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1
Komagata, Yuya, Yuki Nagamatsu e Hiroshi Ikeda. "Comparative Bonding Analysis of Computer-Aided Design/Computer-Aided Manufacturing Dental Resin Composites with Various Resin Cements". Journal of Composites Science 7, n. 10 (7 ottobre 2023): 418. http://dx.doi.org/10.3390/jcs7100418.
Testo completoAbstract (sommario):
The use of dental resin composites adapted to computer-aided design/computer-aided manufacturing (CAD/CAM) processes for indirect tooth restoration has increased. A key factor for a successful tooth restoration is the bond between the CAD/CAM composite crown and abutment tooth, achieved using resin-based cement. However, the optimal pairing of the resin cement and CAD/CAM composites remains unclear. This study aimed to identify the optimal combination of a CAD/CAM composite and resin cement for bonding. A commercial methyl methacrylate (MMA)-based resin cement (Super-Bond (SB)) and four other composite-based resin cements (PANAVIA V5; PV, Multilink Automix (MA), ResiCem EX (RC), and RelyX Universal Resin Cement (RX)) were tested experimentally. For the CAD/CAM composites, a commercial polymer-infiltrated ceramic network (PICN)-based composite (VITA ENAMIC (VE)) and two dispersed filler (DF)-based composites (SHOFU BLOCK HC (SH) and CERASMART300 (CE)) were used. Each composite block underwent cutting, polishing, and alumina sandblasting. This was followed by characterization using scanning electron microscopy, inorganic content measurement, surface free energy (SFE) analysis, and shear bond strength (SBS) testing. The results demonstrated that the inorganic content and total SFE of the VE composite were the highest among the examined composites. Furthermore, it bonded highly effectively to all the resin cements. This indicated that PICN-based composites exhibit unique bonding features with resin cements. Additionally, the SBS test results indicated that MMA-based resin cement bonds effectively with both DF- and PICN-based composites. The combination of the PICN-based composite and MMA-based resin cement showed the best bonding performance.
2
Čáchová, Monika, Eva Vejmelková, Kateřina Šestáková, Pavel Reiterman, Martin Keppert, Dana Koňáková e Robert Černý. "Basic Physical and Mechanical Properties of Composites Based on Three Different Cements". Key Engineering Materials 677 (gennaio 2016): 186–90. http://dx.doi.org/10.4028/www.scientific.net/kem.677.186.
Testo completoAbstract (sommario):
This article is focused on cement based composites. Two cements differing in mineralogical composition are utilised as main binder in composites mixtures. Results of measured physical parameters of studied materials are presented. For the sake of comparison, a reference material with Portland cement was also prepared. Basic physical properties (measured by water vacuum saturation method and by helium pycnometry), characterizations of pore system (determined by mercury porosimetry) and mechanical properties are the matter of this study. Composites show various open porosity; the results of open porosity of materials containing special cements show higher values, in comparison with composite based on Portland cement. This fact of course influences other material characteristics - mainly mechanical properties.
3
Kumar, A. Srujan, K. Naga Meenakshi, G. Venkata Narayana reddy, G. Raju, Ch Honey e P. Anil Kumar reddy. "Development of New Composites Using Industrial by Products". International Journal of Innovative Research in Engineering and Management 10, n. 6 (30 dicembre 2022): 126–29. http://dx.doi.org/10.55524/ijirem.2022.9.6.22.
Testo completoAbstract (sommario):
In this paper thesis describes an experimental investigation of magnesium based cement mortar which consists of fly ash, magnesium oxide (MgO), magnesium Phosphate (MgPO4) and Phosphate tailings. This magnesia based cements are emerged as a viable alternative to Portland cement, with both technical and sustainability advantages. This study aims to use the mixture of cement, fly ash and magnesia. The major drawback of delayed setting time can be eliminated with the use of magnesia based cement. Hence, in this study different admixtures such as magnesium oxide, magnesium phosphate, phosphate tailings are attempted. Initial and final setting time of plain cement, fly ash cement and magnesia based cement are determined and found that the small dosage of magnesium compound reduced the setting time. Further, magnesia based cements are reported to be used along with sea water without much negative effect. In view of all these, this study proposed a magnesia based cement as an alternative for conventional Portland cement. Industrial wastes such as fly ash, and phosphate tailings are used in this study.
4
Liu, Hong Yan, Ping Zhao, Chen Feng e Rohit Sharma. "Cement-Sand Based Piezoelectric Smart Composites". Applied Mechanics and Materials 392 (settembre 2013): 9–13. http://dx.doi.org/10.4028/www.scientific.net/amm.392.9.
Testo completoAbstract (sommario):
In this paper, preliminary investigation of a new cement-sand based piezoelectric composite was conducted for potential structural engineering applications. PZT ceramic powder has been incorporated into cement material to form composite smart materials in earlier studies and showed promising outcome. However, the previous studies were limited to using only PZT and cement. In this study, PZT powder mixed with cement and sand, which is more realistic in civil engineering applications. The compressive strength of the composites with different PZT volume ratios was investigated. The results showed that embed PZTs increased the strength of the composites. Modified Sawyer-Tower circuit was applied to pole the composites in order to obtain the desired electrical properties of the composites. The mechanical and electrical properties of this type of new smart material had been investigated experimentally. Through a series of MTS compression tests, feasibility of using cement-sand based PZT composite materials in civil engineering is evaluated.
5
Magalhães, Tiago, Rita Fidalgo-Pereira, Orlanda Torres, Óscar Carvalho, Filipe S. Silva, Bruno Henriques, Mutlu Özcan e Júlio C. M. Souza. "Microscopic Inspection of the Adhesive Interface of Composite Onlays after Cementation on Low Loading: An In Vitro Study". Journal of Functional Biomaterials 14, n. 3 (7 marzo 2023): 148. http://dx.doi.org/10.3390/jfb14030148.
Testo completoAbstract (sommario):
Purpose: This study aimed to assess the layer thickness and microstructure of traditional resin-matrix cements and flowable resin-matrix composites at dentin and enamel to composite onlay interfaces after cementation on low loading magnitude. Materials and Methods: Twenty teeth were prepared and conditioned with an adhesive system for restoration with resin-matrix composite onlays manufactured by CAD-CAM. On cementation, tooth-to-onlay assemblies were distributed into four groups, including two traditional resin-matrix cements (groups M and B), one flowable resin-matrix composite (group G), and one thermally induced flowable composite (group V). After the cementation procedure, assemblies were cross-sectioned for inspection by optical microscopy at different magnification up to ×1000. Results: The layer thickness of resin-matrix cementation showed the highest mean values at around 405 µm for a traditional resin-matrix cement (group B). The thermally induced flowable resin-matrix composites showed the lowest layer thickness values. The resin-matrix layer thickness revealed statistical differences between traditional resin cement (groups M and B) and flowable resin-matrix composites (groups V and G) (p < 0.05). However, the groups of flowable resin-matrix composites did not reveal statistical differences (p < 0.05). The thickness of the adhesive system layer at around 7 µm and 12 µm was lower at the interfaces with flowable resin-matrix composites when compared to the adhesive layer at resin-matrix cements, which ranged from 12 µm up to 40 µm. Conclusions: The flowable resin-matrix composites showed adequate flowing even though the loading on cementation was performed at low magnitude. Nevertheless, significant variation in thickness of the cementation layer was noticed for flowable resin-matrix composites and traditional resin-matrix cements that can occur in chair-side procedures due to the clinical sensitivity and differences in rheological properties of the materials.
6
a, Nayeemuddin, e Ansari Faiyaz Ahmed. "EVALUATION OF CEMENT POLYMER COMPOSITES USING SPSS ANALYSIS". International Journal of Advanced Research 11, n. 11 (30 novembre 2023): 407–17. http://dx.doi.org/10.21474/ijar01/17842.
