the Kalamkas field through the implementation of new methods for analyzing hydrodynamic survey data and monitoring well conditions. It is hypothesized that the use of integrated geophysical and hydrodynamic methods will [...] Read more.
The study aims to improve the efficiency of oil field development at the Kalamkas field through the implementation of new methods for analyzing hydrodynamic survey data and monitoring well conditions. It is hypothesized that the use of integrated geophysical and hydrodynamic methods will enhance forecasting accuracy, optimize field operations, and increase the hydrocarbon recovery factor. An integrated approach combining pulsed neutron logging (PNL), acoustic cementometry (AC), inflow and injectivity profile evaluation methods, and specialized software for advanced data interpretation was applied, significantly improving the accuracy of well condition analysis. The analysis enabled the identification of oil and gas saturation intervals, zones of increased water cut, and cementing defects in casing, and allowed for a quantitative assessment of reservoir permeability dynamics. Hydraulic fracturing application resulted in a 10–15% increase in permeability in certain zones, with an average oil recovery factor increase of 5%. Analysis of PNL data demonstrated the transition of oil-saturated reservoirs to water saturation during development, confirmed by geophysical and pressure build-up survey results. The study identified the primary causes of increased water cut and key factors leading to production rate decline. Proposed measures for optimizing operating modes and well grid efficiency contribute to improving existing field management practices. Full article
(This article belongs to the Section Energy Systems)
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22 pages, 6349 KiB  
Article
Influence of Different Binders on the Municipal Solid Waste Incineration Fly Ash Granulation-Based Stabilization Process
by Maryna Shevtsova, Jurgita Malaiškienė, Jelena Škamat and Valentin Antonovič
Sustainability 2025, 17(10), 4573; https://doi.org/10.3390/su17104573 - 16 May 2025
Viewed by 555
Abstract
Municipal solid waste incineration fly ash (MSWI FA) is a hazardous waste that must be kept in special landfills due to the high amounts of chlorides, sulfates, and heavy metals. The granulation of MSWI FA could be used as a solidification/stabilization (S/S) of [...] Read more.
Municipal solid waste incineration fly ash (MSWI FA) is a hazardous waste that must be kept in special landfills due to the high amounts of chlorides, sulfates, and heavy metals. The granulation of MSWI FA could be used as a solidification/stabilization (S/S) of fly ash to immobilize hazardous chemical elements and to reduce dust emissions. In this work for granulation, three different binders were used: calcium aluminate cement (CAC), geopolymer (GEO), and Portland cement (PC). Chemical (XRF), mineral (XRD), granulometric compositions, and leaching of prepared granules are presented in the article. Furthermore, the impact of different binders on bulk density, compressive strength, and granule structure was analyzed. The results show that the granules with CAC binder have the best initial compressive strength (about 10 MPa), but these granules were destroyed after the leaching test or connection with water. The geopolymer as a binder did not provide the required compressive strength and immobilization of harmful elements. Granules with a Portland cement binder have a suitable compressive strength, a slight leaching of chemical elements, and good durability in the alkaline and acidic environment; they are also resistant to freezing and thawing cycles. Full article
(This article belongs to the Section Waste and Recycling)
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37 pages, 6284 KiB  
Systematic Review
Valorization of Medical Waste in Cement-Based Construction Materials: A Systematic Review
by M. Murillo, S. Manzano, Y. F. Silva, C. Burbano-García and G. Araya-Letelier
Buildings 2025, 15(10), 1643; https://doi.org/10.3390/buildings15101643 - 13 May 2025
Viewed by 913
Abstract
Worldwide, the healthcare industry produces massive quantities of medical waste (MW), most of which is incinerated, releasing large quantities of dioxins, mercury, and other pollutants. Despite this, only a limited number of studies have explored the incorporation of MW into construction materials, with [...] Read more.
