Search Results (535)

Background: Autologous platelet concentrates, including platelet-rich fibrin (PRF) matrices, have been proposed as biologically active scaffolds for vital pulp therapy. Evidence on the clinical use of different solid PRF matrices for direct pulp capping remains limited. Objective: The aim of this study is to describe and monitor two clinical cases of reversible pulpitis treated with direct pulp capping using two PRF membranes prepared by different centrifugation approaches, namely advanced platelet-rich fibrin plus (A-PRF+) and horizontal platelet-rich fibrin plus (H-PRF). Methods: In Case 1, A-PRF+ was prepared using a fixed-angle centrifugation protocol; in Case 2, H-PRF was prepared using a horizontal centrifugation protocol. In both cases, deep carious lesions with small carious pulp exposures (<1.5 mm) were managed by caries removal, ozone-assisted dentin disinfection, and direct pulp capping with the respective PRF membrane, followed by temporary calcium-silicate cement definitive coronal restoration. Clinical and radiographic follow-up, including cone-beam computed tomography, was performed for up to 12 months. Results: In Case 1 (A-PRF+), reparative dentin bridge formation was confirmed at 90 days, with a thickness of 0.2 mm. In Case 2 (H-PRF), reparative dentin was observed within 46 days, with a thickness of 0.28 mm. In both cases, pulp vitality was maintained, and no clinical symptoms or periapical changes were detected during the 12-month follow-up. Conclusions: These two cases suggest that direct pulp capping using PRF membranes (A-PRF+ or H-PRF), combined with ozone-assisted dentin disinfection and adequate coronal sealing, may be associated with maintained pulp vitality and hard-tissue repair after carious pulp exposure diagnosed as reversible pulpitis. Due to the descriptive two-case design and major confounding factors (including age and lesion characteristics), no comparative conclusions can be drawn. Prospective controlled clinical studies with standardized protocols are warranted. Full article

Rubber particles have been proven to have the advantages of improving the energy absorption effect and enhancing the friction between soil particles when used to modify the soil. The rubber-modified soil technology also provides a new solution for the pollution-free disposal of waste rubber. However, when rubber particles are used to modify collapsible loess, they cannot significantly enhance its strength. Previous studies have not systematically clarified whether combining rubber particles with different cementation mechanisms can overcome this limitation, nor compared their shear mechanical effectiveness under identical conditions. In view of this, a dual synergistic strategy is implemented by combining rubber with lime and rubber with enzyme-induced calcium carbonate precipitation (EICP). Direct shear tests and scanning electron microscopy are used to evaluate four modification approaches: rubber alone, lime alone, rubber with EICP, and rubber with lime. Accordingly, shear strength, cohesion, and internal friction angle are quantified. At a vertical normal stress of 100 kPa and above, samples modified with rubber and lime (7–9% lime and 6–8% rubber) achieve peak shear strength values of 200–203 kPa, representing an 86.4% increase compared to rubber alone. Microscopic analysis reveals that calcium silicate hydrate gel effectively anchored rubber particles, forming a composite structure with a rigid skeleton and elastic buffer. In comparison, the rubber and EICP group (10% rubber) shows a substantial increase in internal friction angle (24.25°) but only a modest improvement in cohesion (16.5%), which is due to limited continuity in the calcium carbonate bonding network. It should be noted that the performance of EICP-based modification is constrained by curing efficiency and reaction continuity, which may affect its scalability in conventional engineering applications. Overall, the combination of rubber and lime provided an optimal balance of strength, ductility, and construction efficiency. Meanwhile, the rubber and EICP method demonstrates notable advantages in environmental compatibility and long-term durability, making it suitable for ecologically sensitive applications. The results offer a framework for loess stabilization based on performance adaptation and resource recycling, supporting sustainable use of waste rubber in geotechnical engineering. Full article

