Academic literature on the topic 'Cement-base composite'

Sulphoaluminate cement and Lead Niobium-Magnesium Zirconate Titanate ceramic [P(MN)]ZT were used as matrix and functional phase respectively to fabricate 1-3-2 cement-based piezoelectric composites by dice and filling technique. The influences of base thickness on piezoelectric properties, electromechanical properties and acoustic impedance properties of the composites were discussed. The results show that as the base thickness increases, the piezoelectric stain factor d33 increases gradually, while the piezoelectric voltage factor g33 decreases. The planar electromechanical coupling coefficient Kp exhibits the trend of decrease, while the thickness electromechanical coupling coefficient Kt and acoustic impedance show the increasing trend. The mechanical quality factor Qm reaches the minimum (1.49) when base thickness is 2.00 mm. The results reveal that the 1-3-2 piezoelectric composite will be suitable for application by changing the base thickness.

The designed is a cement-silicate coating based on liquid sodium glass and Portland cement, modified with a complex ultra-and nanodispersed additive that includes titanium dioxide, expanded perlite sand and a dispersion of multilayered carbon nanotubes. The advantage of the designed coating is the use of Portland cement as a silicizer instead of conventionally used zinc oxide. The presented cement-silicate coating is water resistant, steam and gas proof, has good adhesion to the base and an increased durability, providing 4-5 times longer service life than those of the existing analogs. The presence of multilayered carbon nanotubes in the coating leads to the absorption of technogenic electromagnetic emission, and ultradisperse titanium dioxide promotes self-cleaning of the coating surface due to the photocatalysis effect. Expanded pearlite sand makes the coating surface textured when applying it to the base. The cement-silicate coating is used for facades decorative finishing of buildings made of ceramic bricks, cement concrete and plastered surfaces.

This study attempts to propose innovative multi-layer cement-based composites to have high impact resistance which could be used for runway. In this paper, the performances of two innovative multi-layer composite runway pavements using asphalt concrete-high strength concrete-cement-treated aggregate and asphalt concrete-high strength concrete-cement mortar in surface-base-subbase layer were evaluated under impact loads. ABAQUS/Explicit software was used to simulate loading condition and nonlinear stabilized runway pavement layers characteristics. In addition, a detailed parametric study was also carried out to explore the effects of the selected materials and load-related parameters in changing the performance of multi-layer composites. The findings of the study will be helpful to introduce protective multi-layer composite runway pavement and consequently to reduce the maintenance work of runway pavement.

This paper studies that dynamic load affects mechanical properties of materials about composite tail ore different replacement rate, different PVA fiber volume content and different plate thickness. The phenomenon of the tests and results showed that:1) PVA tailings cement-based composite materials has low damage, strong integrity and strong energy dissipation under dynamic loading. 2) When the volume content is 2%, material resistance effect is best. 3) The study proves that 30 mm plate have good ductility and Size effect influence the material mechanics performance. 4) PVA tailings cement-based composite materials under dynamic loads ,as tailings content increases the performance indicators reduced. So the engineering applications recommended replacement rate of the tailings is 50%.

Based on the rolling restoration ，the fiber-base body mechanics model is established using casing pipe as hollow fiber, cement loop and mother earth as complex base body during the repairing of destroyed casing well. The calculation formula of stress and displacement are deduced in fiber-base body according to the solid mechanics and discussed the effect of some physics quantity to displacement such as friction coefficient by way of calculation, and have deduced the calculation formula of the cement-loop damage length according to the principle of energy balance. Thus discussing the effect of the friction coefficient and degumming power to the damage of cement loop. The practical circumstances of scene indicate that it is reasonable to using this model to research the cement mantle damage mechanism.

For the old composite pavement, there are two regeneration methods: the overall recycling asphalt pavement and the cement concrete pavement and the Stratified recovery. C-B-3 gradation and cement content of 5% were used. The total content of recycled aggregate is 0, 30%, 50%, 70% and 100% and the proportion of RA and RAP is about 1:2. Through compaction test， unconfined compressive strength test and dry shrinkage test, studying the feasibility of recycling composite pavement to cement stabilized macadam base. The results show that the strength of recycled cement stabilized macadam is generally higher than that of ordinary cement stabilized macadam. The strength of regenerated cement stabilized macadam can meet the strength requirements under most traffic volume of the highways in the standard. The gradation of the mixture by stratified recovery is more uniform and the quality of the mixture can be better controlled. The addition of NA has a negative effect on the dry shrinkage properties of recycled cement stabilized macadam. However, mixing RAP into recycled cement stabilized macadam can reduce the sensitivity of materials to water and enhance the dry shrinkage property of materials.

