Pure Tricalcium Silicate Research Articles

Effect of interface properties between functionalized cellulose nanocrystals and tricalcium silicate on the early hydration mechanism of cement

The hydration process is a critical stage in the development of the properties of cement-based materials，however, the influence of cellulose nanocrystals (CNC) on cement during the early hydration is controversial. This study uses pure tricalcium silicate (C3S) as the object to analyze the influence of carboxyl CNC (CCNC) and sulfonic CNC (SCNC) on hydration parameters such as hydration rate, types, quality, and pore structure of hydration products during the early hydration period. The dissolution of C3S and the interaction between fluids and minerals at the C3S/CNC interface is the core mechanism of the early hydration. Ultraviolet and energy spectrum analyzed adsorption between CNC and C3S from a physical perspective, and molecular dynamics simulations deeply discussed the adsorption behavior between C3S/Water/CNC at nano-scale. The results show that CNC prolongs the hydration induction and acceleration period, delays the early hydration of C3S; CCNC exhibits a more significant effect than SCNC. Under the action of Ca-O and hydrogen bonds, CNC will adsorb on the surface of C3S and cover its surface, reducing the number of waters on the surface of C3S. Hydrophilic CNC molecules attract water molecules close to the CNC chain, and solidifying water molecules prevents it from entering the hydration surface. CNC also restricts the diffusion of Ca2+ on the surface of C3S to outside, improving the stability of Ca-O coordination, promoting the accumulation of hydration products at the C3S surface, and inhibiting the dissolution of C3S. Understanding the effect of functionalized CNCs on the diffusion and sedimentation mechanism of water molecules and Ca2+ during hydration can provide insights for guiding the design of nanomaterials with strong compatibility with cement systems and enlarging the application of functionalized nanomaterials in cement-based materials engineering fields.

Modification mechanism of cellulose nanocrystals in cement

To investigate the modification mechanism of cellulose nanocrystals (CNCs) in cement, this paper simplifies the complex cement system to pure tricalcium silicate (C3S) mineral components. The hydration characteristics of C3S mixed with different amounts of CNCs and the chemical environment of the hydration products were explored. CNCs have a similar effect to superplasticizers in reducing the hydration exothermic. The addition of CNCs promotes the growth of Ca(OH)2 on the (001) crystal plane and increases the grain size of Ca(OH)2. CNCs provide additional nucleation sites, which reduces the degree of polymerization and shortens the main chain length of the generated C-S-H. The separate-hydration test confirmed that the CNCs successively adsorbed calcium ions and silicate ions, which promoted the formation of C-S-H gel coating on the surface of CNCs. The elucidation of the modification mechanism of CNCs provides theoretical guidance for its application in cement.

Impact of maturation time on the shear bond strength of an alkasite restorative material to pure tricalcium silicate based cement: An in-vitro experimental study

Impact of maturation time on the shear bond strength of an alkasite restorative material to pure tricalcium silicate based cement: An in-vitro experimental study

Physico-chemical characterization, bioactivity evaluation and cytotoxicity of PDA nanoparticles doped tricalcium silicate cements

The long setting time and insufficient strength of tricalcium silicate (TCS)-based cements are a main disadvantage for their clinical use. Therefore, the aim of this study was to develop an advanced TCS cement by incorporating polydopamine (PDA) nanoparticles. The setting time and compressive strength of TCS cement with incorporated PDA nanoparticles were evaluated. Furthermore, the effect of PDA nanoparticles on the apatite formation and the cytotoxicity of hydrated cements was investigated. The results show that the initial and final setting time of the cements were reduced by 63.9% and 46.7%, respectively, by adding 4 wt% PDA nanoparticles. The compressive strength of the cements reached 39.6 MPa by the addition of 4 wt% PDA and was thus 37.5% higher than that of pure TCS. Furthermore, the apatite-forming ability was also improved with the incorporation of 4 wt% PDA and the good biocompatibility was readily confirmed by using a fibroblast cell line. Our results showed that a TCS cement reinforced with PDA nanoparticles could be a promising dental restorative material.