Vital pulp therapy (VPT) is increasingly recognised as a biologically driven alternative to root canal treatment in teeth with deep caries and a vital pulp diagnosis. Resin-modified calcium silicate-based materials (RM-CSMs) were introduced to combine the bioactivity of traditional cements with improved handling and immediate light-curing, but their biological performance remains debated. Objectives: This systematic review and meta-analysis aimed to evaluate the clinical and radiographic outcomes of VPT performed with RM-CSMs compared with conventional non-resin-modified calcium silicate-based materials (NRM-CSMs) Methods: PRISMA Guidelines were followed to carry out this systematic review. Electronic databases (Medline, Embase, Scopus, and Web of Science) were searched up to October 2025 for randomised clinical trials evaluating indirect pulp capping, direct pulp capping, or pulpotomy. Nine trials met the inclusion criteria. Meta-analyses were performed for TheraCal LC, the only RM-CSM with sufficient clinical evidence. The risk of bias was assessed using the RoB 2 Tool. The certainty of evidence was assessed using GRADE. Results: Pooled results showed no significant differences in overall clinical–radiographic success between RM-CSMs and NRM-CSMs at 90 or 180 days. At 360 days, a trend favouring NRM-CSMs emerged, though not statistically significant. Dentine bridge formation at 360 days was significantly lower with TheraCal LC. Conclusions: Current RM-CSMs demonstrate comparable short-term success to conventional materials but still present biological limitations, particularly regarding long-term reparative outcomes. NRM-CSMs remain the preferred option when maximal bioactivity and predictable dentinogenesis are required Full article

The construction industry faces growing pressure to adopt sustainable materials due to the high CO₂ emissions associated with ordinary Portland cement (OPC) production. Geopolymers synthesized from industrial by-products such as fly ash offer a promising low-carbon alternative. However, the extensive use of commercial sodium silicate (SSC) as an activator remains constrained by its high cost and energy-intensive manufacturing. This study investigates a silica fume-derived sodium silicate alternative (SSA) combined with NaOH as a more sustainable activator for fly ash-based geopolymer mortar. Mortars were prepared with alkali activator-to-precursor (AA/P) ratios of 0.7 and 0.5 and cured at 65 °C and 80 °C. SSA-based mixes exhibited comparable flowability to SSC-based mortars, with slightly longer setting times making them favorable for placement. Mechanical tests showed the superior performance of SSA systems, with AS0.7-65 achieving the highest compressive strength and AS0.7-80 demonstrating greater flexural and tensile strength. Microstructural analyses (SEM, EDX, ATR-FTIR) revealed denser matrices and enhanced sodium aluminosilicate hydrate (N-A-S-H) and calcium-rich N(C)-A-S-H gel formation. Economic assessment indicated approximately 30% cost reduction and a modest (~2%) decrease in CO₂ emissions. These findings highlight SSA as a technically viable and sustainable activator for next-generation geopolymer construction. Full article

Calcium magnesium phosphate cements (CMPCs) were obtained starting from dolomite (alone or mixed with fly ash) thermally treated at two different temperatures. Dolomite calcination at 750 °C for 3 h determined the formation of a mixture of MgO and CaCO₃. The mixing of dolomite with fly ash and the increase in the calcination temperature at 1200 °C determined the formation of new compounds (calcium aluminum silicate and calcium magnesium silicates), which are present along with MgO and small amounts of CaO in the thermally treated material. These two precursors were mixed with KH₂PO₄ solution and borax (as a retardant admixture) to obtain the CMPCs. The setting time and compressive strengths of these CMPCs were assessed and the XRD analyses provided insights into their mineralogical composition after hardening and thermal treatment. The cements, as so or mixed with perlite, were applied on steel plates, to assess their behavior when put in direct contact with a flame. The compatibility of these materials with the steel substrate was evaluated by scanning electron microscopy (SEM). The direct contact with the flame up to 60 min provided information regarding the CMPCs’ ability to prevent the rapid increase in the substrate (steel plate) temperature. The findings indicate that CMPC pastes and composites containing perlite can offer a degree of protection for steel structures in the event of a fire. Full article

This paper examined the effect of marble powder (MP) on air-cured cement-based materials when subjected to sulfuric acid (H₂SO₄) attack. Four MP replacement levels were tested: 0%, 5%, 10%, and 15% by weight of cement. The prepared samples were cured for 90 days prior to being exposed to H₂SO₄. Macroscopic tests for apparent density and compressive strength along with microstructural characterization using X-ray diffraction (XRD) and scanning electron microscopy (SEM) were performed to determine the effect of MP on the properties of the materials. The Rietveld method was used to analyze the amounts of different crystalline phases and amorphous calcium silicate hydrate (C-S-H). The obtained results indicate that 5% MP in air-cured cement -based materials exhibited the best behavior with acceptable resistance to acid attacks. This level of MP replacement was found to optimize the filler effect, improve the hydration process, and enhance the matrix density, which in turn reduces the permeability of the material and increases acid resistance. This is attributed to the balanced contribution of MP to phase formation, particularly calcite, which helps to counteract acid-induced dissolution, while also preserving the stability of C-S-H phases. This study provides a new perspective of the role of MP in influencing phase content (crystalline and amorphous phases) and their possible impacts on macroscopic properties such as apparent density and compressive strength. MP behaved as a filler, to improve hydration and resistance to acid attacks. Additionally, using MP as a replacement for ordinary Portland cement (OPC) offers a sustainable alternative by reducing waste and promoting the recycling of marble industry by-products, thereby contributing to environmental sustainability. It is recommended that, 5% MP is the optimal replacement content to enhance durability and mechanical properties in air-cured cement-based materials in aggressive environments, as it is both practical and achievable for infrastructure to be subjected to the aggressive environment. Full article