Use artificial enhanced sewage to configurate accelerated corrosion fluids, do the research on the performance of cement based composite material to resistance microbiological corrosion in the aerobic and anaerobic environment under the condition of sewage, the compressive strength and corrosion resistant coefficient and mass loss as the evaluation index, reveals the performance of cement base composite material to resistance microbial corrosion under the action of artificial intensified sewage.

The shear/peel bond strength of a ‘no-mix’ composite orthodontic bonding resin was compared in vitro with that of a glass ionomer cement. The effect of pre-treatment of the enamel, with either phosphoric acid or polyacrylic acid, prior to using the glass ionomer cement was also assessed. The composite resin had a significantly higher bond strength than the glass ionomer cement. Simple prophylaxis and drying of the enamel achieved the best results when using the glass ionomer cement, whilst etching the tooth surface with phosphoric acid produced a significantly poorer bond to the enamel. Investigation of the site of failure showed the composite resin bonded very well to the tooth and less well to the bracket, whilst the glass ionomer adhered significantly better to the bracket base than to the tooth surface.

The cement-base composite formwork reinforced by FRP is developed to act as permanent construction formwork. Considering such properties as the minor stiffness out of the plain and the smaller bending resistance of the formwork, the matched cross support device is designed which can be recycled. In this paper, components of the support device and the corresponding functions are introduced, the technological process is described. By means of finite element program, the appropriate support distances of formwork during concrete placement are calculated, the stress and deformation performances are also analyzed. In the end, economic benefit and environment efficiency of the permanent formwork system are discussed. The above research results indicate the feasibility and economy of the support system, which present a gist for investigation and application of the permanent FRP cement composite formwork.

Semi-rigid layer is widely used as the base in China. However, the structure has resulted in many premature distresses in asphalt concrete layer. In order to overcome the problem, the composite base is introduced which is composed by both flexible and chemically stabilized material. The internal stresses are calculated by linear multilayer elastic theory and then, a comparison of the stresses of asphalt pavement with semi-rigid base and composite base is provided. The result shows that the composite base composed by all, consisting of the asphalt treated layer, graded crushed stone and cement treated layer is more suitable structure to resist cracking and the structure also has good adaptability to heavy load.

Ce travail porte sur la recherche et le développement d'un matériau de substitution osseuse permettant une implantation par chirurgie mini invasive, limitant les infections post-opératoires et dont la résorbabilité serait adaptée à la cinétique de régénération osseuse. Nous nous sommes intéressés à un ciment à base de carbonate et de phosphate de calcium (CaCO3 – CaP) dont la réaction de prise conduit à la formation d'une apatite nanocristalline analogue au minéral osseux. Dans une première partie la cinétique de prise et le produit de réaction ont été caractérisés par différentes techniques, notamment la diffraction des RX et les spectroscopies FTIR et RMN du solide. Un sel d'argent – Ag3PO4 ou AgNO3, choisis pour leurs propriétés antibactériennes – a été ensuite introduit dans la formulation. Son effet sur la cinétique de la réaction chimique de prise a été mis en évidence par traitement des spectres FTIR et RMN et un mécanisme réactionnel original impliquant les ions argent et nitrate dans la formation de l'apatite a été proposé. L'ajout d'un polysaccharide, la carboxyméthylcellulose (CMC), dans la phase solide du ciment a montré une très nette amélioration de l'injectabilité de la pâte, avec la disparition du phénomène de séparation des phases qui limite généralement l'injectabilité des ciments minéraux. La résistance à la compression et le module élastique des ciments composites ont été par ailleurs augmentés, parallèlement à une diminution de leur porosité. Différentes études in vitro en présence de cellules ou de bactéries ont enfin été réalisées et ont mis en évidence respectivement la cytocompatibilité des différentes compositions de ciments étudiées et le caractère antibactérien de ces matériaux à partir d'une certaine concentration en argent. L'implantation in vivo de compositions choisies a présenté des résultats très prometteurs quant à la résorbabilité d'un ciment composite CaCO3 - CaP/CMC/Ag et à la néoformation osseuse
The present work concerns research and development of a material for bone substitution, enabling implantation through a mini-invasive surgery, limiting post-operative infections and whose resorbability is adapted to bone regeneration kinetics. This study focused on a calcium carbonate and phosphate based cement, whose setting reaction leads to the formation of a nanocrystalline apatite, similar to bone mineral. First, the setting kinetics and the reaction products were characterised using different techniques, especially X-ray diffraction and FTIR and solid-state NMR spectroscopies. A silver salt – Ag3PO4 or AgNO3, chosen for their antibacterial properties – was then introduced in the formulation. Its effect on the setting reaction kinetics was revealed by data processing of FTIR and NMR spectra and an original reaction mechanism which involves silver and nitrates in the formation of apatite was proposed. The addition of a polysaccharide, carboxymethylcellulose (CMC), in the solid phase of the cement showed a clear improvement of the injectability of the paste, preventing the occurrence of filter-pressing phenomenon, often limiting the injectability of mineral cements. The resistance to compressive strength and elastic modulus of the composite cement were also improved together with a decrease in their porosity. Different in vitro studies were carried out in the presence of cells or bacteria and demonstrated the cytocompatibility of different cement compositions and their antibacterial properties starting at a certain silver concentration, respectively. In vivo implantation of selected compositions showed promising results concerning resorbability of a composite CaCO3 - CaP/CMC/Ag cement and the associated bone neoformation