Worldwide, the healthcare industry produces massive quantities of medical waste (MW), most of which is incinerated, releasing large quantities of dioxins, mercury, and other pollutants. Despite this, only a limited number of studies have explored the incorporation of MW into construction materials, with a special focus on cement-based construction materials (CB-CMs). However, to the best of the authors’ knowledge, no existing review formally structures, summarizes, correlates, and discusses the findings of previous studies on MW in CB-CMs to encourage further research and applications of this promising alternative. Therefore, the added value of this study lies in providing an innovative and critical analysis of existing research on the use of MW in CB-CMs, consolidating and evaluating dispersed findings through a systematic literature review, enhancing understanding of the topic, and identifying knowledge gaps to guide future research. A robust systematic literature review was conducted, encompassing 40 peer-reviewed research articles, retrieved from the Web of Science Core Collection database. The methodology involved a three-stage process: a descriptive analysis of the included articles, the identification and synthesis of key thematic areas, and a critical evaluation of the data to ensure a rigorous and systematic report. The selection criteria prioritized peer-reviewed research articles in English with full text availability published in the last 7 years, explicitly excluding conference papers, book chapters, short reports, and articles not meeting the language or accessibility requirements. The results indicate that the influence of MW in CB-CM varies significantly. For example, while the incorporation of face masks as fiber reinforcement in concrete generally enhances its mechanical and durability properties, the use of gloves is less effective and not always recommended. Finally, it was found that further research is needed in this field due to its novelty. Full article
(This article belongs to the Section Building Materials, and Repair & Renovation)
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19 pages, 5048 KiB  
Article
Stabilization of Clay Subgrade Soil by Using Waste Foundry Sand with a Geogrid
by Qais Sahib Banyhussan, Jaafar Abdulrazzaq, Ahmed A. Hussein, Anmar Dulaimi, Jorge Miguel de Almeida Andrade and Luís Filipe Almeida Bernardo
CivilEng 2025, 6(2), 26; https://doi.org/10.3390/civileng6020026 - 10 May 2025
Viewed by 1121
Abstract
Various stabilizers, such as jute, gypsum, rice-husk ash, fly ash, cement, lime, and discarded rubber tires, are commonly used to improve the shear strength and overall characteristics of clay subgrade soil. In this study, waste foundry sand (WFS) is utilized as a stabilizing [...] Read more.
Various stabilizers, such as jute, gypsum, rice-husk ash, fly ash, cement, lime, and discarded rubber tires, are commonly used to improve the shear strength and overall characteristics of clay subgrade soil. In this study, waste foundry sand (WFS) is utilized as a stabilizing material to enhance the properties of clay subgrade soil and strengthen the bond between clay subgrade soil and subbase material. The materials employed in this study include Type B subbase granular materials, clay subgrade soil, and 1100 Biaxial Geogrid for reinforcement. The clay subgrade soil was collected from the airport area in the Al-Muthanna region of Baghdad. To evaluate the effectiveness of WFS as a stabilizer, soil specimens were prepared with varying replacement levels of 0%, 5%, 10%, and 15%. This study conducted a Modified Proctor Test, a California Bearing Ratio test, and a large-scale direct shear test to determine key parameters, including the CBR value, maximum dry density, optimum moisture content, and the compressive strength of the soil mixture. A specially designed large-scale direct shear apparatus was manufactured and utilized for testing, which comprised an upper square box measuring 20 cm × 20 cm × 10 cm and a lower rectangular box with dimensions of 200 mm × 250 mm × 100 mm. The findings indicate that the interface shear strength and overall properties of the clay subgrade soil improve as the proportion of WFS increases. Full article
(This article belongs to the Section Geotechnical, Geological and Environmental Engineering)
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22 pages, 4241 KiB  
Article
Impact of Alkali-Activated Tannery Sludge-Derived Geopolymer Gel on Cement Properties: Workability, Hydration Process, and Compressive Strength
by Shoukai Chen, Beiying Liu, Phu Minh Vuong Nguyen, Jinping Liu, Jialin Chen and Fei Zhou
Gels 2025, 11(5), 339; https://doi.org/10.3390/gels11050339 - 1 May 2025
Viewed by 443
Abstract
The utilization of tannery sludge (TS) in construction materials not only effectively reduces pollution and resource consumption associated with waste disposal, but also promotes low carbon transformation in the building materials sector, further advancing sustainable development of green construction. This study aims to [...] Read more.