Testo completoAbstract (sommario):
Cement Polymer Mixtures are made of Cement, sand, or bulk polymers are made using polymers added to improve their compressive strength, fatigue resistance, impact, and durability. Hydraulic cement polymer composites, created with modern polymer technology, are well-known for enhancing the development of composite materials and new products. This technology aims to improve both polymer cement for new construction and its use in repairing old cement. The adhesive properties of polymer cement allow for correction and bonding of both polymer-based and conventional cement. Cement-based composite materials, such as hardened cement paste, are formed by the combination of cement, water hydration, various minerals, metals, and polymeric materials. Different combinations of these materials can result in cement binders that are used for construction. Cement, a chemical substance used as a binder, sets and hardens to bind things together. It is rarely used alone and is typically combined with sand and gravel. Polymer cement is a type of cement-polymer composite where conventional cement hydrates are replaced by polymer binders or liquid resins. It is prepared by completely replacing the hydrate binders of cement with the polymer binders or liquid resins. This mixture forms a cement-polymer composite. Cement-polymer composites are durable materials that exhibit long service life and can withstand harsh environmental conditions. They are not affected by extreme temperatures, whether hot or cold, as dry concrete has a low coefficient of expansion and can accommodate moderate movements in the design. Evaluation parameters for cement include calcium oxide, magnesium oxide, silicon dioxide, aluminum oxide, sodium oxide, potassium oxide, and sulfur trioxide.
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Rödel, Michaela, Jörg Teßmar, Jürgen Groll e Uwe Gbureck. "Tough and Elastic α-Tricalcium Phosphate Cement Composites with Degradable PEG-Based Cross-Linker". Materials 12, n. 1 (24 dicembre 2018): 53. http://dx.doi.org/10.3390/ma12010053.
Testo completoAbstract (sommario):
Dual setting cements composed of an in situ forming hydrogel and a reactive mineral phase combine high compressive strength of the cement with sufficient ductility and bending strength of the polymeric network. Previous studies were focused on the modification with non-degradable hydrogels based on 2-hydroxyethyl methacrylate (HEMA). Here, we describe the synthesis of suitable triblock degradable poly(ethylene glycol)-poly(lactide) (PEG-PLLA) cross-linker to improve the resorption capacity of such composites. A study with four different formulations was established. As reference, pure hydroxyapatite (HA) cements and composites with 40 wt% HEMA in the liquid cement phase were produced. Furthermore, HEMA was modified with 10 wt% of PEG-PLLA cross-linker or a test series containing only 25% cross-linker was chosen for composites with a fully degradable polymeric phase. Hence, we developed suitable systems with increased elasticity and 5–6 times higher toughness values in comparison to pure inorganic cement matrix. Furthermore, conversion rate from α-tricalcium phosphate (α-TCP) to HA was still about 90% for all composite formulations, whereas crystal size decreased. Based on this material development and advancement for a dual setting system, we managed to overcome the drawback of brittleness for pure calcium phosphate cements.
8
Ekincioglu, Ozgur, M. Hulusi Ozkul, Yoshihiko Ohama, Silvia Patachia e Georgeta Moise. "Effect of Epoxy Resin Addition on the Moisture Sensitivity of Macro Defect Free Polymer-Cement Composites". Key Engineering Materials 466 (gennaio 2011): 65–72. http://dx.doi.org/10.4028/www.scientific.net/kem.466.65.
Testo completoAbstract (sommario):
Macro-defect-free (MDF) cements are cement-polymer composites and were developed by Birchall et al. three decades ago. The composites are produced by mixing small amounts of polymer and water with cement. However, they have a different production method than that of cement pastes, which was inspired by rubber production. Mixtures of cement, polymer and water are processed by using a two-roll mill. The composites are known with their high flexural strengths. Unfortunately, there are not any known commercial products using MDF cements because of their poor durability under moisture. In this study, MDF cements were prepared by using poly(vinyl alcohol--vinyl acetate) PVA, calcium aluminate cements and two different types of epoxy resins. Epoxy resins were a diglycidyl ether of bisphenol A and a mixture of a diglycidyl ethers of bisphenol A and F. Durability performance was compared with respect to biaxial flexural strengths, contact angle and atomic force microscopy (AFM) for the specimens stored in water.
9
Sikora, Pawel, e Sang-Yeop Chung. "Cement-Based Composites: Advancements in Development and Characterization". Crystals 10, n. 9 (17 settembre 2020): 832. http://dx.doi.org/10.3390/cryst10090832.
Testo completoAbstract (sommario):
This Special Issue on “Cement-Based Composites: Advancements in Development and Characterization” presents the latest research and advances in the field of cement-based composites. This special issue covers a variety of experimental studies related to fibre-reinforced, photocatalytic, lightweight, and sustainable cement-based composites. Moreover, simulation studies are present in this special issue to provide the fundamental knowledge on designing and optimizing the properties of cementitious composites. The presented publications in this special issue show the most recent technology in the cement-based composite field.
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Sikora, Pawel, Didier Lootens, Maxime Liard e Dietmar Stephan. "The effects of seawater and nanosilica on the performance of blended cements and composites". Applied Nanoscience 10, n. 12 (9 marzo 2020): 5009–26. http://dx.doi.org/10.1007/s13204-020-01328-8.
Testo completoAbstract (sommario):
AbstractThis study investigates the effects of seawater and nanosilica (3% by weight of cement), on the fresh and hardened properties of cement pastes and mortars produced with two types of low heat cements: Portland pozzolana cement (CEM II) and blast furnace cement (CEM III). The heat of hydration, initial and final setting times, rheological properties, strength development, sorptivity and water accessible porosity of the cement pastes and mortars were determined. The data reveal that cement type has a significant effect on the reaction rate of cement with seawater and nanosilica (NS). Specimens produced with slag-blended cement exhibited a higher cement reaction rate and the composite produced exhibited better mechanical performance, as a result of the additional reaction of alumina rich phases in slag, with seawater. Replacement of freshwater with seawater contributes mostly to a significant improvement of early strength. However, in the case of slag-blended cement, 28 day strength also improved. The incorporation of NS results in additional acceleration of hydration processes, as well as to a decrease in cement setting time. In contrast, the addition of NS results in a noticeable increment in the yield-stress of pastes, with this effect being pronounced when NS is mixed along with seawater. Moreover, the use of seawater and NS has a beneficial effect on microstructure refinement, thus improving the transport properties of cement mortars. Overall, the study has showed that both seawater and NS can be successfully used to accelerate the hydration process of low heat blended cements and to improve the mechanical and transport properties of cement-based composites.
11
Jašek, Marek, Jiri Brozovsky, Lucie Mynarzová e Jan Hurta. "Development of Green Engineered Cementitious Composites". Advanced Materials Research 1020 (ottobre 2014): 3–8. http://dx.doi.org/10.4028/www.scientific.net/amr.1020.3.
Testo completoAbstract (sommario):
A development of fiber-cement composites is often focused on cost-effective and environmentally friendly materials (so-called green materials). Production of this material should produce less waste and it also should use less energy and less natural sources. There are numerous approaches to the development of green composites. One of the possible ways is a utilization of fly ashes instead of the cement part of composite. The paper discusses a development of green cementitious composite which incorporated fly ash materials produced in the Moravian-Silesian region as a partial replacement of the cement part of the composite.
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Davidová, Vendula, e Pavel Reiterman. "AUTOGENOUS SHRINKAGE OF COMPOSITES BASED ON PORTLAND CEMENT". Acta Polytechnica CTU Proceedings 22 (25 luglio 2019): 22–25. http://dx.doi.org/10.14311/app.2019.22.0022.
Testo completoAbstract (sommario):
Autogenous shrinkage of cement based composites is important property influencing number of their engineering application. Its ultimate value is predominantly determined by mineralogical composition of cement and its particle size distribution. Present paper introduces experimental study focused on the evaluation of various cements of grade CEM I 42.5 produced in Czech Republic in terms of shrinkage under autogenous conditions. Selected cement type is currently the most frequently used cement. Conducted study confirmed essential differences in ultimate values of shrinkage, which is partially determined by its specific surface area. Accompanying tests of mechanical properties indicate the influence of particle size distribution, which controls initial phases of cement hydration.