A radiopacidade é um importante pré-requisito para materiais utilizados como base e forramento de restaurações, pois possibilita que o profissional identifique a presença do material e permita sua diferenciação com a estrutura dental adjacente. O objetivo desse estudo foi avaliar a radiopacidade de materiais indicados como base e forramento e comparar com a radiopacidade do esmalte, dentina e escala de alumínio. Para isso, foram analisadas 16 marcas comerciais de cimento de ionômero de vidro, 8 marcas de resina composta flow e 4 marcas de cimento de hidróxido de cálcio. Foram confeccionados três conjuntos de três corpos de prova de 4 mm de diâmetro, com espessuras de 1, 2 e 3 mm para cada cimento de ionômero de vidro e resina composta flow e de 1 mm para cada cimento de hidróxido de cálcio. Foram feitas secções transversais de coroas de três terceiros molares humanos para obtenção de espécimes de esmalte e dentina com espessura de 1, 2 e 3 mm. Como controle, uma escala de alumínio padrão com nove degraus de espessura foi utilizada. As tomadas radiográficas foram feitas com o sistema digital RVG 5000 Kodak (Kodak Company, França) e tempo de exposição de 0.32 segundos. As imagens obtidas foram trabalhadas no programa Image Tool® para obtenção dos valores médios de cinza. A análise estatística ANOVA, seguida pelo teste de Tukey (p0.05) detectou diferenças consideráveis entre os materiais da mesma categoria e entre as espessuras. Algumas marcas comerciais apresentaram radiopacidade inadequada segundo as normas ISO 4049 e 9917 (Ionomaster, Maxxion, Bioglass R, Bioglass F, Vidrion R e Vidrion F), apresentando radiopacidade inferior à da dentina, insuficiente para um correto diagnóstico. Todas as resinas compostas flow e cimentos de hidróxido de cálcio estudados apresentam radiopacidade superior a da dentina. As marcas comerciais Vitro Fil, Magic Glass, Vitrebond, Riva SC, Riva LC, Fill Magic, Opallis, Surefil Tetric N, Tetric, Hydro C, Hydcal e Liner apresentaram radiopacidade igual ou superior a do esmalte, em todas as espessuras. De um modo geral, o aumento de espessura dos materiais estudados aumenta significativamente sua radiopacidade. Conclui-se que existem materiais indicados como base e forramento de restaurações com radiopacidade inadequada para serem detectados radiograficamente.
Radiopacity is an important pre-requisite for base and liner materials, once it allows the professional to identify the presence of the material and makes its differentiation from the adjacent tooth structure possible. The aim of this study was to evaluate the radiopacity of liner and base materials and compare to the radiopacity of enamel, dentin and aluminum stepwedge. For this, 16 glass ionomer cements, 8 flowable resin composites and 4 calcium hydroxide cements were analysed. It was prepared three sets of three test specimens with 4 mm in diameter and thicknesses of 1, 2 and 3 mm for each glass ionomer cement and flowable composite and 1 mm for each calcium hydroxide cement. Cross sections were made from crowns of three third molars to obtain specimens of enamel and dentin with thickness of 1, 2 and 3 mm. As a control, a standard aluminum stepwedge with nine steps was used. Radiographs were taken with digital Kodak RVG 5000 (Kodak Company, France) and exposure time of 0.32 seconds. The images were analysed through the program Image Tool ® to obtain the mean grey values. Statistical test ANOVA followed by Tukey test (p 0.05) detected significant differences between the materials of the same category and between the thicknesses. The commercial brands Ionomaster, Maxxion, Bioglass R, Bioglass F, Vidrion R and Vidrion F, presented radiopacity lower than the radiopacity of dentin, insufficient for a correct diagnostic. All flowable resin composites and calcium hydroxide cements studied showed radiopacity superior than dentin. Vitro Fil, Magic Glass, Vitrebond, Riva SC, Riva LC, Fill Magic, Opallis, Surefil, Tetric N, Tetric, Hydro C, Hydcal and Liner showed radiopacity equal to or greater than the enamel for all thicknesses. In general, the increased thickness of the materials studied increases its radiopacity significantly. It was concluded that some materials indicated as base and liner for restorations have and inadequate radiopacity to be detected radiographically.

