Preparation and characterization of indoor heat blockage panel composites made of polyurethane-hybrid-foam-concrete and rice-husk-ash.

The preferable properties of indoor heat blockage material for tropical environments are blocking outside heat without absorbing and storing it inside the blockage material, therefore studying the component and the composite properties are crucial. This study, therefore, aims to prepare and characterize a new hybrid foam concrete based on Rice Husk Ash (RHA) composite panels as an indoor building material called Hybrid Foam Panel (HFP). Polyurethane made of the combination of blended polyol (catalyst and surfactant) and diphenylmethane-4,4'-diisocyanate with a constant proportion was used as a matrix, while white Portland cement and RHA with various compositions were used as fillers. The formation of polyurethane foam and related chemical reactions are confirmed and RHA in HFP composition gave significant roles in composite properties. HFP made with the right constituent composition caused much lower thermal conductivity (down to 0.22 W/mK) than the control, blocked the IR radiation heat, and it has moderate compressive strength. HFP with RHA content in consolidated parameters shows a compressive strength of 7.25-12.37 MPa; densities of 1216-1351 kg/m3 and a porosity of 62%. HFP also stands for heat at least 300 °C, thereby it is a potential interior solar heat blockade, especially in the tropical region.

Novel antibacterial and apatite forming restorative composite resin incorporated with hydrated calcium silicate.

BACKGROUND: White Portland cement is a calcium silicate material. It exhibits antibacterial properties and is biocompatible. In addition, calcium silicate-based materials are known to release calcium ions and form apatite. The purpose of this study was to develop a novel bioactive restorative resin composite with antibacterial and apatite forming properties to prevent tooth caries at the interface of teeth and restorative materials, by incorporation of hydrated calcium silicate (hCS) derived from white Portland cement. METHODS: To prepare the experimental composite resins, a 30 wt% light-curable resin matrix and 70 wt% filler, which was mixed with hCS and silanized glass powder were prepared in following concentrations: 0, 17.5, 35.0, and 52.5 wt% hCS filler. The depth of cure, flexural strength, water sorption, solubility, and antibacterial effect were tested. After immersion in artificial saliva solution for 15, 30, 60, and 90 days, ion concentration by ICP-MS and apatite formation using SEM-EDS, Raman spectroscopy and XRD from experimental specimens were analyzed. RESULTS: All experimental groups showed clinically acceptable depths of cure and flexural strength for the use as the restorative composite resin. Water sorption, solubility, released Ca and Si ions increased with the addition of hCS to the experimental composite resin. Experimental groups containing hCS showed greater antibacterial effects compared with the 0 wt% hCS filler group (p < 0.05). The 52.5 wt% hCS filler group produced precipitates mainly composed of Ca and P detected as hydroxyapatite after immersion in artificial saliva solution for 30, 60, and 90 days. CONCLUSIONS: This results show that composite resins containing hCS filler is effective in antibacterial effects. hCS has also apatite formation ability for reducing gap size of microleakage by accumulating hydroxyapatite precipitates at the restoration-tooth interface. Therefore, novel composite resin containing hCS is promising bioactive resin because of its clinically acceptable physiochemical properties, antibacterial properties, and self-sealing potential for prevention of microleakage for longer usage of restorations.

Foam Glass Granule Usage in Tile Glue Mixtures That Use a Reduced Portland Cement Amount.

In the last few years, ceramic tiles and tiles from natural rock with higher measurements were used. A huge amount of tile glue is used for high-measurement tile gluing due to a special gluing technology, which is characterized by a thicker glue layer. Due to this, a higher and higher amount of tile glue is used up during decorating. Regular tile glue mixture uses up to about 50-60% cement (according to mixture mass). In carried-out experiments, a lower amount of cement was used in tile glue mixture production (30%). Additionally, 5%, 10%, 15%, 20% and 25% of sand was replaced with small foam glass granules. These granules are made from glass waste. By using foam glass granules, lighter tile glue mixtures were produced, while reducing the cement amount can lower energy usage and CO2 emissions into the atmosphere. The main properties of tile glue were investigated as follows: flow of mixture, density, compressive strength, bending strength, tensile-adhesive strength, slip and water absorption. The properties obtained during the research prove that newly produced tile glue mixtures fulfill all requirements given to these types of mixtures. A total of 25% of foam glass granule from filler mass can be used in tile glue production.