13
Ni, Zhuo, Xue Xiao Du, Shuai Wang, Feng Xing e Zhan Huang. "Effect of UF/Epoxy Microcapsules on Cement Composite". Advanced Materials Research 443-444 (gennaio 2012): 700–704. http://dx.doi.org/10.4028/www.scientific.net/amr.443-444.700.
Testo completoAbstract (sommario):
Effect of microcapsules on cement composites has been studied. The hydration of cement composite using microcapsules is studied by XRD and thermal techniques, showing that the addition of microcapsules has little affect on the hydration of cement. The pore size distribution and surface area of the cement composite with microcapsule are analyzed, showing a reduction in the pore content of cement composite and makes the pores smaller, which would improve durability and impermeability for designed materials. Damaging on cement and composites containing microcapsules and self-healing of these damagings can be reflected by the changes in their bending strength. When the cracks were generated in the composite, the microcapsules can release adhesive to fill in the space between the crackings, preventing cracking further growth.
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Hancharoen, Kanokon, Parames Kamhangrittirong e Pimsiree Suwanna. "Enhancement of Thermal and Sound Insulation Properties of Cement Composite Roofing Tile by Addition of Nanocellulose Coated Pineapple Fiber and Modified Rubber Tire Waste". Key Engineering Materials 861 (settembre 2020): 465–72. http://dx.doi.org/10.4028/www.scientific.net/kem.861.465.
Testo completoAbstract (sommario):
In this work, the enhancement of thermal and sound insulation properties of cement composite roofing tile with nanocellulose coated pineapple fiber and modified waste tire rubber is studied. The composite was composed of bacterial nanocellose (BNC) coated pineapple fibers, modified rubber particles, platicizer and type I Portland cement in the weight ratio of 10:50:0.8:100 with the water to cement ratio (w/c) of 0.5. The thermal conducitity of the fiber rubber cement composite could be reduced to 0.1080 ± 0.0048 W/m.K as opposed to 0.3810 ± 0.0041 and 0.5860 ± 0.0050 W/m.K for the fiber cement and the rubber cement composites, respectively. Moreover, the noise reduction coefficient of the fiber rubber cement composite could be increased to 0.2832 as opposed to 0.2143 and 0.1899 for the fiber cement and the rubber cement composites, respectively. These results revealed that adding nanocellulose coated pineapple fiber and modified rubber particles together to the cement composite can enhance the thermal insulation and sound absorption abilities of the composite roof tile significantly better than adding each constituent separately.
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Rada, Roxana, Daniela Lucia Manea, Andrzej Nowakowski e Simona Rada. "Nanocomposites Derived from Construction and Demolition Waste for Cement: X-ray Diffraction, Spectroscopic and Mechanical Investigations". Nanomaterials 14, n. 10 (20 maggio 2024): 890. http://dx.doi.org/10.3390/nano14100890.
Testo completoAbstract (sommario):
In the production of cement, raw materials can be partially substituted by regenerable waste provided from glasses, construction and demolition waste in order to reduce the environmental problem and burden of landfills. In this study, limestone–silicate composites were synthesized using starting materials such as glass waste and lime, brick, autoclaved aerated concrete (ACC), mortar or plaster waste. The structure and mechanical properties of the nano-composite materials have been studied. The mean CaCO3 crystallite sizes are higher for composites containing ACC and brick than for doping with lime, mortar and plaster. Cement-based materials are formed by replacing 2.5% of the Portland cement with limestone–silicate composites. The results indicate new possibilities for introducing 2.5%of composites in cement paste because they promote the formation of the C-S-H network, which provides strength and long stability for the cement paste. The influence of varied types of mix composites in the expired cement on the initial cracking strain and stress, tensile strength and compressive strength were investigated. The compressive strength values of composite-expired cement specimens are situated between 11.8 and 15.7 MPa, respectively, which reflect an increase from 22.9 up to 63.54% over the compressive strength of expired cement matrix.
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Karthik, A., Rooban Chandru Maris K., Suligaikumar R., Vishnu K. e Vishwa S. "STUDY ON MECHANICAL AND THERMAL PROPERTIES OF WATER HYACINTH CEMENT COMPOSITES". International Journal of Advanced Research 12, n. 03 (31 marzo 2024): 532–47. http://dx.doi.org/10.21474/ijar01/18425.
Testo completoAbstract (sommario):
This study investigates the mechanical and thermal properties of a novel cement composite incorporating water hyacinth, an abundant and under-utilized aquatic plant. The water hyacinth fibers were treated and mixed with cement to create a composite material. Various ratios of water hyacinth to cement were tested to optimize the composites properties. The mechanical properties, including compressive strength, tensile strength and flexural strength were evaluated using standard testing methods. The thermal properties were assessed by measuring the thermal conductivity and specific heat capacity of the water hyacinth cement composites. The test results indicate that the water hyacinth cement composite exhibits promising mechanical strength and improved thermal insulation compared to conventional cement. This research suggests that water hyacinth, often considered a problematic invasive species, could be effectively utilized in sustainable construction materials.
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Xiong, Guo Xuan, Min Deng, Hai Qing Huang e Ming Shu Tang. "Absorbing and Mechanical Properties of Cement-Based Composites with Nano-Titanic Oxide Absorbent". Advanced Materials Research 177 (dicembre 2010): 558–61. http://dx.doi.org/10.4028/www.scientific.net/amr.177.558.
Testo completoAbstract (sommario):
The cement-based composite absorbing materials was made of portland cement and nano-titanic oxide absorbent. The relationship of electromagnetic wave reflectivity and nanometer TiO2 contents, dispersed means, samples thickness, and effect of nanometer titanium oxide on mechanical properties of cement-based composites were discussed in details. The experiment results revealed: 1) The reflectivity of cement-based composites with nanometer titanium oxide is less than -7 dB at 8~18 GHz frequency range; 2) The least reflectivity is -16.34 dB at 16.24 GHz and the bandwidth for -10 dB is 4.5 GHz; 3) The mechanical properties of cement-based composites with nanometer titanium oxide are superior to that of cement paste.
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Khezhev, Tolya, Fatima Shogenova, Madina Bugova, Nikolay Kalambet e Inal Tanashev. "Fiber-Hypsum-Cement-Vermiculite-Concrete Composites Using Volcanic Ash". Materials Science Forum 1043 (18 agosto 2021): 67–71. http://dx.doi.org/10.4028/www.scientific.net/msf.1043.67.
Testo completoAbstract (sommario):
Fiber-gypsum-cement-vermiculite-concrete composites with use of gypsum, Portland cement, volcanic ash, expanded vermiculite and basalt fibers are considered. The results of studies of the compositions and physical and mechanical properties of fiber-gypsum-cement-vermiculite-concrete composites, the dependence of the composite characteristics on the reinforcement with basalt fibers are presented. Graphical interpretations of regression equations for compressive and flexural strength of composites are presented.
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Stevulova, Nadezda, Viola Hospodarova, Vojtech Vaclavik, Tomas Dvorsky e Tomas Danek. "Characterization of cement composites based on recycled cellulosic waste paper fibres". Open Engineering 8, n. 1 (10 novembre 2018): 363–67. http://dx.doi.org/10.1515/eng-2018-0046.