Physicochemical and biological properties of new tricalcium silicate-based repair material doped with fluoride ions and zirconium oxide as radiopacifier.

This study evaluated the physicochemical and biological properties of novel reparative materials composed of pure tricalcium silicate (Ca3 SiO5 ), Ca3 SiO5 doped with fluoride ions (Ca3 SiO5 -F) and their association with ZrO2 (Ca3 SiO5 + ZrO2 , Ca3 SiO5 -F + ZrO2 ), in comparison with Biodentine (BIO). Setting time radiopacity, pH, solubility, and dimensional change were evaluated based on ISO 6876 Standard. Volumetric change and flow/filling were assessed by microcomputed tomography (micro-CT). Biological properties were evaluated by the MTT assay 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide), Neutral Red (NR), cell migration, alkaline phosphatase activity (ALP), and Alizarin Red Staining (ARS) assays. Statistical analysis was performed by ANOVA, Tukey, or Bonferroni tests (α=.05). Ca3 SiO5 -F + ZrO2 had higher radiopacity, shorter setting time, and lower solubility and volumetric loss than BIO (p < .05). Ca3 SiO5 -F + ZrO2 had flow and filling capacity similar to BIO (p > .05). All the cements evaluated had an alkaline pH. Ca3 SiO5 -F + ZrO2 demonstrated cell viability similar to negative control (p > .05), increase in ALP activity in 7 days, mineralized nodule production in 21 days and repair capacity according to cell migration. In conclusion, Ca3 SiO5 -F + ZrO2 had adequate setting time, radiopacity, solubility, and dimensional change. This material presented low volumetric change besides flow and filling capacity in micro-CT assessment. In addition, Ca3 SiO5 -F + ZrO2 was biocompatible and bioactive, suggesting its use as reparative material.

Physicochemical, biological, and antibacterial evaluation of tricalcium silicate-based reparative cements with different radiopacifiers

ObjectiveTo evaluate tricalcium silicate-based (TCS) experimental materials, associated with zirconium oxide (ZrO2), calcium tungstate (CaWO4) or niobium oxide (Nb2O5) radiopacifiers, in comparison with MTA Repair HP (Angelus). MethodsPhysicochemical tests: setting time, radiopacity, pH and solubility. In vitro assays: cytotoxicity: MTT and Neutral Red – NR; cell bioactivity: alkaline phosphatase activity (ALP), Alzarin red staining (ARS) and real time PCR (qPCR). Antibacterial activity: direct contact on Enterococcus faecalis in the planktonic form. Physicochemical and ARS data were submitted to ANOVA/Tukey tests; antibacterial activity, to Kruskall–Wallis and Dunn tests; MTT, NR, ALP and qPCR were analyzed by ANOVA/Bonferroni tests (α = 0.05). ResultsTCS + CaWO4 presented the longest setting time and MTA HP the shortest. Except for TCS, all the materials presented radiopacity above 3 mmAl. The cements had alkaline pH, antibacterial activity, low solubility and no cytotoxic effects. The highest ALP activity occurred in 14 days, especially to TCS, TCS + ZrO2 and TCS + CaWO4. TCS + ZrO2, TCS + Nb2O5 and MTAHP had higher mineralized nodule formation than those of the negative control (NC). After 7 days, there was no difference in mRNA expression for ALP, when compared to NC. However, after 14 days there was no overexpressed ALP mRNA, especially TCS + Nb2O5, in relation to the CN. All the materials presented antimicrobial action. SignificanceThe pure tricalcium silicate associated with ZrO2, CaWO4 or Nb2O5 had appropriate physicochemical properties, antibacterial activity, cytocompatibility and induced mineralization in Saos-2, indicating their use as reparative materials.