Economic and technological factors necessitate the use of alternative fuels during oil shale combustion, a process that generates substantial amounts of solid waste with varying ash compositions. This study evaluates the potential of two such waste materials: (i) fly ash derived from the combustion of oil shale (a fine particulate residue from burning crushed shale rock, sometimes combined with biomass), and (ii) short carbon fibres recovered from the pyrolysis (a process of decomposing materials at high temperatures in the absence of oxygen) of waste wind turbine blades. Oil shale ash from two different sources was investigated as a partial cement replacement, while recycled short carbon fibres (rCFs) were incorporated to enhance the functional properties of mortar composites. Results showed that carbonate-rich ash promoted the formation of higher amounts of monocarboaluminate (a crystalline hydration product in cement chemistry), leading to a refined pore structure and increased volumes of reaction products—primarily calcium silicate hydrates (C–S–H, critical compounds for cement strength). The findings indicate that the mineralogical composition of the modified binder (the mixture that holds solid particles together in mortar), rather than the fibre content, is the dominant factor in achieving a dense microstructure. This, in turn, enhances resistance to water ingress and improves mechanical performance under long-term hydration and freeze–thaw exposure. Life cycle assessment (LCA, a method to evaluate environmental impacts across a product’s lifespan) further demonstrated that combining complex binders with rCFs can significantly reduce the environmental impacts of cement production, particularly in terms of global warming potential (−4225 kg CO₂ eq), terrestrial ecotoxicity (−1651 kg 1,4-DCB), human non-carcinogenic toxicity (−2280 kg 1,4-DCB), and fossil resource scarcity (−422 kg oil eq). Overall, the integrative use of OSA and rCF presents a sustainable alternative to conventional cement, aligning with principles of waste recovery and reuse, while providing a foundation for the development of next-generation binder systems. Full article

Semi-Flexible Pavement (SFP) combines the flexibility of asphalt concrete and the rigidity of cement concrete to provide excellent high-temperature rutting resistance in the summer. However, its application is often limited by the fluidity and mechanical properties of cement-based grouting materials. This study systematically optimized the mix ratios of three types of grouting materials (cement-based, mineral-modified, and polymer-enhanced) using response surface methodology combined with orthogonal tests. The effects of water–binder ratio (W/B), sand–binder ratio (S/B), mineral admixtures and polymer additives on the key properties of grouting materials were systematically studied. By using Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD), the evolution of the mixture microstructure and the mechanism of performance change were also analyzed. The test results show that the optimal mix ratio of the cement-based grouting material is W/B = 0.46 and S/B = 0.15; the optimal mix ratio of the mineral grouting material is to replace part of the cement with fly ash (9%), silica fume (6%) and microspheres (3%). Microscopic tests show that fly ash effectively inhibits bleeding; silica fume and fly ash promote the formation of calcium silicate hydrate (C-S-H) gel; microspheres optimize the rheology of the slurry; and the synergistic effect of silica fume and microspheres reduces the internal pores of the grouting material, achieving high fluidity, low bleeding rate and excellent mechanical properties of the grouting material. The polymer-reinforced grouting material is an enhanced slurry formed by adding high-performance water reducer (0.8%), rubber powder (2%) and coupling agent (0.9%) to the optimal mineral grouting material. The combined effect of rubber powder and coupling agent significantly improves the adhesive property between the grouting material and the asphalt interface, making it more suitable for the road performance of SFP in low-temperature environments. Full article