Testo completoAbstract (sommario):
AbstractNowadays, there is paying an attention to the utilization of natural, renewable and biodegradable resources of raw materials of lignocellulosic character, residues from agricultural crops and wood processing as well as waste from papermaking industry in building composite materials preparing. Also recycled fibres coming from waste paper are considered as valuable material. The objective of this study is to utilize these recycled cellulosic fibres into cement composites and characterise their impact on resulting physical and mechanical properties of fresh and hardened cement composites. Manufactured cement composites contained 0.2%, 0.3% and 0.5% addition of cellulosic fibres. In fresh fibre cement mixtures reduction in workability with increasing amount of cellulose fibres was noticed. Density as well as compressive and flexural strength of 28 and 90 days hardened fibre cement composites was tested. Distribution of cellulosic fibres with 0.5% addition in hardened fibre cement composites was also observed. The results of density determination of 28 and 90 days hardened fibre cement composites showed reduction in their values related to weight lighter concretes. Compressive strengths of fibre cement composites have shown decreasing character with increasing added amount of cellulosic fibres into the mixture up to 0.5%. Maximal decrease in compressive strength values was observed in composites containing 0.5% of cellulosic fibres. However, obtained strength parameter values of hardened composites had satisfying results for their application in construction as non-load bearing building material.
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Golewski, Grzegorz Ludwik. "Concrete Composites Based on Quaternary Blended Cements with a Reduced Width of Initial Microcracks". Applied Sciences 13, n. 12 (20 giugno 2023): 7338. http://dx.doi.org/10.3390/app13127338.
Testo completoAbstract (sommario):
This article is devoted to the study of the combined effect of siliceous fly ash (FA), silica fume (SF), and nanosilica (nS) on the cement matrix morphology and size of microcracks occurring in the Interfacial Transition Zone (ITZ) between the coarse aggregate and the cement paste of concrete composites based on ordinary Portland cement (OPC). The manuscript contains analyses of width of microcracks (Wc) occurring in the ITZ area of concretes based on quaternary blended cements and changes in ITZ morphology in the concretes in question. Experiments were planned for four types of concrete. Three of them were composites based on quaternary blended cements (QBC), while the fourth was reference concrete (REF). Based on the observations of the matrices of individual composites, it was found that the REF concrete was characterized by the most heterogeneous structure. However, substitution of part of the cement binder with active pozzolanic additives resulted in a more compact and homogenous structure of the cement matrix in each of the QBC series concretes. Moreover, when analyzing the average Wc values, it should be stated that the modification of the basic structure of the cement matrix present in the REF concrete resulted in a significant reduction of the analyzed parameter in all concretes of the QBC series. For QBC-1, QBC-2, and QBC-3, the Wc values were 0.70 μm, 0.59 μm, and 0.79 μm, respectively, indicating a decrease of 38%, almost 48%, and 30%, respectively, compared with the working condition of concrete without additives. On the basis of the above results, it can therefore be concluded that the proposed modification of the binder composition in the analyzed materials clearly leads to homogenization of the composite structure and limitation of initial internal damages in concrete.
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Xu, Dong Yu, Shi Feng Huang, Chao Ju, Zong Zhen Zhang, Xin Cheng e Min Hua Jiang. "Periodicity of Piezoelectric Ceramic Rods on Properties of 1-3 Type Cement Based Piezoelectric Composite". Advanced Materials Research 123-125 (agosto 2010): 161–64. http://dx.doi.org/10.4028/www.scientific.net/amr.123-125.161.
Testo completoAbstract (sommario):
Periodic and non-periodic 1-3 type cement based piezoelectric composites were fabricated by cut and filling technique, using P(MN)ZT ceramic as functional material and cement as matrix. The influences of periodicity of piezoelectric ceramic rods in the composites on electrical properties of all the composites were discussed. The results show that the non-periodic composites have larger dielectric factor and piezoelectric strain constant than those of the periodic composite. The impedance-frequency spectra analysis indicates that the non-periodic arrangement of ceramic rods can effectively restrict the lateral structural mode of the composite, accordingly reduces the coupling resonant between the thickness resonant mode and lateral resonant mode. The thickness electromechanical coupling coefficient of non-periodic composites is larger than that of the periodic composite. With increasing the non-periodic level of P(MN)ZT ceramic in the composites, the mechanical quality factor of the composites increases gradually. Therefore, 1-3 type cement based piezoelectric composites with different special abilities can be obtained by varying the periodic arrangement of P(MN)ZT ceramic rods in the composites.
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Arivusudar, N., e S. Suresh Babu. "Performance of ground granulated blast-furnace slag based engineered cementitious composites". Cement Wapno Beton 25, n. 2 (2020): 95–103. http://dx.doi.org/10.32047/cwb.2020.25.2.2.
Testo completoAbstract (sommario):
Engineered Cementitious Composites are belonging to the ultra-high performance fiber reinforced composites. Engineered Cemen-titious Composites are composed of fine grained ingredients like cement, fine sand, fly ash, but don’t coarse aggregate. Presence of cement in the typical Engineered Cementitious Composites mix is nearly 1000 kilograms per cubic meter, which make this material to keep far from the sustainability. The content of fly ash in the mix improves the performance of mechanical properties and durability, however, the percentage of replacement of cement has the optimum up to 30 to 40 %. In this study, an attempt is made to add granulated blast furnace slag to Engineered Cementitious Composites mix replacing the cement, along with fly ash. Five different mix proportions are used in this investigation, from 10%, to 50%, at 10% intervals of the granulated blastfurnace slag, replacing cement. The content of granulated blast-furnace slag exhibit remarkable achievement in the mechanical parameters and impact toughness.
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Saputra, Albert Artha, Vladimir Sladek, Jan Sladek e Chongmin Song. "Micromechanics determination of effective material coefficients of cement-based piezoelectric ceramic composites". Journal of Intelligent Material Systems and Structures 29, n. 5 (25 agosto 2017): 845–62. http://dx.doi.org/10.1177/1045389x17721047.
Testo completoAbstract (sommario):
Determination of effective composite properties for a real distribution of piezoelectric particles in cement matrix is considered using a representative volume element. The scaled boundary finite element method is proposed to analyse cement-based piezoelectric ceramic composites. Quadtree hierarchical meshing structure is utilized to provide a mesh that captures the material variation in the representative volume element effectively based on the colour of the piezoelectric composite’s image. Analyses with carefully selected boundary conditions are performed to obtain the effective material properties of various samples.
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Rattanachan, Sirirat, Piyanan Boonphayak e Charussri Lorprayoon. "Original article. Development of chitosan/nanosized apatite composites for bone cements". Asian Biomedicine 5, n. 4 (1 agosto 2011): 499–506. http://dx.doi.org/10.5372/1905-7415.0504.065.
Testo completoAbstract (sommario):
Abstract Background: Calcium phosphate cements (CPC) is a promising materials for bone defect repair. Nanosized apatite or calcium orthophosphate has a better bioactivity than coarser crystals. Chitosan is produced commercially from chitin that is the structural element in the exoskeleton of crustaceans such as crabs and shrimp. The mixing of nanosized apatite and chitosan may provide the consistency cement, improving mechanical properties of the set bone cement. Objective: Develop nanosized apatite powder with chitosan for bone composite cement. Materials and method: Nanosized apatite was synthesized by chemical method at low temperature and used as the single-component for bone cement. The nanosized apatite powder was characterized using X-ray diffraction method, Fourier transform infrared spectroscopy, and transmission electron microscopy. CPCs were developed based on chitosan/nanosized apatite and calcium sulfate hemihydrate. The compressive strength of the set cement was measured after one to four weeks. The phase composition and the morphology of the set cements were investigated. Results: Calcium sulfate hemihydrate was effective in increasing the compressive strength after setting in a simulated body fluid for seven days. The compressive strength of chitosan/nanosized apatite composite was about 18 MPa after soaking. Conclusion: The workability and setting time of this composite were suitable to handling for bone cement. These composite cements had a significant clinical advantage for substitution of the regenerated bone.
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Zegardło, Bartosz, Chrysanthos Maraveas, Kamil Świeczka e Antoni Bombik. "Recycling Waste Agricultural Nets as Cement Composites". Materials 17, n. 8 (16 aprile 2024): 1828. http://dx.doi.org/10.3390/ma17081828.