The utilization of tannery sludge (TS) in construction materials not only effectively reduces pollution and resource consumption associated with waste disposal, but also promotes low carbon transformation in the building materials sector, further advancing sustainable development of green construction. This study aims to investigate the impact of sludge-based geopolymer gel on cementitious material performance, revealing the evolution mechanisms of material fluidity, setting time, hydration process, and compressive strength under the coupled effects of tannery sludge and alkali activation, thereby providing a reusable technical pathway to address the resource utilization challenges of similar special solid wastes. A series of alkali-activated composite cementitious materials (AACC) were prepared in the study by partially substituting cement with alkaline activators, TS, and fly ash (FA), through adjustments in TS–FA ratios and alkali equivalent (AE) variations. The workability, hydration process, and compressive strength evolution of AACC were systematically investigated. The experimental results indicated that as the TS content increased from 0% to 100%, the fluidity of fresh AACC decreased from 147 mm to 87 mm, while the initial and final setting times exhibited an exponential upward trend. The incorporation of TS was found to inhibit cement hydration, though this adverse effect could be mitigated by alkaline activation. Notably, 20–40% sludge dosages (SD) enhanced early-age compressive strength. Specifically, the compressive strength of the 0% TS group at 3 d age was 24.3 MPa, that of the 20% TS group was 25.9 MPa (an increase rate of 6.58%), and that of the 40% TS group was 24.5 MPa (an increase rate of 0.82%), whereas excessive additions resulted in the reduction of hydration products content and diminished later stage strength development. Furthermore, the investigation into AE effects revealed that maximum compressive strength (37.4 MPa) was achieved at 9% AE. These findings provide critical data support for realizing effective utilization of industrial solid wastes. Full article
(This article belongs to the Section Gel Processing and Engineering)
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26 pages, 32560 KiB  
Article
Sustainable Production of Building Blocks by Reusing Stone Waste Sludge
by Albina Scioti, Francesco Fabbrocino and Fabio Fatiguso
Appl. Sci. 2025, 15(9), 5031; https://doi.org/10.3390/app15095031 - 30 Apr 2025
Cited by 1 | Viewed by 481
Abstract
Mining and stone processing activities generate a large amount of various types of waste. Among these, Stone Waste Sludge (SWS) constitutes 22.5 percent of the raw material processed and is disposed of by delivering it to now disused quarries with significant landscape and [...] Read more.
Mining and stone processing activities generate a large amount of various types of waste. Among these, Stone Waste Sludge (SWS) constitutes 22.5 percent of the raw material processed and is disposed of by delivering it to now disused quarries with significant landscape and environmental consequences. This paper describes research aimed at identifying the possible uses of this waste, transforming it from a waste to a resource for the production of building blocks. The production of such building blocks is based on historical preparations of mixtures for artificial stone and is developed through an experimental approach and a simple and economical production methodology. Mixes consisting mainly of SWS and Portland cement (PC) were designed and tested. The aggregates and PC were mixed, wetted, and compacted under high pressure in special molds to form the specimens. The design of the mixtures and related tests aimed to define the process parameters considered such as the amount of water (W), the ratio of PC to SWS, and the compaction pressure. The compressive strength of the manufactured specimens at the age of 28 days was identified as the response variable. The results indicated that all of the mixtures had high mechanical strength values even when using high amounts of SWS relative to the amount of PC and that all of them have excellent characteristics for use as building elements in construction. This implies that such waste has an excellent potential for large-scale reuse in construction and encourages further research and testing, both in terms of the thermo-hygrometric properties of such elements and in terms of LCA analysis. Full article
(This article belongs to the Section Civil Engineering)
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26 pages, 14906 KiB  
Review
Advances in the Application and Mechanism of Admixtures and Industrial By-Products in Cement-Based Self-Leveling Mortar: A Comprehensive Review
by Meirong Zong, Haozhe Ma, Xiancui Yan, Pinghua Zhu, Wenhao Wang, Hui Liu, Faqin Dong and Minqi Hua
Materials 2025, 18(8), 1709; https://doi.org/10.3390/ma18081709 - 9 Apr 2025
Viewed by 542
Abstract
Cement-based self-leveling mortar (CSL) is a special building material that utilizes cement as the main cementitious component, combined with a variety of admixtures. Its self-leveling characteristics enable it to effectively level and fill uneven surfaces. Additionally, the innovative green CSL developed from industrial [...] Read more.