Determination of atomistic deformation of tricalcium silicate paste with high‐volume fly ash

AbstractWe examined the effect of incorporating high‐volume fly ash on the atomic arrangement and interatomic deformation behavior of calcium silicate hydrates in tricalcium silicate paste upon exposure to external forces. The interatomic structural changes and strains under compressive load were assessed using synchrotron in situ high‐energy X‐ray scattering‐based atomic pair distribution function analysis. Three different types of strains, which were (a) macroscopic strains from gauges on the surfaces of specimen, (b) strains in a reciprocal space (Bragg peak shift), and (c) strains in real space (PDF peak shift), were compared to each other. All monitored and calculated strains for tricalcium silicate‐fly ash (50 wt% fly ash) paste were compared with the counterparts of the pure tricalcium silicate paste. Pair distribution function analysis in the range of r &lt; 10 Å indicated that the atomic arrangement of tricalcium silicate‐fly ash was similar to that of synthetic calcium silicate hydrates followed by that of pure tricalcium silicate paste. Moreover, the pair distribution function refinement results revealed that the calcium silicate hydrate structure in tricalcium silicate‐fly ash paste was similar to tobermorite 11 Å, unlike that in pure tricalcium silicate paste. The interatomic strain of tricalcium silicate‐fly ash in the real space (r &lt; 20 Å) was smaller than that of tricalcium silicate under compression, which suggested that the incompressibility of calcium silicate hydrates at atomistic scale was enhanced by the incorporation of fly ash into it. This was likely to be caused by the increased silicate polymerization of calcium silicate hydrates, which was attributed to the increase in the amount of silicate in their structure via the addition of fly ash.

COMPARISON OF DENTINAL TUBULAR PENETRATION OF THREE BIOCERAMIC SEALERS

Objective: The main objective of endodontic treatment is to remove microorganisms from the root canal space and prevents reinfection. Deep penetration of the dentinal tubule is advantageous because it increases the contact area between the root canal filling material and dentin, thereby increasing the sealing quality of the entire root canal system. Bioceramic sealers are biocompatible, nontoxic, non-shrinking, hydrophilic, and stable, do not expand during setting, and can form hydroxyapatite, which then forms chemical bonds with dentin to compare the abilities of three types of bioceramic-based sealers to penetrate the dentinal tubules.Methods: Obturation used three types of bioceramic sealers. Group 1 (calcium phosphate silicate), Group 2 (a mixture of tricalcium silicate and resin), and Group 3 (pure tricalcium silicate) were observed using a scanning electron microscope and measurement of the penetration distance with ImageJ.Results: The bioceramic sealers had statistically significant differences in penetration distance into dentinal tubules (p’s&lt;0.001). The mean penetration value of Group 1 (calcium phosphate silicate) was 115.99 μm, Group 2 (a mixture of tricalcium silicate and resin) was 209.28 μm, and Group 3 (pure tricalcium silicate) was 84.07 μm.Conclusion: Although all three bioceramic sealers penetrated the dentinal tubules, they exhibited differences in their penetration capabilities. Group 2 had the deepest penetration, likely due to the resin content.

Synthesis of pure tricalcium silicate powder by the Pechini method and characterization of hydrated cement

Synthesis of pure tricalcium silicate powder by the Pechini method and characterization of hydrated cement

The microstructure and surface morphology of radiopaque tricalcium silicate cement exposed to different curing conditions