Testo completoAbstract (sommario):
The advancement of agricultural mesh technology has contributed to its improved properties. As a result, agricultural nets are widely adopted in large-scale farming applications, for example, in cereal crop farming. However, a consequence of this increased use of agricultural nets is the accumulation of large amounts of waste. The current paper focuses on the recycling of agricultural nets used in wrapping straw bales to develop additives and fillers in cement composites. The research details an analysis of the use of waste agricultural meshes as an ingredient in cement composites. Six test series of different mixtures were conducted. In the first four series, agricultural waste was utilised as an additive in a composite comprising aggregate and cement slurry (the amounts of wasted nets were 20, 40, 60, and 80 kg/m3). In the last test series, the recyclate utilised comprised a mixture of cement slurry and waste only. The composites were subjected to standard tests and thermal resistance tests. The results showcased that that the addition of a net worsened the workability of the concrete mixture, and with increasing amounts of addition, the consistency of the mixture could change from liquid to dense plastic. The flexural strength of the composite decreased with increasing amounts of recyclate. In subsequent test series, the flexural strength value was lower than that of the control (3.93 MPa), from 7.38% (3.64 MPa) for the composite with 20 kg/m3 of recyclate to 37.66% (2.45 MPa) for the composite with of 80 kg/m3 recyclate. The flexural strength value of the net-filled composite without aggregate was very high (10.44 MPa), where the value obtained for the control composite was 62.36% lower. The results of the compressive strength test showed a decrease in this parameter with increasing amounts of additive. The value assessed for the control composite was 27.99 MPa. As expected, the composite that had no aggregate and consisted of only recycled filler had the lowest compressive strength. The value of this parameter was 13.07 MPa, and it was 53.31% lower than that of the control composite. The results of the tests of resistance to temperatures were similar to those recorded for the composites with polypropylene fibres. All composites demonstrated a significant decrease in their compressive and flexural strength after annealing. SEM imaging showed that the net fibres were closely bonded to the cement stone. Finally, it was concluded that recyclates performed best as fillers in lightweight composites with a low density, low absorption, high flexural strength, and satisfactory compressive strength.
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Rodin, Alexander, Sergej Karpushin e Vasiliy Smirnov. "Cement Composites’ Biostability". Materials Science Forum 1011 (settembre 2020): 171–78. http://dx.doi.org/10.4028/www.scientific.net/msf.1011.171.
Testo completoAbstract (sommario):
The studies to establish the species composition of micro-mycetes inhabiting the surface of cement composites after aging in sea water have been carried out. Cement stone made on the basis of Portland cement clinker, a mineral additive and a fungicidal preparation was considered as the studied material. To determine the materials’ fouling by microorganisms, their species composition, imprints and sampling methods were used. A change in the species composition of mycobiota isolated from the cement composites’ surface modified with sodium sulfate and sodium fluoride depending on the amount of active filler, gypsum, and biocidal additives was experimentally revealed. The effectiveness of using the biocidal cement composites with an active mineral additive has been confirmed. It was found that the composites on the developed compositions showed higher resistance compared to the materials on ordinary cement. The compositions modified with biocidal additives showed a fungicidal effect.
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Ohama, Yoshihiko. "Carbon-cement composites". Carbon 27, n. 5 (1989): 729–37. http://dx.doi.org/10.1016/0008-6223(89)90206-6.
Testo completo
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Bodnárová, Lenka, Katarína Kostelanská e Filip Jankech. "The Possibilities of Application of Cellulose Fibers in Cement Composites, Monitoring the Properties". Advanced Materials Research 1054 (ottobre 2014): 85–89. http://dx.doi.org/10.4028/www.scientific.net/amr.1054.85.
Testo completoAbstract (sommario):
Application of cellulose fibers in cement composites is one of the possibilities for achieving better utility properties of these composites. This article presents findings of experimental works concerned on increasing the resistance of cement composites to high temperatures. Properties of cement composites with the addition of cellulose fibers Greencel were observed. Rheological properties of fresh composite, mechanical properties and changes of properties after heat load were evaluated. The best mechanical properties showed the samples with technical cellulose, namely with the fiber G-55T and G-700T. The process of cellulose fiber degradation at high temperatures was documented. The process of carbonization of cellulose fibers leads to the creation of pore system, which enables to increase the resistance of cement composites to high temperatures.
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Zhou, Shi Biao, An Guo Xiao, Yong Chen, Zhen Gan Chen, Ai Ping Hao, Yuan Dao Chen e Xiao Bing Huang. "The Preparation and Performance of Gypsum-Based Composites". Applied Mechanics and Materials 310 (febbraio 2013): 46–50. http://dx.doi.org/10.4028/www.scientific.net/amm.310.46.
Testo completoAbstract (sommario):
Gypsum-based composites was produced using gypsum power(cement), PVA, white latex and sawdust via pouring process. The influences of water/ cement ratio, PVA/ cement ratio and glue/ cement ratio on release time, density and impact strength of the gypsum-based composites were investigated through orthogonal experiment. The results showed that PVA strengthened obviously impact strength, and also delayed the s release time of the Gypsum-based composites. Sawdust as light filler reduced the composites density. Low content of white latex is beneficial to increase the impact strength, while high content of white latex is easy to form micelle in the gypsum crystallization process and is enclosed in crystals, which decreases the impact strength of composite materials.
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Chaipanich, Arnon, e Nittaya Jaitanong. "Fabrication and Properties of PZT-Cement-Encapsulated Carbon Composites". Key Engineering Materials 421-422 (dicembre 2009): 428–31. http://dx.doi.org/10.4028/www.scientific.net/kem.421-422.428.
Testo completoAbstract (sommario):
Lead zirconate titanate, Pb(Zr0.52Ti0.48)O3 (PZT) has excellent piezoelectric properties and has been used in a number of applications such as sensors and actuators. Recently, PZT has been used with a cement based material to produce new types of composite. These new piezoelectric-cement based composites have been developed for sensor applications in civil engineering works where these composites would provide better matching to concrete than the existing normal piezoelectric ceramic or piezoelectric-polymer composites. In this work, encapsulated carbon addition of 2% by volume was added to the PZT-cement composites using pressed-cured method. Dielectric properties of the composites were investigated from 1 to 100 kHz as a preliminary investigation. The results show that the dielectric constant was found to be higher for the composite with the addition of encapsulated carbon. The dielectric loss of the composite with the encapsulated carbon, however, was found to be less when compared to the composite with no encapsulated carbon. Scanning electron micrographs of these composites also revealed that a dense microstructure can be obtained from this method.
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Feng, Chao, Jiaxing Huang, Peihui Yan, Fei Wan, Yunfei Zhu e Hao Cheng. "Preparation and Properties of Waterborne Polypyrrole/Cement Composites". Materials 14, n. 18 (9 settembre 2021): 5166. http://dx.doi.org/10.3390/ma14185166.
Testo completoAbstract (sommario):
The electrical properties of cement are gaining importance for the application in building construction. Polypyrrole (PPy) has been widely applied in most fields because of its excellent conductivity performance, environmental friendliness, easy fabrication, and other specialties. These features made them useful for self-sensing applications. In this work, waterborne polypyrrole (WPPy) was prepared via the chemical oxidative polymerization with three kinds of hydrophilic agents: sodium lignosulfonate (LGS), sodium dodecyl sulfonate (SDS), and sodium dodecyl sulfate (SLS), and then WPPy/cement composites were prepared by mixing cement with it. The contact angle, conductivity, and microstructure of WPPy were characterized by contact angle tester, four-point probes, and SEM. The composition, microstructure, and properties of WPPy/cement composites were characterized by FTIR, TGA, XRD, and SEM. The content of LGS was 40 wt%, WPPy got the optimal comprehensive performance, the conductivity was 15.06 times of the control sample and the contact angle was reduced by 69.95%. SEM analysis showed that hydrophilic agent content had great effect on the particle size of WPPy, the average diameter of WPPy particles decreased from 200 nm to 50 nm with the increase of LGS content. The results also showed that the adding of WPPy in WPPy/cement composites can significantly improve the conductivity and compactness, optimize the microstructure of cement composite. When the content of WPPy was 1.25 wt%, WPPy/cement composite showed the lowest resistivity and saturated water content of cement composite was 8 wt%. In addition, it could also inhibit the formation of Ca(OH)2 in the early hydration process.