Acid neutralizing and remineralizing orthodontic adhesive containing hydrated calcium silicate.

OBJECTIVES: The objective of this study was to evaluate an orthodontic adhesive containing hydrated calcium silicate (hCS) in terms of its bond strength with the enamel surface and its acid-neutralization and apatite-forming abilities. METHODS: The experimental orthodontic adhesives were composed of 30 wt.% resin matrix and 70 wt.% filler, which itself was a mixture of silanized glass filler and hCS in weight ratios of 100% glass filler (hCS 0), 17.5% hCS (hCS 17.5), 35% hCS (hCS 35.0), and 52.5% hCS (hCS 52.5). The degree of conversion (DC) and shear bond strength (SBS) of bovine enamel surfaces were tested. pH measurements were performed immediately upon submersion of the specimens in a lactic acid solution. The surface precipitates that formed on specimens immersed in phosphate-buffered saline (PBS) were analyzed by scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) and Raman spectroscopy after 15, 30, and 90 days. RESULTS: The experimental groups exhibited no significant differences in DC and had clinically acceptable SBS values. The hCS-containing groups showed increasing pH values as more hCS was added. hCS 52.5 produced Ca- and P-containing surface precipitates after PBS immersion, and hydroxyapatite deposition was detected after 15, 30, and 90 days. CONCLUSIONS: These results suggest that orthodontic adhesives containing hCS are effective for acid neutralization. Furthermore, hCS has an apatite-forming ability for enamel remineralization. CLINICAL SIGNIFICANCE: The novel orthodontic adhesive containing hCS exhibits a potential clinical benefit against demineralization and enhanced remineralization of the enamel surface around or beneath the orthodontic brackets.

Analyzing the Effects of Calcium Nitrate over White Portland Cement: A Multi-Scale Approach.

Calcium nitrate is considered a promising accelerator in cement-based composites, with high potential in 3D printing and cold cement concreting. The effect induced by the composition of calcium nitrate tetrahydrate (CN) accelerator into white Portland cement is evaluated here from three perspectives: (1) Fresh cement paste properties in terms of setting time and slump, (2) mechanical properties of hardened cement samples at 7 and 28 days and (3) material characteristics in terms of structure and porosity that further link the presence of the accelerator with the macroscopic performances. The compressive and flexural strength of the hardened samples, evaluated after 7 and 28 days of hydration, indicate a non-monotonous trend with CN concentration. Crystalline phase composition is investigated using X-ray diffraction (XRD). The morphology and texture are analyzed at the flexure interface by visual inspection and electron microscopy. Complementary, the porous features are investigated by NMR-relaxometry on dry and cyclohexane-filled samples. The studies confirm that CN promotes changes in the composition and morphology of hydrates, while a trend of increase in capillary porosity is outlined as well. This competition between multiscale effects may be quantified by NMR and complementary techniques to further clarify the mechanical behavior of such composites.

Crystal-Chemical and Thermal Properties of Decorative Cement Composites.

The advanced tendencies in building materials development are related to the design of cement composites with a reduced amount of Portland cement, contributing to reduced CO2 emissions, sustainable development of used non-renewal raw materials, and decreased energy consumption. This work deals with water cured for 28 and 120 days cement composites: Sample A-reference (white Portland cement + sand + water); Sample B-white Portland cement + marble powder + water; and Sample C white Portland cement + marble powder + polycarboxylate-based water reducer + water. By powder X-ray diffraction and FTIR spectroscopy, the redistribution of CO32-, SO42-, SiO44-, AlO45-, and OH- (as O-H bond in structural OH- anions and O-H bond belonging to crystal bonded water molecules) from raw minerals to newly formed minerals have been studied, and the scheme of samples hydration has been defined. By thermal analysis, the ranges of the sample's decomposition mechanisms were distinct: dehydration, dehydroxylation, decarbonation, and desulphuration. Using mass spectroscopic analysis of evolving gases during thermal analysis, the reaction mechanism of samples thermal decomposition has been determined. These results have both practical (architecture and construction) and fundamental (study of archaeological artifacts as ancient mortars) applications.

