Regulation of Electrical, Thermal and Physical Properties of Composites Based on Carbon-Modified Portland Cement Materials

2020 ◽  
Vol 299 ◽  
pp. 264-269
Author(s):  
K.V. Tikhomirova ◽  
A.Yu. Semeykin
Keyword(s):  
Portland Cement ◽  
Thermal Characteristics ◽  
Water Repellent ◽  
Mechanical And Thermal Properties ◽  
Cement Composites ◽  
Carbon Filler ◽  
Electrically Conductive ◽  
Conductive Phase ◽  
Carbon Fillers ◽  
Adhesion Work

The article discusses aspects of the production and use of composites based on carbon-filled cement matrices. It is shown that the main problem in the technology of such composites is the regulation of the processes of structure formation and uniform distribution of the electrically conductive phase throughout the volume, to ensure stable electrical characteristics of the material. A method for solving the problem of improving the physical, mechanical and thermal properties of carbon-filled Portland cement composites by regulating the surface properties of carbon fillers, in order to reduce their concentration in the composite and the content of the aqueous phase, is proposed. It is shown that the modification of the carbon filler surface using the water-repellent agent PMS-20 reduces the adhesion work at the interface, which makes it possible to reduce the concentration of the electrically conductive phase in the composite and improve its physical, mechanical and thermal characteristics.

Behavior of Cement Composites Loaded by High Temperature

2015 ◽  
Vol 824 ◽  
pp. 121-125
Author(s):  
Veronika Špedlová ◽  
Dana Koňáková
Keyword(s):  
High Temperature ◽  
Portland Cement ◽  
High Temperatures ◽  
Experimental Program ◽  
Mechanical And Thermal Properties ◽  
Cement Composites ◽  
Basalt Fibers ◽  
Coefficient Of Thermal Conductivity ◽  
Aluminous Cement ◽  
Better Than

In this paper, there are summarized the results of an experimental program focused on basic, mechanical and thermal properties of cement composites according to the high – temperature loading. Four different materials were studied, which differed in used kind of cement and amount of fibers. As a matrix for studied composites the aluminous cement was chosen because of its resistance in high temperature. For a comparison the Portland cement was also tested. The second main ingredient used to provide better resistance in high temperatures - the basalt aggregate, was mixed in every specimen. The basalt fibers were chosen for two of the measured samples, remaining two ones were tested without fibers. The obtained data in this presented analyses show that the application of the aluminous cement leads to increase (depending on temperature) of porosity, which is the cause of decreasing of the coefficient of thermal conductivity. It can seems, that these cement composites will have low mechanical strength in high temperatures, but because of better sintering, the aluminous cement keeps its strength in high temperatures better than Portland cement.

Effect of carbon allotropes on foam formation, cure characteristics, mechanical and thermal properties of NRF/carbon composites

2020 ◽  
pp. 0021955X2097954
Author(s):  
Pollawat Charoeythornkhajhornchai ◽  
Wutthinun Khamloet ◽  
Pattharawun Nungjumnong
Keyword(s):  
Natural Rubber ◽  
Bubble Diameter ◽  
Carbon Composites ◽  
Mechanical And Thermal Properties ◽  
Foam Formation ◽  
Carbon Filler ◽  
Composite Foam ◽  
Carbon Allotropes ◽  
Blowing Agent ◽  
Rubber Composite