ObjectiveTricalcium silicate is the major constituent phase in mineral trioxide aggregate (MTA). It is thus postulated that pure tricalcium silicate can replace the Portland cement component of MTA. The aim of this research was to evaluate the microstructure and surface characteristics of radiopaque tricalcium silicate cement exposed to different curing conditions namely at 100% humidity or immersed in either water or a simulated body fluid at 37°C. MethodsThe materials under study included tricalcium silicate and Portland cements with and without the addition of bismuth oxide radiopacifier. Material characterization was performed on hydrated cements using a combination of scanning electron microscopy (SEM) with X-ray energy dispersive (EDX) analyses and X-ray diffraction (XRD) analyses. Surface morphology was further investigated using optical profilometry. Testing was performed on cements cured at 100% humidity or immersed in either water or Hank's balanced salt solution (HBSS) for 1 and 28 days at 37°C. In addition leachate analysis was performed by X-ray fluorescence of the storage solution. The pH of the storage solution was assessed. ResultsAll the cements produced calcium silicate hydrate and calcium hydroxide on hydration. Tricalcium silicate showed a higher reaction rate than Portland cement and addition of bismuth oxide seemed to also increase the rate of reaction with more calcium silicate hydrate and calcium hydroxide being produced as demonstrated by SEM and XRD analysis and also by surface deposits viewed by the optical profilometer. Cement immersion in HBSS resulted in the deposition of calcium phosphate during the early stages following immersion and extensive calcification after 28 days. The pH of all storage solutions was alkaline. The immersion in distilled water resulted in a higher pH of the solution than when the cements were immersed in HBSS. Leachate analysis demonstrated high calcium levels in all cements tested with higher levels in tricalcium silicate and bismuth replaced cements. SignificanceTricalcium silicate cement is more bioactive than Portland cement as demonstrated by various characterization techniques. The bioactivity was monitored by measuring the production of calcium hydroxide and the formation of calcium phosphate when in contact with simulated body fluids.

Characterization and analyses of acid‐extractable and leached trace elements in dental cements

Determination of the elemental constitution and investigation of the total and leachable arsenic, chromium and lead in Portland cement, pure tricalcium silicate, Biodentine, Bioaggregate and mineral trioxide aggregate (MTA) Angelus. The chemical composition of Portland cement, MTA Angelus, tricalcium silicate cement, Biodentine and Bioaggregate was determined using X-ray fluorescence (XRF). Measurements of arsenic, lead and chromium were taken with inductively coupled plasma-mass spectrometry (ICP-MS), following acid digestion on the hydrated material and on leachates of cements soaked in Hank's balanced salt solution (HBSS). All the cements investigated had a similar oxide composition with the main oxide being calcium and silicon oxide. Both the Portland cement and MTA Angelus had an additional aluminium oxide. The dental cements included a radiopacifying material. All the materials tested had higher acid-extractable arsenic content than the level set by ISO 9917-1 (2007) and an acceptable level of lead. Regardless these high levels of trace elements present in the materials, the leaching in HBSS was minimal for all the dental material tested in contrast to the high levels displayed by Portland cement. Dental materials based on tricalcium silicate cement and MTA Angelus release minimal quantities of trace elements when in contact with simulated body fluids. The results of acid extraction could be affected by nonspecific matrix effects by the cement.

Density and water content of nanoscale solid C–S–H formed in alkali-activated slag (AAS) paste and implications for chemical shrinkage

Alkali-activated slag (AAS) paste was analyzed using small-angle neutron scattering (SANS). The scattering response indicates that the microstructure consists of a uniform matrix of hydration product with a high surface area studded with unhydrated cores of slag particles. In contrast with portland cement paste, no surface fractal scattering regime was detected, and elevated temperature curing (at 60°C) had no detectable effect on the microstructure at any length scale studied. The specific surface area of the AAS pastes is about 25% higher than that of a portland cement paste cured under the same conditions. The composition and mass density of the nanoscale solid C–S–H phase formed in the AAS paste was determined using a previously developed neutron scattering method, in conjunction with a hydration model. The result ((CaO)0.99–SiO2–(Al2O3)0.06–(H2O)0.97, d=(2.73±0.02) g/cm3) is significantly lower in calcium and in water as compared to portland cement or pure tricalcium silicate paste. These values were used to calculate the chemical shrinkage that would result from complete hydration of the AAS paste. The result, (12.2±1.5) cm3 of volumetric shrinkage per 100g of unhydrated cement, is about twice the amount of chemical shrinkage exhibited by normal cement pastes.