Resinas compostas apresentam contração de polimerização e a tensão gerada durante essa polimerização compete com a força adesiva na interface dente/restauração. A técnica incremental e o uso de bases com alta resiliência e módulo de elasticidade próximo ao das estruturas dentárias são técnicas desenvolvidas para tentar diminuir a tensão originada pela contração de polimerização. O presente estudo teve como objetivo analisar a influência do uso de bases de cimento de ionômero de vidro convencional e modificado por resina na qualidade e adaptação marginal na interface dentina/resina composta, após a ciclagem térmica, usando testes de resistência adesiva e análise em microscopia confocal de varredura a laser. Foram confeccionadas cavidades na face oclusal (4,5mm x 3mm x 5mm) de 60 molares humanos extraídos divididos em 6 grupos: 1 e 4 - sistema adesivo (AdperTM Single Bond; 3M ESPE) + resina composta (Filtek Z250; 3M ESPE); 2 e 5 - base de cimento de ionômero de vidro convencional (Ketac Molar Easymix; 3M ESPE) + sistema adesivo + resina composta; e 3 e 6 - base de cimento de ionômero de vidro modificado por resina (Vitrebond; 3M ESPE) + sistema adesivo + resina composta. Os grupos 4, 5 e 6 sofreram um processo de termociclagem com dois banhos (5ºC 55ºC) durante 30 segundos em 5.000 ciclos. Após 24 horas, os dentes foram seccionados em uma máquina de cortes com disco de diamante em espessura de 0,8mm. Uma fatia de cada dente foi separada aleatoriamente para análise em Microscópio Confocal para observação e mensuração de possíveis fendas marginais internas. As demais fatias foram seccionadas para a confecção de palitos (0,8mm X 0,8mm) que foram submetidos a testes de microtração em uma máquina de ensaios universal EMIC. Os resultados de resistência adesiva foram submetidos à análise de variância a um critério (ANOVA) e ao teste t-Student (p< 0,05). A presença de fendas foi avaliada com o teste da razão de verossimilhança ou teste exato de Fisher e os valores de comprimento das fendas foram avaliados pelo teste não paramétrico de Kruskal-Wallis (p<0,05). Não foram observadas diferenças estatisticamente significantes na resistência adesiva em nenhum dos grupos sem termociclagem (G1 19,28 MPa; G2 16,29 MPa; e G3 15,95MPa) ou com termociclagem (G4 19,74 MPa; G5 16,58 MPa; e G6 16,01 MPa). A análise das medidas das fendas revelou não haver diferença estatisticamente significante entre os grupos G1 (1,4µm), G2 (2,88µm) e G3 (4,63µm) e entre os grupos G4 (4,2µm), G5 (12,5µm) e G6 (5,4µm). No entanto, a termociclagem determinou um aumento do tamanho médio das fendas no grupo com base de CIV convencional (G4 12,5µm). A análise da presença ou ausência de fendas mostrou um aumento na porcentagem do número de fendas quando os espécimes foram termociclados, para os grupos sem base e com base de CIV (G1 - 30%; G2 - 25% G3 25%; G4 - 53,33%; G5 70%; e G6 30%). Os resultados mostraram, ainda, não haver relação entre o comprimento e a formação das fendas com a resistência adesiva. Conclui-se, portanto, que o uso de base de cimento de ionômero de vidro modificado por resina mantém mais estável a qualidade da interface adesiva dentina/resina composta após envelhecimento artificial com termociclagem.
Polymerization shrinkage leads to a tension into dentin/resin composite interface that can cause marginal discoloration, poor marginal adaptation, secondary caries and post-operative sensitivity. The incremental restorative technique and the use of a resilient liner with a modulus of elasticity similar to dental structures are techniques used to decrease the shrinkage polymerization tension. The aim of this in vitro study was to analyze the effect of glass-ionomer cement as a liner on the adhesive interface dentin/resin of occlusal restorations after thermocycling aging. Occlusal cavities were prepared sixty human extracted molars, divided into six groups: 1 and 4 with no liner; 2 and 5 glass-ionomer cement (Ketac Molar Easymix); and 3 and 6 resin-modified glass-ionomer cement (Vitrebond). Resin composite (Filtek Z250) was placed after application of adhesive system Adper Single Bond 2. Adhesive system was mixed with fluorescent reagent (Rhodamine B) to allow confocal microscopy analysis. After that, the specimens of groups 4, 5, 6 were thermocycled into 2 baths (5ºC 55ºC) of 30s each in 5.000 cycles. After this period, teeth were sectioned in 0,8mm slices. One slice of each tooth was randomly selected for analysis in Confocal Microscopy. The other ones were sectioned in sticks, which were submitted to micro-tensile test. The results of adhesive strength were analyzed by one way ANOVA and t-Student tests. Gap formation were analysed by Fisher test and the gaps size were analyzed by Kruskal-Wallis test (p<0,05). No statistical difference on adhesive resistance was showed between groups. Confocal Microscopy analysis showed gaps with a higher mean sizes for group 4 (12,5µm) and higger percentage of marginal gaps formation for the thermocycled groups (G1 - 30%; G2 - 25%; G4 - 53,33%; G5 70%). Groups 3 (25%) and 6 (30%) showed the lowest percentage of marginal gap formation. The results revealed that gap formation is not related to adhesive strength. It can be concluded, therefore, that the use of a resin-modified-glassionomer cement liner showed less gap formation on dentin/composite adhesive interface after artificial aging compared to conventional glass ionomer cement liner and restorations with no lining.