Synthesis, Characterization, and Antibacterial Evaluation of a Cost-Effective Endodontic Sealer Based on Tricalcium Silicate-White Portland Cement.

Mineral trioxide aggregate (MTA) is an ideal yet costly endodontic sealer material. Tricalcium silicate-white Portland cement (TS-WPC) seems to have similar characteristics to those of MTA. This work aims to characterize a modified TS-WPC and evaluate its antibacterial properties as a potential endodontic sealer material. The modified TS-WPC was synthesized from a 4:1 mixture of sterilized Indocement TS-WPC and bismuth trioxide using a simple solution method with 99.9% isopropanol. The mixture was stirred until it was homogenous, centrifuged, and dried. The material was then characterized using infrared spectroscopy, X-ray diffraction, and electron microscopy and subjected to antibacterial evaluation against Enterococcus faecalis using a Mueller-Hinton agar inhibition test. The results showed that the material was characterized by main functional groups of hydroxyls, silicate, bismuth trioxide, and tricalcium silicate, like those of a commercial MTA-based sealer, both tested after hydration. Modified TS-WPC before hydration showed similar powder morphology and size to the commercial one, indicating the ease of manipulation. Both materials exhibited antibacterial activity due to calcium dihydroxide's ability to absorb carbon dioxide, which is essential for the anaerobic E. faecalis, with minimum inhibitory effect and bactericidal concentrations of 12,500 ppm and 25,000 ppm, respectively. The modified TS-WPC has the potential to become a cost-effective alternative endodontic sealer material.

High-Performance Photocatalytic Cementitious Materials Containing Synthetic Fibers and Shrinkage-Reducing Admixture.

This study aims to examine the mechanical, shrinkage and chemical properties of photocatalytic cementitious materials containing synthetic fibers and a shrinkage-reducing admixture (SRA). Two types of titanium dioxide (TiO2) powders and white Portland cement were considered along with ordinary Portland cement (OPC) as a control. Two types of synthetic fibers, i.e., glass and polyethylene (PE), and an SRA with contents varying from 0% to 3% were also considered. Using the TiO2 powders and the white Portland cement was effective in reducing the nitrogen oxides (NOx) concentration in cement composites. The use of PE fibers was more effective than glass fibers in terms of the mechanical properties, i.e., the compressive strength and tensile performance. With the addition of TiO2 powders and SRA or the replacement of OPC with white cement, the mechanical properties of the cement mortar generally deteriorated. The total shrinkage of the mortar could be reduced by incorporating the fibers at volume fractions greater than 1%, and the glass fiber was more effective than the PE fiber in this regard. The TiO2 powders had no significant impact on the shrinkage reduction of the cement mortar, whereas the SRA and the white Portland cement effectively reduced shrinkage. The addition of 3% SRA decreased the total shrinkage by 43%, while the replacement of the OPC with white cement resulted in a 20% reduction in the shrinkage.

Recycling of lithium slag extracted from lithium mica by preparing white Portland cement.

In recent years, lithium slag (LS) has increased sharply with the development of lithium industry, which has caused serious environmental problems. However, the utilization of this industrial waste residue has been a difficult topic in lithium industry. In this paper, the effects of LS on mineral crystal type, ionic solid solution, decomposition temperature of CaCO3 and strength of white Portland cement clinker were studied by XRD, FT-IR, DSC, SEM-EDS and other means. The results show that LS can stabilize the M1 crystal of C3S, improve the crystallinity of C3A, and reduce the content of ACn. The LS content of 5 wt% can reduce the decomposition temperature of CaCO3 about 10 °C, but increase the low eutectic temperature of materials. Na elements tended to be dissolved in the intermediate phase, while Al3+ dissolved in calcium silicate may replace Ca2+ or Si4+. Sintering white Portland cement clinker with appropriate content of LS can effectively reduce the content of f-CaO and greatly improve the early compressive strength of clinker. Therefore, LS within 5 wt% can be used as high quality raw material of white cement, which can recycle LS.

Effects of Calcination Conditions on the Formation and Hydration Performance of High-Alite White Portland Cement Clinker.

