Calcium Silicate Research Articles

Stabilization and Solidification of Beryllium Waste: Influence of the Cement Composition on the Corrosion of Be Metal

Beryllium metal is used as neutron moderator and reflector or multiplier in certain types of fission or fusion reactors. Dismantling of these reactors will produce radioactive beryllium waste, classified as low- or intermediate-level waste, that will need to be stabilised and solidified before being sent to disposal. The cementation process is under consideration because it may offer a good compromise between simplicity of implementation, cost, and quality of the final cemented wasteform. Nevertheless, knowledge of the corrosion behaviour of Be metal in a cement-based matrix is still limited, partly due to the high toxicity of Be that complicates testing. This study thus investigates Be corrosion in cement suspensions using potentiometry, voltammetry, and electrochemical impedance spectroscopy. Among the five different investigated systems (Portland cement blended without or with 40 wt.% silica fume, calcium sulfoaluminate clinker blended without or with 15% anhydrite, and calcium aluminate cement), Portland cement blended with 40% silica fume and calcium sulfoaluminate cement comprising 15% anhydrite are the most effective in mitigating beryllium corrosion. They allow reduction in the corrosion current by factors of 4 and 50, respectively, as compared to Portland cement.

Study on Phase Evolution of Calcium Silicate Hydrate (C-S-H) During Solidification of Cr(VI) under Hydrothermal Conditions

In this paper, calcium silicate hydrate (C-S-H) was synthesized by hydrothermal method using CaO and quartz sand as raw materials. The solidification effect of Cr(Ⅵ) in C-S-H was studied using XRD, FTIR, and SEM. The leaching amount of Cr(Ⅵ) after solidification was determined by anatomic absorption spectrometer to analyze and calculate the solidification rate of Cr(Ⅵ). Results show that appropriately increasing the reaction temperature and prolonging the reaction time can help improve the crystallinity of C-S-H. A small Cr(Ⅵ) dosage of Cr/Si < 0.05 is beneficial for the crystallization of C-S-H, but when Cr/Si > 1.0, Cr(Ⅵ) ions inhibit the formation of C-S-H. When Cr/Si <0.15, the solidification efficiency of C-S-H on Cr(Ⅵ) decreases with increasing Cr(Ⅵ) content; The C-S-H with Ca/Si = 1 has the best solidification efficiency for Cr(Ⅵ).

Consolidation Enhancement of Weathered Coal Gangue Utilized for Aggregate Filling of Cement Pavement in Mining Area

The large-scale, open-air storage of coal gangue often leads to oxidation and decomposition due to natural weathering, resulting in decreased strength and instability, which limits its wider application in concrete pavement. To address these issues, this paper proposed a composite consolidation treatment for weathered coal gangue (WCG), assessing its effectiveness and enhancement mechanisms through aggregate performance tests, mixture performance tests, and microscopic visualization analyses. Results indicated that the initial and post-20 dry–wet cycle crushing values of WCG were 23.96% and 47.94%, respectively, failing to meet required standards. However, applying a composite consolidation treatment using a lithium curing agent and cement paste significantly improved WCG’s robustness and stability. After 4 days of treatment, the crushing value, impact value, and Vickers hardness of WCG had reached 18.3%, 6.58%, and 113.52 kgf/mm², respectively, fully meeting the standards for aggregate filling in mini concrete pavements. Furthermore, tests demonstrated that the lithium curing agent induced the formation of hydrated calcium silicate and calcium aluminate on both the surface and interior of the WCG, enhancing its structural stability. Approximately 5–12 wt.% of the curing agent penetrates and encapsulates the WCG, strongly bonding and reinforcing its internal weak surfaces. These findings offer potential solutions and technical insights for the large-scale management of weathered coal gangue.

Non-Surgical Endodontic Management of Large Periapical Lesions After Traumatic Dental Injuries.