Natural rubber composite foam with carbon such as carbon black (CB), carbon synthesized from durian bark (CDB), graphite (GPT), graphene oxide (GO), graphene (GPE) and multi-walled carbon nanotubes (MWCNT) was studied in this work to investigate the relationship between foam formation during decomposition of chemical blowing agent mechanism and crosslink reaction of rubber molecules by sulphur. Natural rubber composite foam with carbon particle was set at 3 parts per hundred of rubber (phr) to observe the effect of carbon allotropes on foam formation with different microstructure and properties of natural rubber composite foam. The balancing of crosslink reaction by sulphur molecules during foam formation by the decomposition of chemical blowing agent affects the different morphology of natural rubber foam/carbon composites leading to the different mechanical and thermal properties. The result showed the fastest cure characteristics of natural rubber foam with 3 phr of graphene (NRF-GPE3) which was completely cure within 6.55 minutes (tc90) measured by moving die rheometer resulting in the smallest bubble diameter among other formulas. Moreover, natural rubber foam with 3 phr of MWCNT (NRF-MWCNT3) had the highest modulus (0.0035 ± 0.0005 N/m2) due to the small bubble size with high bulk density. In addition, natural rubber foam with 3 phr of GPT (NRF-GPT3) had the highest thermal expansion coefficient (282.12 ± 69 ppm/K) due to high amount of gas bubbles inside natural rubber foam matrix and natural rubber foam with 3 phr of GO (NRF-GO3) displayed the lowest thermal conductivity (0.0798 ± 0.0003 W/m.K) which was lower value than natural rubber foam without carbon filler (NRF). This might be caused by the effect of bubble diameter and bulk density as well as the defect on surface of graphene oxide compared to others carbon filler.

Preparation and Mechanical Properties of Polyethylene-Portland Cement Composites

2009 ◽  
Vol 1242 ◽  
Author(s):  
Rivas-Vázquez L.P. ◽  
Suárez-Orduña R. ◽  
Valera-Zaragoza M. ◽  
Máas-Díaz A. De la L. ◽  
Ramírez-Vargas E.
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Portland Cement ◽  
Plastic Waste ◽  
Cement Composites ◽  
Compression Tests ◽  
Standard Samples ◽  
Cement Ratio ◽  
Reinforcing Fibers ◽  
Waste Polyethylene

ABSTRACTThe effects of waste polyethylene aggregate as admixture agent in Portland cement at different addition polyethylene/cement ratios from 0.0156 to 0.3903 were investigated. The reinforced samples were prepared according the ASTM C 150 Standard (samples of 5 × 5 × 5 cm). The reinforcing fibers were milling at a size of 1/25 in diameter, form waste and used them to evaluate the effects in mechanical properties in cement-based composites. The evaluation of polyethylene as additive was based on results of density and compression tests. The 28-day compressive strength of cement reforced with plastic waste at a replacement polyethylene/cement ratio of 0.0468 was 23.5 MPa compared to the control concrete (7.5 MPa). The density of cement replaced with polyethylene varies from 2.114 (0% polyethylene) to 1.83 g/cm3 by the influence of polyethylene.

Dielectric and ferroelectric properties of 1-3 barium titanate–Portland cement composites

2011 ◽  
Vol 11 (3) ◽  
pp. S48-S51 ◽  
Author(s):  
R. Rianyoi ◽  
R. Potong ◽  
N. Jaitanong ◽  
R. Yimnirun ◽  
A. Ngamjarurojana ◽  
...  
Keyword(s):  
Barium Titanate ◽  
Portland Cement ◽  
Ferroelectric Properties ◽  
Cement Composites

Fabrication and properties of 3-3 type PZT-ordinary Portland cement composites

2021 ◽  
Vol 305 ◽  
pp. 124815
Author(s):  
Wei Liu ◽  
Lehui Zhang ◽  
Yu Cao ◽  
Jianhong Wang ◽  
Peikang Bai ◽  
...  
Keyword(s):  
Portland Cement ◽  
Ordinary Portland Cement ◽  
Cement Composites

Acoustic and Piezoelectric Properties of 0-3 Barium Zirconate Titanate-Portland Cement Composites-Effects of BZT Content and Particle Size

2013 ◽  
Vol 455 (1) ◽  
pp. 69-76 ◽  
Author(s):  
Ruamporn Potong ◽  
Rattiyakorn Rianyoi ◽  
Athipong Ngamjarurojana ◽  
Rattikorn Yimnirun ◽  
Ruyan Guo ◽  
...  
Keyword(s):  
Particle Size ◽  
Portland Cement ◽  
Piezoelectric Properties ◽  
Barium Zirconate ◽  
Cement Composites ◽  
Barium Zirconate Titanate ◽  
Zirconate Titanate

scholarly journals Properties of cement composites based on limestone depending on their granulometric composition