The purpose of this study was to evaluate the effects of sintering temperature and sintering time on mineral composition of high-alite white Portland cement clinker and hydration activity of the clinker. Effects of sintering temperature and sintering time on clinker mineral composition, C3S polymorph and size and hydration heat release rate were analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM), differential scanning calorimetry&Thermogravimetric Analysis (DSC-TG) and isothermal heat-conduction calorimetry. Results shown that, with the increase of sintering temperature (1450-1525 °C) and sintering time (60-240 min), free lime (f-CaO) in clinker decreased, C3S grain size increased, and C3S crystal type changed from T3 to M type and R type, which exhibits higher symmetry. The hydration activity of different C3S crystals ranged from high to low as follows: T3→M1→M3→R@.

In vitro induction of odontogenic activity of human dental pulp stem cells by white Portland cement enriched with zirconium oxide and zinc oxide components.

Background . The aim of this in vitro study was to investigate the effect of zinc oxide (ZnO) and zirconium oxide (ZrO2) microparticles (MPs) and nanoparticles (NPs) in combination with white Portland cement (WPC) on odontogenic capacity of human dental pulp stem cells over a period of 21 days. Methods . Synthesized ZnO and ZrO2 particles were characterized using scanning electron microscopy and transmission electron microscopy. The viability of human dental pulp stem cells was measured by a 3-(4,5-dimethylthiazolyl-2-yl)-2,5- diphenyltetrazolium bromide assay at 7-, 14- and 21-day intervals after seeding on WPC disks enriched with ZnO and ZrO2 MPs and NPs. Odontogenic potential of ZnO and ZrO2 particles in combination with WPC was investigated by alkaline phosphatase (ALP) activity and ionized calcium level of supernatant culture media at different time intervals. Data were analyzed using one-way ANOVA and post hoc Tukey tests. Results . All the materials exhibited cell viability over a 21-day period, except for WPC with ZnO NPs on day 7, although it was not statistically significant (P>0.05). The ALP activity and ionized calcium level increased in all the groups compared to the control group (P<0.05). ZnO NPs had superior effect on odontogenic activity and calcium ion release compared to ZnO MPs (P=0.046). There was no significant difference between ZrO2 MPs and NPs in odontogenic activity (P>0.05). Conclusion . WPC enriched with ZnO and ZrO2 increased ALP activity and calcium ion release of human dental pulp stem cells over a period of 21 days in vitro.

Análisis químico elemental y de fases por medio de PIXE, DSC, TGA y DRX en MTA Angelus® y un cemento Portland blanco / Elemental chemical composition and phase analysis by means of PIXE, DSC, TGA, and DRX of MTA Angelus® and a white Portland cement

Resumen: El mineral trióxido agregado (MTA) es un cemento usado principalmente para sellar perforaciones en órganos dentales debido a que endurece en presencia de humedad, está compuesto por cemento Portland y trióxido de bismuto. Objetivo: Analizar y comparar por medio de PIXE, DSC, TGA y DRX la composición química elemental y de fases del cemento MTA Angelus® y de un cemento Portland blanco (CPB-CA). Material y métodos: MTA Angelus® blanco y un cemento Portland blanco fueron analizados con PIXE en un acelerador de partículas; el análisis de fases cristalinas se realizó por medio de DRX y contrastado los picos con los de base de datos del ICDD, el DSC se realizó en un calorímetro hasta 900 °C. Resultados: PIXE detectó como elementos de mayor porcentaje fueron aluminio, silicio y calcio para ambos cementos; habiendo diferencias en los porcentajes de azufre; el bismuto sólo se detectó en MTA Angelus®. Se detectaron como elementos traza cobre y estroncio en el MTA Angelus®, además de zirconio en CPB-CA. La relación entre silicio-calcio y silicio-aluminio en los dos cementos es similar. Se identificaron tres fases cristalinas en ambos cementos, silicato dicálcico, silicato tricálcico y aluminato tricálcico; sin embargo, se identificó Bismita en el MTA Angelus® y sulfato de calcio en forma de yeso en CPB-CA, que se logró corroborar con la ayuda de la técnica DSC. Conclusiones: Se logró observar la baja cantidad de yeso en MTA Angelus® por medio de la calorimetría. Tanto las fases cristalinas como la composición química elemental son similares en ambos cementos.