Traumatic dental injuries of permanent teeth result in multiple immediate and long-term consequences depending upon the severity of trauma, age of the patient, the status of root maturity, and the emergency care provided. The healing responses may get disturbed due to severe damage, loss of vascularity of the supporting structures, and infections. As a result, the prohealing mediators and pathways are overpowered by the destructive stimuli often manifested by an increased osteoclastic activity. Among the various late complications, the apical periodontitis or the periapical lesions are most worrisome for the patients and create clinical dilemma for the dentists. In the past, many such lesions were classified as cysts and subjected to surgical management. However, better understanding of lesion pathophysiology, three-dimensional imaging, and molecular pathways have established their inflammatory nature. The advancements in materials such as calcium silicates, and regenerative techniques have propelled the research related to non-surgical endodontic management as its clinical acceptability. The treatment largely follows the recommendations of regenerative medicine and is based on four principles: (a) establishing the drainage or an endodontic access to the area, (b) removal of most of the triggering agents such as necrosed pulp, toxins, and inflammatory mediators, (c) disinfection of the area, controlling inflammation and reversal of the acidic pH, and (d) maintenance of this infection/inflammation-free state for a long time through adequate sealing. This review aims to highlight the rationale of the approach, case selection, pathophysiology of the causation and healing, clinical protocols, and the limitations of non-surgical endodontic management of large periapical lesions secondary to traumatic dental injuries.

Self-healing performance of silica nanoparticle-infused concrete based on microbial mineralization

This study investigates the effects of incorporating two substances–expanded perlite as a carrier for bacteria and nanosilica–into cement mortar. The objective of this study is to evaluate the effect of the dosage of these two substances on the strength and self-healing properties of mortars. The strengths of the specimens at different curing ages are tested using a pressure-testing machine and recorded. Additionally, precracks are introduced into the specimens. The cracks and their healing products are observed via electron microscopy, scanning electron microscopy, and X-ray diffraction to validate the experimental results. The results show that the self-healing agents agglomerate at the cracks and trigger a metabolic reaction, thus resulting in the formation of numerous calcium carbonate precipitates that sealed the cracks. Therefore, the addition of self-healing agents significantly improves the self-healing properties of the cement mortar. The nanosilica facilitates the hydration reaction of cement in mortar. Additionally, nanosilica undergoes a pozzolanic reaction with calcium hydroxide, which consumes calcium hydroxide and generates hydrated calcium silicate to fill the pores. Consequently, the incorporation of an appropriate amount of nanosilica effectively enhances the strength of the cement mortar. Therefore, simultaneously incorporating self-healing agents and nanosilica while controlling the dosage provides a new approach for optimizing both the mechanical properties and self-healing performance of concrete.

Unveiling the Impact of Absorbent Polymers on Self-healing Efficiency of Sludge-derived Capsules in Cementitious Composites

A novel green capsule for self-healing cementitious material using a combination of waste-based materials with an inorganic substance was developed. A mix of alum sludge (AS), a typical waste from the water industry, and calcium hydroxide were used as the primary healing agents. Also, two types of natural and synthetic absorbent polymers (AP), microcrystalline cellulose (MCC) and sodium polyacrylate (SPA), were added to the core mixture to assess their impact on the healing efficiency. The morphology of the produced capsules, the self-healing proficiency of cracked mortars, and the resulting healing materials were characterised. Outcomes revealed that cracks up to 400µm could be healed by the plain capsule. The closure width was dramatically increased to 500µm and 800µm with the inclusion of MCC and SPA, respectively, mainly in 3 days. The expansion, water retention, and bridging properties of the APs enhanced the sealing performance of the capsules by providing nucleation sites and increasing the reaction rates of core materials to generate further calcium-based products inside the cracks. Therefore, higher recovery rates of mechanical strengths, along with a significant reduction in water ingress were achieved. The main healing products were identified as calcite crystals, C-S-H, calcium silicate, and aluminium-bearing phases.