This study presents an analytical and multiscale investigation of the degradation of elastic properties in ordinary Portland cement (OPC) paste subjected to calcium leaching. Eight representative microstructures and three homogenization schemes (Mori–Tanaka, Hashin–Shtrikman, and Voigt) were evaluated to determine the most suitable configuration for predicting stiffness evolution. Model validation against benchmark experimental data at 14 and 56 days demonstrated good agreement, with prediction errors within 10%. Simulation results reveal that progressive decalcification leads to significant reductions in both bulk and shear moduli, with the calcium hydroxide (CH) phase being the most sensitive, followed by low-density (LD) and high-density (HD) calcium silicate hydrate (CSH). The overall stiffness loss increases with the water-to-cement ratio ($w/c$), exceeding 90% at $w/c=0.5$ under complete decalcification. A sensitivity analysis further shows that the rate of modulus degradation decreases with increasing $w/c$, reflecting a mechanical normalization effect rather than improved chemical stability. These findings highlight the dominant role of calcium preservation in maintaining mechanical integrity and provide a robust theoretical framework for predicting the chemo-mechanical degradation and long-term durability of cement-based materials in aggressive environments. Full article

Calcium silicate-based cement is commonly used for bone repair and regeneration. Current research focuses on developing innovative antibacterial materials with radiopacity, which is essential for ensuring successful clinical outcomes in procedures like vertebroplasty and endodontic treatments. Strontium (Sr) has emerged as a powerful additive, stimulating bone formation and inhibiting bone resorption. In this study, we evaluated the impact of varying levels of Sr—5, 10, and 20 mol% (designated as CSSr5, CSSr10, and CSSr20) on critical attributes of bone cement, including radiopacity, setting time, in vitro bioactivity, antibacterial efficacy, and osteogenic activity. The findings indicated that as the Sr content increased, the setting time and radiopacity of the cement increased. Remarkably, the cement formulations containing over 10 mol% Sr achieved radiopacity values surpassing the 3 mm aluminum threshold mandated by ISO 6876:2001 standards. Furthermore, incorporating Sr significantly improved MG63 cell attachment, proliferation, differentiation, and mineralization, while also boosting antibacterial properties in a dose-dependent manner. After 48 h of inoculation with E. coli or S. aureus, the CSSr10 and CSSr20 cements showed a bacteriostatic ratio exceeding 1.7 or 2 times that of the control without Sr. In conclusion, the CSSr10 cement could be a promising bone filler, exhibiting favorable setting time, radiopacity, antibacterial ability, and osteogenic activity. Full article

Background: The bonding compatibility between calcium silicate-based bioceramic cements and restorative materials is critical for long-term success in pediatric dentistry. This study compared the shear bond strength (SBS) of contemporary biointeractive restorative materials to two widely used bioceramics, NeoMTA Plus (NM) and Biodentine (BD). Methods: Eighty acrylic resin blocks with standardized cavities were filled with either NM or BD (n = 40 each) and subdivided into four restorative groups: nanohybrid composite (Filtek Ultimate), giomer (Beautifil II), bioactive restorative (Activa BioActive Restorative), and high-viscosity glass ionomer cement (Fuji IX GP Extra) (n = 10 each). All restorations followed a standardized etch-and-bond protocol. SBS was measured using a universal testing machine, and failure modes were assessed under a stereomicroscope. Data were analyzed using one-way ANOVA and Tukey’s HSD (p < 0.05). Results: BD exhibited significantly higher SBS values than NM (p < 0.001). In the BD group, Filtek Ultimate and Beautifil II achieved the highest and statistically comparable SBS, outperforming Activa BioActive Restorative and Fuji IX GP Extra (p < 0.05). In the NM group, no significant differences were found among materials. Adhesive failures predominated in NM (85%), while BD showed more cohesive failures (50%). Conclusions: Biodentine demonstrated superior bonding stability to restorative materials, with composite resin and giomer performing best. Giomer’s bioactivity and ion release make it a viable alternative to composite resin in suitable clinical contexts. Full article

This study aims to develop a high-performance grouting material for mine goaf backfilling, creating a green and low-carbon cementitious alternative by utilizing coal gangue and sludge as the primary precursors. Based on an orthogonal experimental design, the effects of four factors including the coal gangue/sludge ratio, activator modulus, water–binder ratio, and sodium-to-aluminum ratio on the compressive strength of the geopolymer were systematically investigated. The mineral composition and microstructure of the geopolymer were analyzed using microscopic test methods such as XRD and SEM. The test results indicate that the water–binder ratio has the most significant effect on the polymerization performance of the coal gangue/sludge-based geopolymer (CSG), with compressive strength increasing as the water–binder ratio decreases. The Ca²⁺ provided by the sludge to the reaction system directly promotes the formation of new calcium-containing products such as anorthite and calcium silicate hydrate, which play an important role in improving the strength of geopolymers. Moreover, the developed CSG exhibits a significantly lower carbon footprint compared to conventional cement-based grouting materials, aligning with the goals of sustainable and green construction. When the coal gangue/sludge ratio is 7:3, the water–binder ratio is 0.3, the sodium-to-aluminum ratio is 0.64, and the activator modulus is 1.0, the 3-day compressive strength (CS) of the geopolymer reaches 34.5 MPa, demonstrating its potential as an effective and environmentally friendly grouting material for goaf applications. Full article