Abstract: Mineral trioxide aggregate (MTA) is a cement mainly used to seal tooth perforations; this is due to the fact that it hardens when in presence of humidity. It is composed of Portland cement and Bismuth trioxide. Objective: To analyze and compare with PIXE, DSC, TGA and DRX elementary chemical and phase composition of MTA Angelus® cement with a white Portland cement (WPC). Material and methods: MTA Angelus® white and a white Portland cement were analyzed with PIXE in a particle accelerator, phase analyses were conducted with XRD contrasting peaks with those in the ICDD database. DSC was conducted in a calorimeter up to 900 oC. Results: PIXE detected the following as greater percentage elements: aluminum, silica and calcium for both cements. Differences were found with sulfur percentages; Bismuth was only detected in MTA Angelus®. Trace elements of copper and strontium were detected in MTA Angelus® and zirconium in WPC. Relationship between silica-calcium and silica-aluminum was similar in both cements. In both cements, three crystalline phases were detected: dicalcium silicate, tricalcium silicate and tricalcium aluminate. Nevertheless, Bismite was identified in MTA Angelus® and calcium sulfate in the form of gypsum in WPC, this was corroborated with DSC technique. Conclusions: In MTA Angelus®, low gypsum amounts were observed by means of calorimetry. In both cements, crystalline phases and elemental chemical composition were similar.

Chemical analysis and biological properties of two different formulations of white portland cements.

White Portland cement (WPC) has generated research interests in the field of endodontics. This study compared between the properties of two formulations of white Portland cement (WPC) of different origin (Malaysia [MA] and Egypt [EG]). WPCs with and without calcium chloride dihydrate were prepared. Scanning electron microscope (SEM), energy dispersive X-ray micro-analysis, and X-ray diffraction were used for surface morphology evaluation, elemental, and phase analysis, respectively. After the preparation of optimized serial dilutions, the cytotoxicity was evaluated on human periodontal ligament fibroblasts (HPLFs) and dental pulp stem cells (DPSCs) using methyl-thiazol-diphenyltetrazolium assay after 24 and 72 h. Cell attachment properties were examined under SEM after 24 and 72 h. Results showed that the surface morphology and chemical composition of both formulations demonstrated detectable variations. The cytotoxicity evaluation showed different cellular responses of HPLFs compared to DSPCs. Both formulations favored the viability of HPLFs. However, the fast set formulations demonstrated severe cytotoxicity on DPSCs. Significant differences between EGWPC and MAWPC were identified (p < 0.05). The cell attachment properties were favorable; however, HPLFs attached and spread over the samples better than DPSCs. In conclusion, WPC of different origin may show differences in chemical and biological properties. The addition of CaCl2 ·2H2 O to WPC can affect its properties. Human cell types may react differently towards different formulations of WPCs. SCANNING 38:303-316, 2016. © 2015 Wiley Periodicals, Inc.

Apatite formation on calcined kaolin-white Portland cement geopolymer.

In this study, calcined kaolin-white Portland cement geopolymer was investigated for use as biomaterial. Sodium hydroxide and sodium silicate were used as activators. In vitro test was performed with simulated body fluid (SBF) for bioactivity characterization. The formation of hydroxyapatite bio-layer on the 28-day soaked samples surface was tested using SEM, EDS and XRD analyses. The results showed that the morphology of hydroxyapatite was affected by the source material composition, alkali concentration and curing temperature. The calcined kaolin-white Portland cement geopolymer with relatively high compressive strength could be fabricated for use as biomaterial. The mix with 50% white Portland cement and 50% calcined kaolin had 28-day compressive strength of 59.0MPa and the hydroxyapatite bio-layer on the 28-day soaked sample surface was clearly evident.

Healing of apical rarefaction of three nonvital open apex anterior teeth using a white portland cement apical plug.

The major challenge of performing root canal treatment in an open apex pulp-less tooth is to obtain a good apical seal. MTA has been successfully used to achieve a good apical seal, wherein the root canal obturation can be done immediately. MTA and White Portland Cement has been shown similarity in their physical, chemical and biological properties and has also shown similar outcome when used in animal studies and human trials. In our study, open apex of three non vital upper central incisors has been plugged using modified white Portland cement. 3 to 6 months follow up revealed absence of clinical symptoms and disappearance of peri-apical rarefactions. The positive clinical outcome may encourage the future use of white Portland cement as an apical plug material in case of non vital open apex tooth as much cheaper substitute of MTA.