Cement-based self-leveling mortar (CSL) is a special building material that utilizes cement as the main cementitious component, combined with a variety of admixtures. Its self-leveling characteristics enable it to effectively level and fill uneven surfaces. Additionally, the innovative green CSL developed from industrial by-products can further enhance both environmental and economic benefits. This paper systematically reviews the use of admixtures and industrial by-products in the production of CSL. The main findings include the following: (i) compared to the international ISO standard, China’s standard JC/T 985 provides more detailed testing parameters regarding fluidity, mechanical properties, and shrinkage; (ii) the effect of additives on CSL is affected by its molecular weight and structure, and high molecular weight improving the workability of the additives; (iii) industrial by-products have been effectively incorporated into CSL, leading to a reduction in reduced greenhouse gas emissions and a decreased environmental impact; (iv) macro and microanalysis results of different green CSLs show that industrial by-product gypsum has the greatest potential for application in CSL. Based on these findings, this paper offers valuable reference data for the use of admixtures and industrial by-products in CSL. Furthermore, it contributes innovatively to the sustainable development of infrastructure construction. Full article
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15 pages, 2137 KiB  
Article
Ecological Concrete-Based Modular System for Heavy Metal Removal in Riparian Transition Zones: Design, Optimization and Performance Evaluation
by Guangbing Liu, Da Ke, Hasnain Moavia, Chen Ling, Yanhong Zhang and Yu Shen
Appl. Sci. 2025, 15(7), 3721; https://doi.org/10.3390/app15073721 - 28 Mar 2025
Viewed by 388
Abstract
This study presents the development and evaluation of an innovative modular ecological transition zone system for riparian restoration. Through systematic optimization, we developed a C25-grade ecological concrete module (100 mm × 100 mm × 100 mm) with a specialized cavity design (φ61 mm [...] Read more.
This study presents the development and evaluation of an innovative modular ecological transition zone system for riparian restoration. Through systematic optimization, we developed a C25-grade ecological concrete module (100 mm × 100 mm × 100 mm) with a specialized cavity design (φ61 mm × H60 mm) that achieves optimal balance between structural integrity (20–30 MPa compressive strength) and environmental functionality (>15% porosity, >1 × 10−4 cm s−1 permeability). The module incorporates precisely calibrated proportions of cement (378 kg m−3), reinforcing agent (12 kg m−3), aggregate (1650 kg m−3), and water (137 L m−3), creating a robust platform for environmental remediation. The system was evaluated at two scales: module-scale experiments in 25 L containers (833:1 mL g−1 ratio) and kinetic studies (10:1 mL g−1 ratio), revealing a sophisticated three-phase removal process. The initial rapid surface adsorption phase (0–4 h) achieved removal rates of 0.28–0.42 mg g−1 h−1, followed by pore diffusion (4–24 h) and chemical fixation phases, with removal patterns effectively modeled using a modified pseudo-second-order equation. The system demonstrated exceptional heavy metal removal capabilities across varying concentration ranges, achieving removal efficiencies of 95.6% for Pb2+ ions, 92.3% for Cd2+ ions, 84.2% for Cr3+ ions, 89.7% for Cu2+ ions, and 84.8% for Zn2+ ions under optimal conditions. Performance remained robust across two orders of magnitude in concentration ranges, with removal efficiencies maintaining above 80% at both experimental scales. The modular design’s cost-effectiveness is demonstrated through material costs of USD 45–60 m−3, with operational costs 40–60% lower than conventional systems. This research provides a practical, cost-effective solution for riparian zone restoration, combining structural durability with efficient pollutant removal capabilities while maintaining consistent performance across varying environmental conditions. Full article