Fluidized solidified soil using construction slurry improved by fly ash and slag: preparation, mechanical property, and microstructure

Abstract Fluidized solidified soil (FSS) is a cement-based engineering matergood working performance and mechanical properties. Based on fixed cement and desulphurisation gypsum (DG), fly ash (FA) and ground granulated blast furnace slag (GGBS) were added as admixtures to the construction slurry to prepare three types of FSS: namely cement-GGBS-DG FSS (CGD-FSS), cement-FA-GGBS-DG FSS (CFGD-FSS), and cement-FA-DG FSS (CFD-FSS). Considering 7 d, 14 d, and 28 d three curing times, compressive, flexural, scanning electron microscopy (SEM), and x-ray diffraction (XRD) analyses were conducted to explore the time-dependent mechanical properties and microscopic characterisation of FSS. The mechanical test showed that CFGD-FSS doped with FA and GGBS had better fluidity, compressive strength, and flexural strength than CGD-FSS doped with FA alone and CFD-FSS doped with GGBS. The CFGD-FSS specimen with a cement:FA:GGBS:DG ratio of 30: 10: 40: 20 in the curing agent had the best mechanical properties, i.e., the CFGD01 specimens. It has fluidity of 189 mm, compressive strength of 671 kPa, and flexural strength of 221 kPa with a 28d curing time, which can meet the working requirements of FSS for filling narrow engineering spaces. And compared with other specimens, it has the shortest setting time, which can effectively shorten the construction period. Microscopic analysis showed that a large number of hydration products, such as calcium silicate hydrate, calcium aluminate hydrate, and ettringite (Aft), were well-formed in the FSS, resulting in good mechanical properties, especially for the CFGD-01 specimens. Finally, two empirical models were established to describe the compressive strength–porosity and flexural strength–porosity relationships. Moreover, the investigated data agreed well with the modelling results.

Study of the Structure and Properties of Concrete Modified with Nanofibrils and Nanospheres

The application of modifying nanoadditives in the technology of cement composites is currently a relevant and widely researched topic in global materials science. The purpose of this study was to investigate new nanoadditives—nanofibrils made from synthesized wollastonite (NF) and nanospheres from corundum (NS)—produced by LLC NPK Nanosystems (Rostov-on-Don, Russia) as a modifying additive. During the experimental investigations, the mechanical properties of cement pastes and concrete were examined. This included an analysis of the density, compressive and bending strength, as well as water absorption of concrete that had been modified with NF and NS additives. X-ray phase and microstructural analyses of concrete were performed. It was established that modification of cement composites with NF and NS additives had a beneficial effect on their properties, and the optimal amount for both types of additives was 0.3% by binder weight. The highest recorded enhancements in compressive and flexural strength of concrete with 0.3% NF were 7.22% and 7.04%, respectively, accompanied by a decrease in water absorption by 4.70%. When modifying concrete with 0.3% NS, the increases in compressive and flexural strength were 2.71% and 2.48%, and water absorption decreased by 1.96%. Modification of concrete with NF and NS additives did not have a significant effect on the change in concrete density, which was no more than 1%. Based on the results of phase analysis, it was established that concrete with NF and NS additives were characterized by the presence of five main phases: quartz, portlandite, calcite, larnite, and olivine-Ca. It was found that compositions with 0.3% NF and NS differed from the control composition by the presence of such a phase as olivine-Ca. Microstructural analysis confirmed the effectiveness of NF and NS additives. The microstructure of the modified concretes was distinguished by the extensive occurrence of clusters composed of calcium silicate hydrate zones. The conducted studies prove the possibility of using NF and NS as modifying nanoadditives in the technology of cement composites. The addition of nanofibrils from synthesized wollastonite is the most effective and promising and is recommended for use in real construction practice.

Calcium Silicate Promoting the Upcycling Potential of Polysulfone Medical Waste in Load-Bearing Applications

Polysulfone (PSF) medical waste can be effectively repurposed due to its excellent mechanical properties. Due to the increasing need for load-bearing bone implants, it is crucial to prioritize the development of biocompatible polymer–matrix composites. Calcium silicate (CaSi), known for its osteogenesis and antibacterial properties, is widely used in medical applications. In this study, recycled PSF plastics in fiber or nanoparticle forms and commercial PSF products were used to create PSF-based composites filled with three different amounts (10, 20, and 30 vol%) of CaSi. The green compact was heat-treated at various temperatures. Experimental results showed that the mechanical interlocking of the PSF matrix and CaSi filler occurred due to the liquefaction of PSF fibers or nanoparticles during heat treatment. When the composite contained 20% CaSi, the obtained three-point bending strength exceeded 60 MPa, falling within the reported strength of compact bone. There was a concurrent improvement in the biocompatibility and antibacterial activity of the PSF-based composites with the increasing amount of CaSi. Considering their mechanical properties and antibacterial activity, the 20% CaSi-containing PSF-based composites treated at 240 °C emerged as a promising candidate for bone implant applications. This study demonstrated the feasibility of upcycling medical waste such as PSF as a matrix, opening doors for its potential usage in the medical field.