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Kidalova, Lucia, Nadezda Stevulova e Anton Geffert. "Possibility of Using Wood Pulp in the Preparation of Cement Composites". Selected Scientific Papers - Journal of Civil Engineering 9, n. 1 (1 giugno 2014): 51–58. http://dx.doi.org/10.2478/sspjce-2014-0006.
Testo completoAbstract (sommario):
Abstract Sustainable building materials are based on the use of renewable materials instead of non-renewable. Large group of renewable materials composes of plant fibres having high tensile strength are used as fillers into building material with reinforcement function of composite. This study aimed to establish the mechanical and physical properties of cement composites with organic fillers, such as wood pulp. Wood pulp cellulose is very interesting material as reinforcement in cement which contributes to a reduction of pollutants. Varying the producing technology (wood pulp and cement ratio in mixture) it is possible to obtain composites with density from 940 to 1260 kgm-3 and with compressive strength from 1.02 to 5.44 MPa after 28 days of hardening. Based on the experimental results, cement composites with using unbleached wood pulp reach higher values than composites based on bleached wood pulp. Volume ratio of unbleached wood pulp in composites influences water absorbability of cement composites
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Kosson, M., L. Brown e F. Sanchez. "Early-Age Performance of 3D Printed Carbon Nanofiber and Carbon Microfiber Cement Composites". Transportation Research Record: Journal of the Transportation Research Board 2674, n. 2 (29 gennaio 2020): 10–20. http://dx.doi.org/10.1177/0361198120902704.
Testo completoAbstract (sommario):
3D printed cement composites with and without carbon nanofiber (CNF) and microfiber (CF) reinforcement within the cement ink were evaluated at seven days and compared with their traditionally cast counterparts. A liquid lubrication layer at the extrusion nozzle was noted. The reinforcement type influenced the formation of the extruded filament, with underextrusion seen during 3D printing with the CNF cement ink while sudden discontinuation of extrusion was experienced during 3D printing with the CF cement ink. No noticeable interfacial region between printed filaments was observed in the 3D printed cement composites, with the exception of air cavities between printed filaments of the composite fabricated with the CNF cement ink. Lower compressive strengths were seen in the direction orthogonal to the print path for the 3D printed composites compared with the cast composites. The addition of CFs within the cement ink reduced this strength difference and led to strain softening in the post peak behavior.
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Namsone, Elvija, Genadijs Sahmenko e Aleksandrs Korjakins. "Properties of Magnesium Oxychloride and Magnesium Oxysulphate Cement Composites". Key Engineering Materials 903 (10 novembre 2021): 208–13. http://dx.doi.org/10.4028/www.scientific.net/kem.903.208.
Testo completoAbstract (sommario):
Increasing energy consumption is forcing the building sector to seek and use building materials and products that would be environmentally friendly. As one such material should be noted magnesium based cements, which production requires much lower calcination temperature than the traditional Portland cement. During the experimental research part of this work, two types of magnesia cement were produced (using magnesium chloride and magnesium sulphate brine solutions) and physical, mechanical properties of obtained cement composites were determined.
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Koňáková, Dana, Eva Vejmelková, Veronika Spedlova, Kirill Polozhiy e Robert Černý. "Cement Composites for High Temperature Applications". Advanced Materials Research 982 (luglio 2014): 154–58. http://dx.doi.org/10.4028/www.scientific.net/amr.982.154.
Testo completoAbstract (sommario):
Fiber reinforced composites designed for better thermal resistance, which can be used in constructions with a higher fire hazard, are studied. The matrix of studied composite is based on aluminous cement, because of its proved higher thermal resistance than ordinary Portland cement. Basalt sand is used as alternative aggregate replacing silica sand, and basalt fibers are employed for an improvement of mechanical performance. The presented analysis of basic physical properties, mechanical, hygric and thermal properties shows that basalt is an appropriate material for cement based composites for high temperature applications.
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Khezhev, Tolya, Tamerlan Badziev, Talib Soblirov e Timur Tamashev. "Gypsum-Cement Composites Based on Volcanic Ash". Materials Science Forum 1011 (settembre 2020): 136–43. http://dx.doi.org/10.4028/www.scientific.net/msf.1011.136.
Testo completoAbstract (sommario):
The studies’ results to determine the gypsum, ash and Portland cement components proportions, which would ensure a decrease in the specific binder consumption, as well as the ash grain composition’s effect on the properties of the gypsum cement pozzolan composite, are presented. It was revealed that the use of volcanic ash together with Portland cement in gypsum concrete composites allows reducing gypsum consumption by up to 50% without a significant decrease in strength characteristics. At the same time, the developed gypsum concrete composites have increased water resistance. The influence of the ash particle size distribution on the strength properties of the composite is ambiguous; in the compositions with a high ash content it is advisable to use larger fractions, and with a content of less than 50% ash in the composite, - the small fractions. To study the parameters’ effect of the dispersed reinforcement with basalt fibers on the properties of a gypsum-cement composite, an experiment with such a second-order composite rotatable plan as regular hexagon was conducted. It was found that the maximum values of optimization parameters are observed in the central area of the plan with and . The compressive strength of a fiber gypsum cement pozzolan composite increases by 1.15-1.18 times, when bending, by 1.56-1.72 times with respect to the strength of the initial matrix.
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Medvecky, Lubomir, Maria Giretova, Radoslava Stulajterova, Tibor Sopcak, Pavlina Jevinova e Lenka Luptakova. "Novel Biocement/Honey Composites for Bone Regenerative Medicine". Journal of Functional Biomaterials 14, n. 9 (4 settembre 2023): 457. http://dx.doi.org/10.3390/jfb14090457.
Testo completoAbstract (sommario):
New biocements based on a powdered mixture of calcium phosphate/monetite (TTCPM) modified with the addition of honey were prepared by mixing the powder and honey liquid components at a non-cytotoxic concentration of honey (up to 10% (w/v)). The setting process of the cements was not affected by the addition of honey, and the setting time of ~4 min corresponded to the fast setting calcium phosphate cements (CPCs). The cement powder mixture was completely transformed into calcium-deficient nanohydroxyapatite after 24 h of hardening in a simulated body fluid, and the columnar growth of long, needle-like nanohydroxyapatite particles around the original calcium phosphate particles was observed in the honey cements. The compressive strength of the honey cements was reduced with the content of honey in the cement. Comparable antibacterial activities were found for the cements with honey solutions on Escherichia coli, but very low antibacterial activities were found for Staphylococcus aureus for all the cements. The enhanced antioxidant inhibitory activity of the composite extracts was verified. In vitro cytotoxicity testing verified the non-cytotoxic nature of the honey cement extracts, and the addition of honey promoted alkaline phosphatase activity, calcium deposit production, and the upregulation of osteogenic genes (osteopontin, osteocalcin, and osteonectin) by mesenchymal stem cells, demonstrating the positive synergistic effect of honey and CPCs on the bioactivity of cements that could be promising therapeutic candidates for the repair of bone defects.
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Horszczaruk, Elżbieta. "Properties of Cement-Based Composites Modified with Magnetite Nanoparticles: A Review". Materials 12, n. 2 (21 gennaio 2019): 326. http://dx.doi.org/10.3390/ma12020326.
Testo completoAbstract (sommario):
Despite the many available studies on the evaluation of the influence of nanomaterials on the properties of cement-based composites, the effects of some nanoparticles have not yet been fully recognized. Among the unrecognized nanomaterials are magnetite nanoparticles (MN). The literature devoted to this subject is limited. This paper reviews state-of-the-art research carried out on the effect of MN on the properties of cement-based composites. Detailed descriptions of the processing, microstructures (hydration products), properties (hydration, workability, mechanical and functional properties, and durability), and probability applications of MN-engineered cementitious composites are presented. Particular attention has been paid to MN application methods to the cement composite. Finally, the risks, challenges, and future development of MN-modified cement-based composites is discussed.