(This article belongs to the Special Issue Recent Advances in Asphalt Materials and Their Applications)
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13 pages, 1730 KiB  
Article
Pediatric Preformed Zirconium Oxide Crowns vs. Preformed Metal Crowns After Pulpotomy in Primary Molars: A Practice-Based Retrospective 2.5 Year Cohort Study
by Isabella Brenner, Maria Abdin and Julian Schmoeckel
Healthcare 2025, 13(7), 751; https://doi.org/10.3390/healthcare13070751 - 27 Mar 2025
Viewed by 860
Abstract
Background: Primary molars with deep carious lesions often require a treatment with pulpotomy and restoration with a crown. Aim: This study aims to compare the survival rates of stainless steel (SSC) and zirconium oxide (ZOC) crowns carried out on pulpotomized primary molars using [...] Read more.
Background: Primary molars with deep carious lesions often require a treatment with pulpotomy and restoration with a crown. Aim: This study aims to compare the survival rates of stainless steel (SSC) and zirconium oxide (ZOC) crowns carried out on pulpotomized primary molars using the International Caries Detection and Assessment System (ICDAS) 4 to 6 lesions. Materials and Methods: The data of 100 patients (mean age 5.3 ± 2.1 years, mean decayed, missing or filled primary teeth (dmft) 7.1 ± 3.2) with 272 primary molars (40, 225, 7 with ICDAS 4, 5, 6, respectively) were collected retrospectively from a specialized private pediatric dental office after ethical approval was obtained and each participant agreed to participation in the study. Primary molars were treated between 2019 and 2021 with pulpotomy (15.5% ferrous sulfate solution for hemostasis and zinc oxide eugenol as a wound dressing) followed by a crown (203 SSC and 69 ZOC) with a minimum follow-up period of 6 months and a mean follow-up time of 28.2 (±11.0) months. Results: Failure occurred significantly less often in SSC (n = 13 out of 203) than in ZOC (n = 20 out of 69; p < 0.001). Major failure was attributed to swelling and abscess (n = 13, 39.4%) followed by the occurrence of fistula (n = 15, 45.4%) and fracture of the crown and abutment (n = 5, 15.2%). Minor failure due to cement dissolution occurred significantly less often in SSC than in ZOC (n = 10 out of 203 vs. n = 9 out of 69; p < 0.005. A Kaplan–Meier survival analysis showed an overall estimated survival time of 38.25 (Confidence interval (CI): 37.0–39.4) months for both types of crowns. A Log-Rank (Mantel–Cox) analysis showed a statistically significant difference (p < 0.05) in the estimated mean survival time of SSC (39.75; CI: 38.5–40.9 months) and ZOC (33.4; CI: 30.5–36.3 months). Survival probability drops just below 80% for ZOC and stays a little over 90% for SCC around the 20th month. Conclusions: SSC showed an advantage over its ZOC counterpart when placed after pulpotomy for the management of primary molars with deep carious lesions. A higher necessity for re-intervention in the more aesthetic ZOC should be considered in clinical decision taking. Full article
(This article belongs to the Special Issue Prevention and Management of Oral Diseases Among Children)
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23 pages, 11405 KiB  
Review
An Overview of the Main Types of Damage and the Retrofitting of Reinforced Concrete Bridges
by Andrii Klym, Yaroslav Blikharskyy, Volodymyr Gunka, Olha Poliak, Jacek Selejdak and Zinoviy Blikharskyy
Sustainability 2025, 17(6), 2506; https://doi.org/10.3390/su17062506 - 12 Mar 2025
Cited by 4 | Viewed by 1012
Abstract
Restoring and strengthening existing bridges is more economically and environmentally feasible, as cement production in new RC bridges significantly contributes to CO2 emissions. Additionally, the production of composite carbon materials for strengthening RC structures does not require a large amount of energy, [...] Read more.