Vestnik MGSU ◽  
2020 ◽  
pp. 999-1006
Author(s):  
Svetlana V. Samchenko ◽  
Olga V. Alexandrova ◽  
Anton Yu. Gurkin
Keyword(s):  
Composite Materials ◽  
Portland Cement ◽  
Granulometric Composition ◽  
Coarse Grained ◽  
Cement Matrix ◽  
Cement Composites ◽  
Construction Costs ◽  
Initial Strength ◽  
Fine Grained ◽  
Additional Formation

Introduction. The use of limestone in cement compositions as an additional cementing agent solves both environmental and economic problems, namely, reduction of construction costs. In this regard, the study of the properties of the granulometric composition and volumetric content of cement composites, containing limestone, becomes increasingly important. The mission of this research is to optimize the properties of composite materials containing Portland cement and limestone by changing the granulometric composition of flour limestone. Materials and methods. Limestone, having three different Blaine milling fineness values of 250, 300 and 450 m2/kg, was used; its content reached 10, 15, 25 and 35 %. Cement and sand mortars were applied for testing purposes. The influence of the granulometric composition of limestone on the workability and compressive strength of composite cement was determined. Results. The effect of limestone on the limit shear stress becomes more pronounced when the amount of limestone increases to 25 and 35 %. This is most noticeable for limestone with a high content of fine fractions of 5–20 µm. The use of finely milled limestone increases the initial strength of the composite material. By adding 10 and 15 % of such limestone we can increase the strength by 16–20 %, and supplementary 25–35 % of limestone increases strength by 5–8 %. Strength enhancement is due to the reactivity of limestone and formation of calcium hydrocarbon aluminate 3CaO∙Al2O3∙СаСО3∙12H2O, which promotes formation of the crystal framework of the cement matrix. Additional formation of crystalline hydrates in the initial coagulation structure deteriorates the mortar workability, but increases its strength. Conclusions. The use of coarse-grained limestone significantly improves mortar workability, while the use of fine-grained limestone increases its content without reducing its strength. The granulometric composition of ground limestone shall be as close as possible to the granulometric composition of cement for the properties of composite materials containing Portland cement and limestone to be optimized.

Dispersion of graphene oxide–silica nanohybrids in alkaline environment for improving ordinary Portland cement composites

2020 ◽  
Vol 106 ◽  
pp. 103488 ◽  
Author(s):  
Junlin Lin ◽  
Ezzatollah Shamsaei ◽  
Felipe Basquiroto de Souza ◽  
Kwesi Sagoe-Crentsil ◽  
Wen Hui Duan
Keyword(s):  
Graphene Oxide ◽  
Portland Cement ◽  
Ordinary Portland Cement ◽  
Cement Composites ◽  
Alkaline Environment

Enhancement of Mechanical and Thermal Characteristics of Polyurethane-Based Composite with Silica Aerogel

2019 ◽  
Vol 951 ◽  
pp. 63-67 ◽  
Author(s):  
Jae Hyeok Ahn ◽  
Jeong Hyeon Kim ◽  
Jeong Dae Kim ◽  
Seul Kee Kim ◽  
Kang Hyun Park ◽  
...  
Keyword(s):  
Silica Aerogel ◽  
Heat Insulation ◽  
Porous Silica ◽  
Thermal Characteristics ◽  
Weight Percent ◽  
Polyurethane Foams ◽  
Mechanical And Thermal Properties ◽  
Efficient Alternative ◽  
Insulation Performance ◽  
Compressive Tests

Synthesis of polyurethane foams (PUF) with silica aerogel nanoparticles is an efficient alternative to improve the mechanical and thermal properties of the foam owing to the outstanding thermal insulation properties of porous silica aerogel nanoparticles. Silica aerogel was added into polyurethane foams at different weight percent (0, 1, 3, 5 wt.%) to observe the changes in the material properties. To confirm the applicability of the synthesized PUF to the heat insulating material, compressive tests were carried out at ambient and cryogenic temperature (20, -163°C) and the thermal conductivities were measured according to wt.%. In addition, the cell microstructure was identified using FE-SEM to analyze the effect of silica aerogels on the foam morphologies. As a result of the experiment, it was confirmed that the mechanical strength and the heat insulation performance were improved in the polyurethane foam containing 1 wt.% of silica aerogel.

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