Este estudo teve como objetivo avaliar o efeito da base de cimento de ionômero de vidro modificado por resina (CIVMR) e das técnicas de inserção incremental de resina composta na interface de parede circundante de restauração adesiva à dentina. Foram confeccionadas cavidades com 4,5mm X 3mm X 5mm em 52 molares humanos extraídos divididos em 4 grupos: Grupo 1 (controle): Sistema Adesivo (Adper Single Bond) + Resina Composta (Filtek Z250) com inserção em 2 incrementos horizontais (Fator C = 5); Grupo 2: Sistema Adesivo (Adper Single Bond) + Resina Composta (Filtek Z250) em 4 incrementos oblíquos (Fator C=2); Grupo 3: Base de CIVMR (Vitrebond) + Sistema Adesivo (Adper Single Bond) + Resina Composta (Filtek Z250) em 2 incrementos horizontais (Fator C = 5) e Grupo 4: Base de CIVMR (Vitrebond) + Sistema Adesivo (Adper Single Bond) + Resina Composta (Filtek Z250) em 4 incrementos oblíquos (Fator C = 2). Após a restauração, os dentes permaneceram em água deionizada em estufa a 37ºC por 24 horas. Depois foram seccionados em uma máquina de cortes com disco de diamante em espessura de 0,8mm no sentido vestíbulolingual. Uma fatia de cada dente foi separada aleatoriamente para análise em Microscópio Confocal para verificação e mensuração de fendas internas na interface dentina/resina composta. As demais fatias foram seccionadas para a confecção de palitos (0,8mm X 0,8mm) que foram submetidos a testes de microtração em uma máquina de ensaios universal EMIC. Os resultados de resistência de união foram submetidos à análise de variância a dois critério ANOVA a 5% e ao teste de Fisher para as variáveis de presença de fendas internas. Não houve diferença estatisticamente significante entre os quatro grupos (p>0,05) com relação à resistência adesiva. Quanto à presença de fendas internas, foi evidenciada sua presença nos grupos 1, 3 e 4, sem diferença estatisticamente significante entre os grupos testados (p>0,05). Conclui-se, portanto, que o uso da base de cimento de ionômero de vidro modificado por resina e das técnicas de inserção incremental de resina composta não influenciam a resistência adesiva e presença de fendas da resina composta à dentina.
The aim of this study was to evaluate the effect of resin-modified-glassionomer linning and incremental technique on the bond strength of the composite restoration interface. Methods: Cavities were made (4.5mm X 3mm X 5mm) in 52 extracted human molars, divided into 4 groups: Group 1 (control) no linning + two horizontal increments (C Factor = 5); Group 2: no linning + four oblique increments (C Factor = 2); Group 3: RMGIC linning (Vitrebond) + two horizontal increments; and Group 4: RMGIC linning (Vitrebond) + four oblique increments. All teeth were restored with Adper Single Bond and Filtek Z250 and stored in deionized water at 37ºC for 24 hours before sectioned into 0.8 mm sticks (bucco-lingually). One slice of each tooth was randomly selected for confocal microscopy for analysis of the interface resin/dentin. The other slices were sectionated in sticks (mesio-distally) for microtensile test in a Universal Testing Machine (EMIC) at 0.5mm/min. The data were analyzed by Two-way ANOVA (5%) and Fishers test for variables of presence of gap. No statistical difference on adhesive strength among groups (G1 14.55 ± 4.228 MPa, G2 17.25 ± 7.31 MPa, G3 12.81 ± 4.97 MPa and G4 13.39 ± 4.115 MPa). No significant statistical difference was observed regarding the presence of gap at the interface dentin/resin among groups (p>0.05). It can be concluded, that resin-modified glass-ionomer cement linning and resin composite techniques showed no effect on the adhesive interface to dentin.