Restoring and strengthening existing bridges is more economically and environmentally feasible, as cement production in new RC bridges significantly contributes to CO2 emissions. Additionally, the production of composite carbon materials for strengthening RC structures does not require a large amount of energy, unlike the production of steel for reinforcement, which requires a significant amount of electricity and, accordingly, causes a significant amount of CO2 emissions. This is why this article presents a comprehensive review of the damage, calculations, and strengthening of RC bridge structures. It examines the main types of damage, including mechanical impacts, material fatigue, corrosion processes, seismic actions, and thermal loads. The mechanisms of their formation, correlations with environmental factors, and operational conditions are detailed. Examples of damage from real engineering objects are provided to assess the scale of the problem. Approaches to the calculation of RC bridge structures are analyzed, particularly methods for modeling the stress–strain state, considering crack formation and material degradation. Key studies by Ukrainian and foreign researchers are highlighted, identifying areas for further methodological improvement. Special attention is given to traditional and modern strengthening methods, including the use of steel elements, composites, and carbon strips. A comparative analysis of the effectiveness of different strengthening approaches is conducted. The conclusion emphasizes the need for further development of existing diagnostic, calculation, and strengthening methods. The integration of innovative materials and technologies is particularly relevant for enhancing the durability of bridges under modern operational loads. Full article
(This article belongs to the Special Issue Sustainable Road Construction Materials: Challenges & Innovations)
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22 pages, 7746 KiB  
Article
Study on the Mechanism of Mechanical Properties and Wind Leakage Sealing Effect of KH570-Enhanced VAE/Cement Materials
by Qingsong Zhang, Huaqiang Sheng, Jinliang Li, Jinhu Li and Hao Zhang
Materials 2025, 18(6), 1205; https://doi.org/10.3390/ma18061205 - 7 Mar 2025
Viewed by 981
Abstract
In order to address the issue of wind leakage leading to spontaneous coal combustion in goafs during gob-side entry mining, a KH570 silane coupling agent (SCA)-modified vinyl acetate–ethylene (VAE)/cement-based flexible spraying sealing material was developed. The mechanical properties and wind leakage sealing performance [...] Read more.
In order to address the issue of wind leakage leading to spontaneous coal combustion in goafs during gob-side entry mining, a KH570 silane coupling agent (SCA)-modified vinyl acetate–ethylene (VAE)/cement-based flexible spraying sealing material was developed. The mechanical properties and wind leakage sealing performance of the material were evaluated using specialized testing equipment. Furthermore, molecular dynamics simulations and microstructural characterization techniques were utilized to assess and model the interface compatibility of the material. The experimental results demonstrate that KH570 significantly enhanced the material’s mechanical properties. Following modification, the material exhibited increases in the maximum tensile strength, compressive strength, and flexural strength by 53%, 38%, and 29%, respectively. KH570 not only promotes the formation of additional calcium silicate hydrate (C-S-H) gel through cement hydration, but also establishes Si-O-Si chemical bonds with cement hydration products and hydrogen bonds with the VAE emulsion. This functions as a “molecular bridge”, significantly enhancing the interface performance of the composite. The interaction between the organic and inorganic phases contributes to the formation of an interpenetrating network structure, imparting excellent compressive, flexural, and tensile deformation resistance to the material. The wind leakage of the spray-modified material was reduced by 2.7 times compared to the unmodified material, significantly improving its sealing performance under mining-induced pressure conditions. This enhancement effectively minimizes spontaneous combustion in mined-out coal areas caused by wind leakage, thereby ensuring safer mining operations. Full article
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