Deep caries and pulp exposures management preferences in permanent teeth: A survey amongst Spanish dentists.

To assess Spanish dentists' management preferences for deep caries removal and exposed pulps in permanent teeth. A web-based open and anonymous survey was distributed by social media and a specific website for this project amongst dentists practicing in Spain. The questionnaire comprised 40 questions, divided into five sections: (1) demographic data and professional activity; (2) carious tissue removal; (3) decision-making regarding pulp exposure; (4) direct pulp capping and (5) pulpotomy procedures in permanent teeth. Results were descriptively analysed. Logistic regression (95% CI) analyses and X2 tests were carried out. A total of 538 responses were received. Half the respondents (53.7%) preferred to perform complete caries excavation for shallow and moderate carious dentin lesions, and selective excavation to firm dentin for deep lesions (57.8%). Selective removal to soft dentin and stepwise removal were much less indicated (15.4% and 10.9%, respectively). Exposed pulps in asymptomatic teeth were treated by direct pulp capping (over 80%), decreasing in the presence of reversible pulpitis symptoms (57.1%). If irreversible pulpitis was diagnosed, a pulpectomy would be performed by 53.5% and 89.9% of the respondents in, respectively, immature and mature teeth. Pulpotomy was performed routinely only by 26.4% of the clinicians. Patients' attitudes and priorities were the most relevant criteria when performing direct pulp capping and pulpotomy, together with the history of pain and the presence of bleeding. Regarding the clinical procedure, dry cotton was preferred to obtain haemostasis and Biodentine was the material of election. Caries removal preferences and management of pulp exposure by dentists practicing in Spain deviated from vital pulp treatment guidelines, mainly regarding indications and case selection. Pulp exposure was managed by direct pulp capping in asymptomatic cases, whilst immature permanent molars favoured the indication of pulpotomy when pulpitis was diagnosed. Most clinicians used hydraulic calcium silicate cement, specifically Biodentine, to perform vital pulp treatments. Postgraduate formation and continuing education in caries lesions management and vital pulp treatments were consistently related to more conservative and updated decisions.

Production of Autoclaved Cementitious Composites Using Recycled Waste Glass

ABSTRACTOne of the major negative environmental implications of economic growth and the advancement of information technology is the large quantity of electronic waste dumped in landfills. Cathode ray tubes (CRTs) from outdated televisions and computer monitors are a significant source of electrical waste. The CRT funnel primarily consists of silica, significant alkalis (Na2O‐K2O), and heavy metals like barium‐strontium, along with a substantial lead (Pb) content that may contaminate the soil. Owing to its heavy metal content, CRT is considered hazardous waste, and regulations require its glass to be recycled or repurposed instead of landfill disposal. The low pozzolanic activity of CRT silica suggests that its high content, when paired with an optimized particle size and specific curing conditions, can enhance the mechanical properties of cement‐based products. Hydrothermal treatment has been found to speed up both the hydration of ordinary Portland cement (OPC) and the pozzolanic reactions. Since the main objective was to safely recycle large amounts of CRT, three mixes were proposed with 10%, 20%, and 30% OPC + 90%, 80%, and 70% CRT, respectively, and the effect of hydrothermal curing conditions on mechanical properties and durability of these blends was investigated. CRT‐70, a blend containing 70% CRT glass waste, showed enhanced strength due to the formation of zeolitic phases and calcium silicate hydrate (CSH). These phases also provided CRT‐70 with notable fire resistance, ensuring its structural stability under elevated temperatures. These results demonstrate the possibility of production of precast building products via high‐volume recycling of hazardous CRT waste.