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Madzura, M., M. N. Mazlee e Shamsul Baharin Jamaludin. "Effects of Quarry Dust as Partial Sand Replacement on Compressive Strength and Crack Profile of Cement Composites". Materials Science Forum 819 (giugno 2015): 399–404. http://dx.doi.org/10.4028/www.scientific.net/msf.819.399.
Testo completoAbstract (sommario):
This research presents the findings of experimental works in terms of mechanical properties and crack profile of cement composites containing quarry dust at different percentages as a partial sand replacement. The compositions of quarry dust were varied from 10 to 20 wt. % and were mixed into five different ratios. It was found that 0.45 water cement ratio was suitable to mix all proportions and values of slump were observed have been increased with the increasing percentage of quarry dust in cement composites. The compressive strength tests were carried out and the results showed that the compressive strength decreased at each 2.5 percent interval of quarry dust at 7 and 28 days of curing. However, the strength developments of cement composites were increased corresponding to the ages of curing. The crack profiles of cement composites have been analyzed to investigate the strength developments of the cement composites. According to the results, the cracks in the specimens were in shearing pattern at 10 and 12.5 wt. % of quarry dust in cement composites. Meanwhile, as the contents of quarry dust at 15, 17.5 and 20 wt. %, the specimens failed in shearing and splitting patterns. According to the findings of compressive strength and crack profile, the contents of quarry dust as a partial sand replacement is 12.5 wt. % were more suitable to be utilized in cement composite
40
Li, Bochen, Hongbo Liu, Jiashuo Jian, Hourui Duan e Hongshuai Gao. "Experimental Study on Flexural Properties of Polyurethane–Cement Composites under Temperature Load". Applied Sciences 12, n. 24 (13 dicembre 2022): 12799. http://dx.doi.org/10.3390/app122412799.
Testo completoAbstract (sommario):
Polyurethane cement composite is a new organic–inorganic composite material with high strength, corrosion resistance, and fast curing. It is a complement and alternative to traditional cement materials. The flexural properties of polyurethane cement composites are the basic mechanical index of the material. In order to study the flexural properties under different temperature loads, a molecular model was established, the chemical reaction process of polyurethane cement and the temperature response mechanism was analyzed, and the preparation process of polyurethane cement was proposed. Then, bending tests were carried out in strain-controlled mode to obtain the specimens' bending strength and stiffness modulus under different temperature loads. The test results showed that the tensile strength of polyurethane cement decreased first, then increased, and finally decreased with the increase in temperature, while the bending stiffness modulus decreased with the increase in temperature. Combined with the theoretical derivation, the damage mode of the samples under different temperature loads was analyzed, and the “L-type” damage strain curve was obtained. The results showed that the proposed theory could effectively explain the mechanism of action and flexural properties of polyurethane cement composites under temperature loading, which is a significant improvement to the application of polyurethane cement composites in practical engineering.
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Kazragis, Algimantas, Aušra Juknevičiūte e Albinas Gailius. "UTILIZATION OF BOON AND CHAFF FOR MANUFACTURING LIGHTWEIGHT WALLING MATERIALS". JOURNAL OF ENVIRONMENTAL ENGINEERING AND LANDSCAPE MANAGEMENT 12, n. 1 (31 marzo 2004): 12–21. http://dx.doi.org/10.3846/16486897.2004.9636810.
Testo completoAbstract (sommario):
Lightweight composites for walls and thermal insulation, containing anhydrite (An) or aluminate cement (Al), vinyl acetate (VA) or cellulose (Cl) polymeric binders and cellulose fiber fillers (boon, chaff) were produced. The best results were obtained for transportation and construction of items containing: An ≥ 30–45 %, Al ≥ 30–50 %, VA ≥ 1–5 %, Cl ≥ 0,5–5,0 %, boon or chaff ≥ 40–47 %. Polymeric binder VA for both kinds of cement is better than Cl. An is better for boon than for chaff. Aluminate cement is a good binder for both types of fiber fillers. Density r of a composite containing cements 50–60 % is less than 400 kg/m3. According to density such composite materials are light‐weight heat‐insulating materials. Density (p ≤ kg/m3) depends on the amount of cement content. Bending strength for samples with p ≤ 400 kg/m3, containing CMC is 0,6–1,3 MPa. Coefficient of thermal conductivity for samples, density with 400 kg/m3 is 0,06 W/m‐K.
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Khezhev, Tolya A., Artur V. Zhurtov e Gadzhimagomed H. Hadzhishalapov. "Heat-Resistant Cement Composites Using Volcanic Pumps and Vermiculite". Materials Science Forum 931 (settembre 2018): 489–95. http://dx.doi.org/10.4028/www.scientific.net/msf.931.489.
Testo completoAbstract (sommario):
The results of research on the development of heat-resistant cement composites using volcanic pumice and expanded vermiculite are presented. Compositions of heat-resistant cement composites are proposed that significantly reduce Portland cement consumption and simultaneously improve their heat-resistant properties. The use of basalt fibers in composites makes it possible to increase their strength, crack resistance and heat-resistant properties due to the perception of tensile temperature stresses. Part of the expensive vermiculite can be replaced by pumice without significantly increasing the average density of the composite, while their strength characteristics increase.
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Rianyoi, Rattiyakorn, R. Potong, Nittaya Jaitanong e Arnon Chaipanich. "Influence of Curing Age on Microstructure in Barium Titanate – Portland Cement Composites". Key Engineering Materials 484 (luglio 2011): 222–25. http://dx.doi.org/10.4028/www.scientific.net/kem.484.222.
Testo completoAbstract (sommario):
The objective of this study was to find out the influence of curing age on microstructure in barium titanate – Portland cement composites. Barium titanate, BaTiO3 (BT) particles was mixed with Portland Cement (PC) and BT content of 50% by volume to produce the composites. All composites were cured in chamber of 60oC and 98% relative humidity for 1, 2, 3, and 7 days. Thereafter, scanning electron microscope (SEM) was used to examine the interfacial zone between cement and BT ceramics. SEM observation indicated that the BT-PC composite cured for 7 days clearly showed calcium silicate hydrate gel (an essential hydration product of Portland cement) surrounding the BT particles and has lower porosity. In BT-PC composite cured for 1 day, the gel can be seen but of less quantity and has higher porosity which clearly affected the interfacial zone.
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Han, Seungyeon, Mohammad Shakhawat Hossain, Taeho Ha e Kyong Ku Yun. "Graphene-oxide-reinforced cement composites mechanical and microstructural characteristics at elevated temperatures". Nanotechnology Reviews 11, n. 1 (1 gennaio 2022): 3174–94. http://dx.doi.org/10.1515/ntrev-2022-0495.
Testo completoAbstract (sommario):
Abstract The focus of this research was to investigate the effects of graphene oxide (GO) on the microscopic composition, structure, pore size, and mechanical properties of GO-reinforced cement composites. Furthermore, the research explored the thermal behavior of GO-reinforced cement mortar at different elevated temperatures (250, 500, 750, and 1,000°C). This study considered three sets of GO-reinforced cement composites with 0.1, 0.2, and 0.3 wt% of GO (by weight of cement); the water–cement ratio in all the mixtures was 0.5. To characterize the chemical composition, microstructure, and hydration degree resulting from GO addition, X-ray diffraction, thermogravimetry, derivative thermogravimetry, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and micro-computed tomography (Micro-CT) were used. The experimental results revealed that GO addition changed the microstructural composition and pore diameter distribution of the cement composite. The optimal amount of GO required for improving the mechanical properties of the cement composite under both unheated and heated conditions was identified to be 0.1 wt%. GO improves the cement matrices’ ability to bind with GO nanosheets, leading to compressive strength retention and decreased micro-cracking (computed by material and defected volume changes by Micro-CT analysis). This is primarily due to the hydration products. However, the optimal amount of GO can result in nanomaterial agglomeration, thus lowering the thermal resistance of the cement composite. Overall, the study identified GO as a nano-additive with the potential to improve the strength and toughness of the cement composites. Moreover, the effect of elastic modulus was also evaluated. As a result, the GO microstructure analysis revealed that it has a porous structure with a visible crack pattern.