The long-term stability of bioactive dental cements in acidic environments is not yet fully understood, despite their extensive clinical use in restorative and endodontic procedures. The objective of this study is to evaluate the degradation behaviour and mechanical stability of one glass ionomer cement (GC FUJI IX^®) and two calcium-silicate-based materials (Biodentine^® and Biodentine XP 500^®) under simulated acidic oral conditions. A total of 18 samples were prepared and distributed into three groups. The materials were immersed in a solution with a pH of 4.5, and their performance was assessed through a number of different methods. These included mass-loss measurements, corrosion-rate calculations, Vickers microhardness testing, and SEM to characterise the surfaces. Biodentine^® exhibited the highest degradation, followed by Bio-Dentine XP 500^® and GC FUJI IX^®. The data were confirmed by one-way ANOVA and a post hoc Tukey’s test. This indicated a statistically significant superiority (p < 0.05) of Biodentine XP 500^® over glass ionomers in terms of surface hardness maintenance under acidic conditions. Biodentine^®, a calcium silicate-based material, demonstrated inferior chemical stability compared to GC FUJI IX^® and Biodentine XP 500^®, likely due to its modified calcium-silicate formulation that limits ionic dissolution. In addition, the study revealed that Biodentine XP 500^® exhibited the highest Vickers hardness under acidic conditions. The findings reported in this study offer valuable insights into the material selection process for low-pH clinical scenarios and contribute to a more comprehensive understanding of the chemical–mechanical stability of modern bioactive dental restoratives. Full article

Grouting materials can be used for reinforcement and water plugging of underground engineering in sandy strata. This study examines the mechanism of alkali-activated cementitious materials by selecting steel slag and ground slag to replace cement in double-liquid grouting materials. Various retarders were used to adjust the gel time, making it controllable for grouting materials. The results show that when the sodium silicate volume is in the range of 20–40%, the W/B is in the range of 0.7–1.0, and the steel-slag-to-ground-slag ratio (SS:SL) is 3:7, the macroscopic properties of the grouting material reach the optimal value, the microstructure is denser, and the hydration products are calcium hydroxide, calcium–silicate–hydrate (C-S-H) gel, and ettringite. When the cement content is 40%, the W/B is 0.8, the sodium silicate volume dosage is 30%, and the SS:SL ratio is 3:7, the 3 d compressive strength of the slurry reaches 14.57 MPa and the 28 d compressive strength reaches 21.14 MPa. To analyse the solidification effect of double-liquid grouting materials with mixed SS and SL on sandy soil, experiments were conducted to study the impacts of the soil moisture content, soil particle size distribution, and slurry quantity on the strength of consolidation. This study conducts an in-depth investigation into optimising the proportioning of industrial solid wastes and the multi-component synergistic mechanisms. This study provides a new method for the effective utilisation of industrial waste and a reference for the practical application of industrial waste as supplementary cementitious materials in the future. Full article

Silica fume (SF) is extensively utilized for enhancing concrete properties. This study examines the impact of SF dosage on concrete frost resistance. Specimens were produced by replacing cement with SF at 5%, 10%, 20%, and 30% ratios. Mechanical testing and microscopic characterization measured variations in mass loss, relative dynamic elastic modulus, flexural strength, hydration products, and pore structure. Digital image correlation tracked failure development during flexural tests. Results indicated that SF-modified concrete showed lower mass loss, better elastic modulus retention, and improved flexural strength maintenance compared to plain concrete after identical freeze–thaw (F-T) cycles. Additionally, SF-modified concrete demonstrated reduced crack widths and slower crack expansion during bending. The 10% SF mixture, after 300 cycles, achieved optimal results characterized by 2.83% mass loss, 88.1% relative dynamic modulus, and only a 17% flexural strength reduction. Microscopic studies confirm that SF addition increases calcium silicate hydrate formation, decreases calcium hydroxide levels, and refines pore structure with higher density. These modifications enhance frost resistance. A service-life prediction model using gray model approach methodology projected that 10% SF concrete would last 2.01 times longer than unmodified concrete under F-T exposure. Full article