AbstractPerpetual pavement has become an important research field of highway development in China. Reasonable selection of pavement structure and ensuring the durability of the structure are one of the necessary measures to build perpetual pavements. The inverted asphalt pavement structure can not only provide high strength and good bearing capacity of semi-rigid base, but also make use of the graded crushed stones for restraining the reflection cracks of semi-rigid base. This paper presented a study on three pavement structures are, namely, a semi-rigid asphalt pavement and two inverted asphalt pavements. The performances of the three pavement structures after one million loading repetition are obtained. Taking rutting depth, deflection and dynamic response as evaluation indexes, the feasibility of inverted asphalt pavement structure as perpetual pavement structure is evaluated. It is found that the composite asphalt pavement structure with permeable asphalt mixture of large particle size as base and cement stabilized macadam as subbase has the best performance as perpetual pavement.

Nowadays, various materials are being analyzed as a possible component of pavement structure with the goal of using sustainable building materials and protecting the environment. Waste and recycled materials are added to pavement layers in order to improve it. Also, the possibility of using natural, renewable materials by incorporating them into existing standard materials is been examined. Cement-stabilized base course increases load-carrying capacity of the pavement but is prone to cracking which causes reflection cracks in an asphalt surface. Reinforcement of cement-stabilized base course can be achieved by the addition of fibers. Fibers added to the cement stabilization tend to prevent or delay the crack initiation and propagation by redistributing the resulting stresses. Considering the research conducted to-date and the need to use sustainable materials in combination with cement stabilization, some attempts are being made to achieve improvements of this pavement layer. Natural fibers are locally available, economical, renewable and degradable, and can be used as reinforcement. In the Mediterranean area, a possible source of cellulose fibers is found in the wild plant named Spanish Broom (Spartium junceum L). This paper offers an overview of research studies about fiber reinforcement of cement-stabilized base course. It also presents current research on Spanish Broom fibers in cement composites, as well as possible ways of obtaining and treating fibers. Based on the results of this research, a method for obtaining the fibers can be selected which might improve the mechanical properties of cement-stabilized course.