Root-filling materials for endodontic surgery: biological and clinical aspects

The placement of root filling materials aims to prevent the occurrence of post-treatment apical periodontitis following completion of endodontic treatment. Materials should possess properties that will not permit bacterial invasion and infection, namely excellent sealing ability and/or antibacterial properties. In root-end filling procedures or repair of root perforations, the root filling materials are placed in a particularly challenging clinical environment, as they interface with a relatively large area with the periradicular tissues. The biological properties of these materials are therefore of significant importance. The current review discusses the most widely used materials for endodontic surgery (i.e., root-end filling and perforation repair), with particular focus on their biological characteristics, namely antibacterial properties and interactions with host tissue cells, together with clinical studies. Properties of amalgam, glass ionomer cements (GICs), resin systems, zinc oxide eugenol-based cements and hydraulic calcium silicate cements (HCSCs), together with representative and well-researched commercial materials in the context of their use in endodontic surgery are presented. While the use of HCSCs seems to offer several biological advantages, together with addressing issues with the initial formulation in the most recent versions, materials with different chemical compositions, such as zinc oxide eugenol-based cements, are still in use and appear to provide similar clinical success rates to HCSCs. Thus, the significance of the currently available materials on clinical outcomes remains unclear.

Role of Ti3AlC2 MAX phase in regulating biodegradation and improving electrical properties of calcium silicate ceramic for bone repair applications

Calcium silicate ceramic is a promising bioceramic for various biomedical applications, but its high biodegradation rate and low strength restrict its clinical utility. As a result, the study devised an innovative solution to address these issues by utilizing the titanium aluminum carbide phase, potentially for the first time in biological applications, in conjugation with hydroxyapatite. Then, using powder metallurgy technology, they added these phases to calcium silicate to create nanocomposites. After soaking in simulated body fluid for ten days, the produced nanocomposites were assessed for bioactivity and biodegradability using scanning electron microscopy, inductively coupled plasma-atomic emission spectroscopy, and weight loss assays. Their electrical and dielectric properties were also measured before and after soaking in the simulated body fluid solution. Furthermore, the tribo-mechanical properties of all sintered samples were measured. Interestingly, adding 40% hydroxyapatite nanoparticles to calcium silicate reduced the porosity from 12 to 6%. However, adding five vol% of the titanium aluminum carbide phase to the same sample increased the porosity to 8%. Importantly, these recorded percentages of porosity were comparable to those of compact bone porosity, which range from 5 to 13%. The addition of hydroxyapatite and titanium aluminum carbide phase significantly improved the rapid biodegradation of calcium silicate, albeit with a slight decrease in its bioactive properties, as evidenced by the incomplete surface coverage of the samples with the hydroxyapatite layer in the scanning electron microscopy images. The electrical properties of the nanocomposites were better with the addition of hydroxyapatite and titanium aluminum carbide phase, which helped the bone heal faster. The addition of a titanium aluminum carbide phase significantly improved the mechanical properties of the resulting nanocomposites. For example, the calculated values for compressive strength of all examined samples were 131, 115, 105, 147, and 135 MPa. Based on the results, the prepared samples can be used in orthopaedic and dental applications.

Degradation of Concrete Cement Stone Under the Influence of Aspergillus niger Fungi

The concepts of physical and chemical transformations occurring in cement concrete under conditions of microbiological deterioration can be used to control the processes of the destruction of cement concretes in order to ensure the required durability and to predict the service life of products. The study of changes in the structural and phase composition of cement stone made of Portland cement grade CEM I 42.5N in the process of fungal deterioration for 6 months when moistened, as well as a sample of a concrete wall exposed to fungal microorganisms for 20 years, was carried out. Diffractograms of the studied cement stone samples contain a large number of pronounced narrow peaks and indicate a highly crystalline structure of phases with the presence of an X-ray amorphous phase of calcium hydrosilicates and tobermorite gel in the cement stone. Changes in the structure of cement stone under the influence of fungi are confirmed by the data of a derivatographic analysis. A decrease in the content of calcium hydrosilicates and ettringite, as well as other crystalline phases in cement stone, leads to a decrease in compressive strength by about 15% over 6 months of fungal degradation. Similar changes after 20 years of exposure to microorganisms suggest deterioration in the strength characteristics of concrete.