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Sakvarelidze, Amiran. "Cement-based Composites Moisture Conductivity Theory". Works of Georgian Technical University, n. 3(529) (27 settembre 2023): 103–14. http://dx.doi.org/10.36073/1512-0996-2023-3-103-114.
Testo completoAbstract (sommario):
It is important to establish cement-based composites moisture conductivity theory and to determine its parameters at different influences and loads to create comprehensive and improved construction calculation methods. A number of works are dedicated to the issues concerning building materials moisture transfer. It is worth mentioning that the whole raw of regularities need further clarification and study. It is necessary to develop moisture conductivity theory, which mathematical apparatus will be the base for determining the real picture of cement-based composites moisture transfer. The issues concerning the processes of cement-based composites moisture transfer are investigated in the article. It is determined that in cements easy loads within the limits of environmental relative humidity have no impact on the processes of moisture transfer. Composites moisture conductivity theory is created. A system of differential equations that precisely depicts the real picture of materials moisture conductivity is developed. Formulas determine temperature’s (T), moisture’s (W) and hydrostatic pressure’s (P) gradients impact on composites moisture conductivity in every available aspect. Formulas create closed system – three equations for three functions T, W and P. More compact formula of those equations is developed. In formulas coefficient values are given.
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Kajon, S., K. Hancharoen, P. Kamhangrittirong e P. Suwanna. "Incorporation of Rubber Waste to Fiber Cement Composite: Comparative Study of Rubber Tire Waste and Rubber Band Waste". IOP Conference Series: Materials Science and Engineering 1280, n. 1 (1 aprile 2023): 012022. http://dx.doi.org/10.1088/1757-899x/1280/1/012022.
Testo completoAbstract (sommario):
Abstract This study compares the effects of rubber tire waste and rubber band waste on physical, mechanical, and thermal properties of cement composite for roofing application. The rubber particles, prepared from waste rubber tire (RT) and/or calcium carbonate filled rubber band (RB), were mixed with cement paste and tested for workability and flexural strength. It was found that RT yields higher workability than RB when mixed with the cement paste. The rubber-cement composites (CR) with the combination of RT and RB at the RT:RB volume fraction of 1.00:0.00 (CRT), 0.75:0.25 (CRT.75/B.25) and 0.50:0.50 (CRT.50/B.50) have sufficient workability and flexural strength. When mixing different rubber particles with oil palm fibers and the cement paste to obtain CFRT, CFRT.75/B.25, CFRT.50/B.50 rubber-fiber-cement composites, the composites with higher RT content have higher flexural strength, while those with higher RB content have lower thermal conductivity, implying better thermal insulation property. More importantly, all three types of rubber-fiber-cement composites yield excellent thermal insulation property, and meet the flexural strength required by the industrial standard for the fiber-cement roof tile sheets. The results suggest that the waste rubber-waste oil palm fiber-cement composites can be viable candidates for roofing application with promising potential for energy saving.
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Choi, Yun-Wang, Sung-Rok Oh e Byung-Keol Choi. "A Study on the Manufacturing Properties of Crack Self-Healing Capsules Using Cement Powder for Addition to Cement Composites". Advances in Materials Science and Engineering 2017 (2017): 1–10. http://dx.doi.org/10.1155/2017/5187543.
Testo completoAbstract (sommario):
We fabricated crack self-healing capsules using cement powder for mixing into cement composites and evaluated the properties of the capsule manufacturing process in this study. The manufacture of the self-healing capsules is divided into core production processing of granulating cement in powder form and a coating process for creating a wall on the surfaces of the granulated cement particles. The produced capsules contain unhardened cement and can be mixed directly with the cement composite materials because they are protected from moisture by the wall material. Therefore, the untreated cement is present in the form of a capsule within the cement composite, and hydration can be induced by moisture penetrating the crack surface in the event of cracking. In the process of granulating the cement, it is important to obtain a suitable consistency through the kneading agent and to maintain the moisture barrier performance of the wall material. We can utilize the results of this study as a basis for advanced self-healing capsule technology for cement composites.
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Kidalova, Lucia, Nadežda Števulová e Anton Geffert. "Study of Cement Composites Properties with Filler Based on Wood Pulp". Advanced Materials Research 897 (febbraio 2014): 165–70. http://dx.doi.org/10.4028/www.scientific.net/amr.897.165.
Testo completoAbstract (sommario):
Sustainable building materials are based on the use of renewable materials instead of non-renewable. A large group of renewable raw materials are materials of plant origin containing cellulosic fibres which are used as filler into building material with reinforcement function of composite. This study aimed to establish the mechanical and physical properties of cement composites with organic filler, such as wood pulp. Pulp derived from wood pulping process is very interesting material as reinforcement in cement which contributes to a reduction of pollutants. In this paper, utilization of unbleached and bleached wood pulp in combination with cement matrix with emphasis on the physical and mechanical properties is studied. Varying the producing technology (wood pulp and cement ratio in mixture) it is possible to obtain composites with density from 940 to 1260 kg.m-3 and with compressive strength from 1.02 to 5.44 MPa after 28 days of hardening. The experimental results of mechanical properties indicate that cement composites with using unbleached wood pulp reaches higher values than composites based on bleached wood pulp. The percentage of water uptake increased with increasing the volume ratio of unbleached wood pulp in composite.
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Wang, Zhi, Lei Zhang, Li Ying Fan e Guo Pu Shi. "Effect of Cement Clinker on the Properties of Flue Gas Desulphurization Gypsum-Steel Slag Cementitious Composites". Advanced Materials Research 250-253 (maggio 2011): 990–93. http://dx.doi.org/10.4028/www.scientific.net/amr.250-253.990.
Testo completoAbstract (sommario):
The effects of cement clinker on the properties of flue gas desulphurization gypsum-based steel slag composites were analyzed in this article and the influence rules of setting time, final setting time, flexural strength and compressive strength of cementitious composites were also discussed. The micro-morphology of the composite was observed by scanning electron microscope. At the same time, the excitation mechanism of cement clinker on gas desulphurization gypsum-based steel slag was put forward. It was demonstrated that cement clinker with content of 2% in the composites can better stimulate the activation of steel slag and improve the mechanical properties of the composites.
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Bodnarova, Lenka, Rudolf Hela e Daniel Sedlacek. "Effect of Inorganic SiO2 Nanofibers in High Strength Cementitious Composites". MATEC Web of Conferences 278 (2019): 01009. http://dx.doi.org/10.1051/matecconf/201927801009.
Testo completoAbstract (sommario):
The paper deals with the verification of the effect of the addition of inorganic SiO2 nanofibers to cement composites. In the first stage, a stable suspension of SiO2 nanofibers was prepared in an aqueous medium. It is important to distribute nanofibers so that the nanofibers do not appear in the form of clumps and at the same time do not get damaged during the dispersion process. The ultrasonification process was used for dispersion. The dispersed suspension of SiO2 nanofibers and water was dosed together with the superplasticizing admixtures into the dry components of the cement composite and the components were homogenized. The properties of the cement composite with SiO2 nanofibers have been tested – compressive strength, flexural strength, density. Composites with the addition of SiO2 nanofibers at a dose of 0.008 % by weight of cement exhibited an increased compressive strength of up to 33 % and a 19 % greater flexural strength at doses of 0.016 and 0.032 % of cement weight than the reference sample without nanofibers. The presence of SiO2 nanofibers in the composite was monitored by scanning electron microscopy (SEM).