Hydration kinetics of tricalcium silicate by calorimetric methods

The kinetics of the cement hydration reaction is a relevant issue in the cement research field, particularly in the presence of additional inorganic and organic components that consistently increase the complexity of the cement paste. In the present study, the hydration reaction of pure tricalcium silicate has been monitored by different calorimetric approaches: the conventional Isothermal Conduction Calorimetry (IC) and a novel Differential Scanning Calorimetry (DSC) protocol. The measured hydration curves have been modeled by using the Boundary Nucleation and Growth Model (BNGM) to extract thermodynamic parameters of the early stages of the hydration reaction. IC and DSC methods provide similar results in terms of rate constants, linear growth, and nucleation rates even though the IC accesses the total evolved heat while DSC discloses the fraction of unreacted water. The validation of the DSC approach as a reliable analytical method to the study of cement hydration kinetic is of particular importance because it allows following very long hydration processes, such as those of pastes containing organic retarders or superplasticizers. The thermodynamic and kinetic parameters for the tricalcium silicate setting has been also evaluated and discussed as a function of the surface area of the powder.

Hydration of alite containing aluminium

The most important phase in Portland cement is tricalcium silicate, which leads during its hydration to the nucleation and growth of calcium silicate hydrate [referred to as C–S–H, (CaO)x–SiO2–(H2O)y]. The development of this hydrate around the cement grains is responsible for the setting and hardening of cement pastes. The general term for designating the tricalcium silicate in cements is alite. This name relates to all polymorphs containing various foreign ions inserted in their structure. These ions may influence the intrinsic reactivity, and once released during the dissolution, they may interact also with C–S–H. One of the most likely species to be inserted in the alite structure is aluminium. In order to investigate if aluminium plays an important role in C3S reactivity, alite containing 0·1 wt-% aluminium has been synthesised. Alite hydration was followed and compared with pure tricalcium silicate one. The ion concentration evolution at a very early age shows the formation of a C–S–H containing aluminium ions, and it has been evidenced that this hydrate does not act as nuclei to C–S–H growth that induces a delay before acceleration of hydration commonly named ‘dormant period’.

Evidence of Solid Water Bridges Found in Hydrating Tricalcium Silicate Paste

The D2O hydration of pure tricalcium silicate (Ca3SiO5) was examined at 23°C with parallel measurements using deuterium NMR spectral analysis, deuterium NMR T1 relaxation measurements at several magnetic fields, isothermal calorimetry, scanning electron microscopy, and Vicat needle tests. The results show that the maximum rate of decrease in the deuterium T1 relaxation time of the D2O resonance, the maximum rate of increase in heat production, and the maximum rate of decrease in Vicat needle penetration occur simultaneously within experimental error. Together with results from other recent deuterium NMR studies in our laboratory, these observations support the new hypothesis that the formation of solid water bridges between closely adjacent developing hydrate surfaces causes initial setting. As a confirmatory experiment, it was found that microwave heating immediately after setting, i.e. immediately after zero Vicat needle penetration, softened the paste sufficiently to once again allow some needle penetration, and furthermore, that upon cooling, the paste reset. This process could be repeated several times.

Effects of Saccharide Set Retarders on the Hydration of Ordinary Portland Cement and Pure Tricalcium Silicate

The effects of aliphatic sugar alcohols (e.g., threitol, xylitol, sorbitol) on the hydration of tricalcium silicate (C3S) and ordinary portland cement (OPC) were investigated and compared with those of sucrose, a well‐established cement set retarder. Only sugar alcohols which contain threo diol functionality retarded the setting of C3S and OPC, their efficacy increasing with the number of threo hydroxy pairs and, to a smaller extent, with the overall population of hydroxy groups. None, however, were as effective as sucrose. The initial and final setting times increased exponentially with the concentration of saccharide, although the hydration of OPC was less inhibited than that of C3S. Saccharides function as “delayed accelerators,” that is, cement hydration is first inhibited and then proceeds faster than in saccharide‐free cement. This behavior is consistent with the theory that the induction period is controlled by slow formation and/or poisoning of the stable calcium silicate hydrate (CSH) nuclei. The early inhibiting influence of saccharides on CSH precipitation is apparently stronger than on the growth of crystalline calcium hydroxide. Saccharides did not negatively affect the degree of hydration and compressive strength of fully set OPC paste; on the contrary, sorbitol yielded modest increases.