Impact of Acidic and Alkaline Environments on the Surface Morphology of Biodentine and White Mineral Trioxide Aggregate - An In-vitro Study.

The physical and chemical properties of calcium silicate cement might be affected due to exposure to acidic or alkaline conditions during clinical use. The present study aimed to evaluate the effect of acidic and alkaline environments on the surface morphology of biodentine (BD) and white mineral trioxide aggregate (wMTA). Disc-shaped specimens of BD (n = 30) and wMTA (n = 30) were prepared in a metal mould and wrapped in pieces of gauze. They were divided into three sub-groups according to the storage media: group A, soaked in sterile distilled water at a pH of 7.0; group B, exposed to butyric acid buffered at pH 4.0; and group C, exposed to calcium hydroxide solution buffered at pH 12.0. The specimens were incubated for 7 days at 37°C, followed by examination under scanning electron microscopy at 1000x and 5000x magnification to characterise the microstructural morphology. Definite changes were seen in the microstructure of BD and wMTA on exposure to acidic and alkaline pH. The microstructure of wMTA tends to exhibit reduced cohesion when exposed to an acidic environment, especially when compared to an alkaline pH. Acidic pH exerts a milder influence on the morphological structure of BD when contrasted with its effects on wMTA. Biodentine may emerge as a more prudent choice than wMTA for utilisation in inflamed periapical regions.

Bond strength of resin-based restorative materials to fast-setting calcium silicate cement using different resin adhesive systems.

This study assessed the bond strength of resin-based restorative materials to fast-setting calcium silicate cement (Aarhus Uinversity, Denmark) when treated with each of two one-bottle universal adhesive systems. The cement surface (N=256) was treated with a self-priming adhesive and a self-etch phosphate monomer-containing adhesive with and without etching of the cement surface. Specimens then received either resin composite or compomer restorative materials (n=32). The bond strength was measured after 1 day and 1500 thermocycles (n=16). The failure type was visually inspected. The cement-adhesive-restorative material interface was visualized using scanning electron microscopy (SEM). The data were analyzed using multiple linear regression. Restorative material type, resin adhesive system, and thermocycling had a statistically significant effect on the bond strength. Compomer restorative material and self-etch universal adhesive system demonstrated statistically significantly higher bond strength values to fast-setting calcium silicate cement, predominantly exhibiting cement cohesive failure. Etching the cement surface enhanced the bond strength of the self-priming universal adhesive. Thermocycling significantly reduced the bond strength. SEM showed self-etch universal adhesive seemingly diffused over the etched cement surface compared to other groups. Self-etch phosphate monomer-containing universal adhesive and compomer resulted in the highest bond strength to fast-setting calcium silicate cement.

Preparation of C-S-H seeds from waste glass powder and its effect on early performance of cement paste

This study investigates the hydrothermal synthesis of calcium silicate hydrate (C-S-H) seeds using nano-size glass powder (NGP) derived from siliceous raw materials and CaO as the calcareous precursor. The influence of varying NGP concentrations on the particle size, microstructure, and phase composition of the C-S-H seeds was systematically analyzed. The synthesized C-S-H seeds were subsequently employed as additives to evaluate their effects on the early hydration process and compressive strength development of cement paste. The results indicate that increasing the NGP concentration from 0.2 mol/L to 0.8 mol/L leads to an exponential increase in the median particle size of the C-S-H seeds from 147 nm to 1328 nm and a corresponding morphological transformation from flocculent to granular structures. Additionally, the purity of the C-S-H sample decreased from 74.8% to 54.5% as the NGP concentration increased. The addition of C-S-H seeds can increase the 12h compressive strength of cement pastes by 15.5%–53.5%. This improvement is due to the accelerated early hydration kinetics induced by the C-S-H seeds, which act as nucleation sites, thereby increasing the nucleation and growth rates by 31.4% and 53.2%, respectively.