Hydration Kinetics and Microstructure Development of Normal and CaCl2-Accelerated Tricalcium Silicate Pastes

Microstructure development and the kinetics of hydration of pure tricalcium silicate (C3S) and CaCl2-accelerated C3S pastes were investigated by performing isothermal calorimetry and in situ small-angle neutron scattering (SANS) measurements on parallel specimens during the first few days of hydration, as well as on 28-day old specimens hydrated under the same curing conditions (water/cement ratio = 0.5, 20 °C). Calorimetry experiments were also performed over a range of hydration temperatures from 10 to 40 °C. The calorimetry data were analyzed by applying a previously described boundary nucleation and growth model. The model indicates that CaCl2 significantly increases the rate of nucleation of hydration product on the surface of the C3S particles but has relatively little effect on the product growth rate. The SANS measurements indicate that the composition and density of the calcium−silicate−hydrate (C−S−H) nanoparticles is unchanged by the addition of CaCl2. However, in the CaCl2-accelerated paste th...

Characterization of Ca 3SiO 5/CaCl 2 composite cement for dental application

Objectives The purpose of this study was to investigate the effect of CaCl 2 on the setting time, pH values and compressive strength of tricalcium silicate, and the in vitro bioactivity and compatibility of Ca 3SiO 5/CaCl 2 composite paste was also studied to explore the possibility for using as a root canal filling material. Methods Composite cements were obtained by mixing Ca 3SiO 5 and different amounts of CaCl 2 (0, 5%, 10% and 15%) with deionized water as liquid phase. The composite cement and pure tricalcium silicate were compared for setting time, pH value, compressive strength, in vitro bioactivity and compatibility. Results With the addition of CaCl 2 from 0% to 15%, the initial setting time and final setting time decreased obviously from 90 to 50 min and from 180 to 90 min, respectively. The compressive strength of the Ca 3SiO 5/CaCl 2 composite cement after setting for 7 days increased obviously from 5.28 to 23.46 MPa when the content of CaCl 2 increased from 0% to 10%. Furthermore, the paste with up to 15% of CaCl 2 showed good ability to induce the formation of hydroxyapatite (HA), and the dissolution extracts of the Ca 3SiO 5/CaCl 2 composite paste also have a stimulatory effect on L929 cell proliferation in a certain concentration range. Significance The results indicated that the Ca 3SiO 5/CaCl 2 composite cement had good self-setting properties, bioactivity and compatibility, and may be used as a novel root canal filling material.

Structural Studies of Hydrated Tricalcium Silicate by Neutron Powder Diffraction

Structure refinements have been carried out on the pure tricalcium silicate (C3S) and the hydrated C3S with the D2O–C3S mass ratio, which is 0.5, using neutron powder diffraction (NPD). The multi-phase Rietveld analysis of the hydrated C3S revealed the coexistence with the Ca(OD)2 (trigonal phase) and the unhydrated C3S (triclinic one). The Ca(OD)2 phase was hardly observed on the NPD patterns in the first ∼6 h of hydration, while the several Bragg reflections of Ca(OD)2 appeared drastically from ∼6 to ∼24 h, and then the hydration reaction rate was gradually suppressed. We could apply the Avrami-model to the initial hydration reaction process of C3S.

The effect of a retarder on the early stages of the hydration of tricalcium silicate

Cement is used in the oil industry to line oil wells. The major component of oilwell cement is tricalcium silicate (C3S), which is responsible for the initial thickening of the cement slurry. It is important to control the time that it takes for this slurry to thicken, and this is achieved in practice by the addition of chemical retarders, which delay the onset of thickening. In this paper, the action of a retarder whose main effect is to form a complex with calcium ions is investigated by use of a model for the hydration of C3S previously investigated by Preece, Billingham and King (2001). It is found that such a retarder can significantly increase the thickening time of pure tricalcium silicate.