Fiber post cemented using different adhesive strategies to root canal dentin obturated with calcium silicate-based sealer

BackgroundCalcium silicate-based sealer has favorable properties for root canal filling, including hydroxyapatite formation during the setting process. However, this process can cause difficulty during post space preparation when the sealer is set. Additionally, the remaining sealer could interfere with the bond strength of fiber post to root canal dentin. The different adhesive strategies and fiber post cementation time may affect the bond strength of the fiber post. Thus, the objective of this study was to evaluate the effect of etching modes of Scotchbond™ Universal Plus adhesive and post cementation time on the push-out bond strength of a fiber post cemented in root canals obturated with calcium silicate-based sealer.MethodsFifty-four teeth were randomly allocated to 6 groups (n = 9) based on etching modes: self-etch (SE) or etch-and-rinse (ER); post space preparation and cementation time: immediate (Im) or 7-day delayed (De): Im-Im, Im-De, and De-De. The root canals were obturated with calcium silicate-based sealer and the post space preparation was performed. The fiber post was cemented using RelyX™ Universal resin cement according to each group’s design. For the push-out bond strength test, 1-mm slices of the coronal, middle, and apical regions were tested using a universal testing machine. The failure mode analysis was determined using a stereomicroscope. The data was analyzed with three-way analysis of variance.ResultsNo negative effects of etching modes, post space preparation or cementation time on push-out bond strength were detected (p > 0.05). Additionally, the root canal region also did not significantly affect the bond strength (p > 0.05).ConclusionNo significant differences were observed between the etching modes, post space preparation and cementation time and among root canal regions.Clinical relevanceThe different etching modes of adhesive and post cementation time did not affect the bond strength of fiber post in calcium silicate filled-root canal.

Investigation on Key Influencing Factors Affecting Temperature Distribution in Concrete

Concrete is an unavoidable composite material used in buildings and structures. The behavior of concrete under the effect of fire is always critical, causing more structural damage. This research proposes experimental investigation on various factors that affect temperature distribution in concrete when exposed to fire. Water cement ratio, grade of concrete, curing period, type of admixtures, and fibers are the factors taken into consideration. The test was carried out in the temperature range of 100 °C to 600 °C. The temperature was measured at various depths of the specimen and then compared. Results from experiments show that grade of concrete, water-cement ratio, curing period and admixture type significantly influences the temperature distribution in concrete whereas contribution of fiber type is negligible. Comparison of temperature distribution at 25 mm from the bottom of specimen at 600 °C for M20 grade with 0.5 and 0.4 water cement ratio was done. It is found that temperature distribution in concrete goes higher as water cement ratio goes higher. There is an increase of 22.6% of temperature distribution for 0.5 water cement ratio than 0.4. Concrete samples which were cured for 14 days, and 28 days were tested, temperature distribution in concrete cured for 14 days is higher than that cured for 28 days. It is because of the curing time of calcium silicate hydrate (CSH) gel, and it was not fully matured and there was no moisture to finish the hydration process of cement.

Citrus bliss: potassium, sodium, and calcium silicates secrets for post-harvest diseases of fruit defense

Biotic stress significantly challenges the global citrus industry. Major post-harvest issues include diseases caused by Penicillium digitatum, Penicillium italicum, Geotrichum citri-aurantii, Alternaria alternata, and Phytophthora citrophthora. The negative impact of chemical fungicides on the environment and health necessitates eco-friendly alternatives. This study examines the effectiveness of sodium, potassium, and calcium silicates against common citrus diseases. In vitro tests evaluated mycelial growth inhibition using silicate concentrations from 0 to 10,000 ppm after 7 days at 25°C. Sodium silicate showed the highest efficacy, completely inhibiting P. digitatum and P. italicum at 2000 ppm. Potassium and calcium silicates achieved 100% inhibition against Penicillium spp. at a concentration of 1%. In vivo tests on Sidi Aissa clementines assessed the preventive and curative effects of 1, 2, and 6% silicate salt solutions. Sodium silicate prevented 41% of brown rot, 72% of sour rot, and 100% of green mold at 6%. Calcium silicate at 6% significantly reduced blue mold and black rot by 32% and 74%, respectively. Sodium silicate was most effective in curative treatments, suggesting its potential as a pre- or post-harvest spray to control P. digitatum, P. italicum, and G. citri-aurantii.