Cement Composites for High Temperature Applications

2014 ◽  
Vol 982 ◽  
pp. 154-158 ◽  
Author(s):  
Dana Koňáková ◽  
Eva Vejmelková ◽  
Veronika Spedlova ◽  
Kirill Polozhiy ◽  
Robert Černý
Keyword(s):  
High Temperature ◽  
Thermal Resistance ◽  
Mechanical Performance ◽  
Fire Hazard ◽  
Silica Sand ◽  
Cement Composites ◽  
Reinforced Composites ◽  
The Matrix ◽  
Aluminous Cement ◽  
Temperature Applications

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.

Influence of Basalt Fibres and Aggregates on the Thermal Expansion of Cement-Based Composites

2014 ◽  
Vol 1054 ◽  
pp. 17-21 ◽  
Author(s):  
Dana Koňáková ◽  
Veronika Špedlová ◽  
Monika Čáchová ◽  
Eva Vejmelková ◽  
Robert Černý
Keyword(s):  
Thermal Expansion ◽  
High Temperature ◽  
Open Porosity ◽  
Thermal Strain ◽  
Experimental Results ◽  
Silica Sand ◽  
Cement Composites ◽  
The Matrix ◽  
Aluminous Cement

The influence of basalt fibres and aggregates on the thermal expansion of cement composites is analyzed. Four different composite mixes based on aluminous cement are designed and tested. Experimental results show that the application of basalt components leads to the reduction of the increase of open porosity after high temperature loading from 47% to 36%, as compared with the reference mix. The matrix densities exhibit almost similar values for all studied composites; the differences are only up to 16%. The thermal strain is more than 50% lower when basalt aggregates are used instead of silica sand.

Fibre-Matrix Interface Development during High Temperature Exposition of Long Fibre Reinforced SiOC Matrix

2013 ◽  
Vol 592-593 ◽  
pp. 401-404
Author(s):  
Zdeněk Chlup ◽  
Martin Černý ◽  
Adam Strachota ◽  
Martina Halasova ◽  
Ivo Dlouhý
Keyword(s):  
High Temperature ◽  
Crack Formation ◽  
Fracture Behaviour ◽  
Point Of View ◽  
Reinforced Composites ◽  
Matrix Interface ◽  
Significant Damage ◽  
The Matrix ◽  
Fibre Matrix ◽  
Fibre Reinforced Composites

The fracture behaviour of long fibre reinforced composites is predetermined mainly by properties of fibre-matrix interface. The matrix prepared by pyrolysis of polysiloxane resin possesses ability to resist high temperatures without significant damage under oxidising atmosphere. The application is therefore limited by fibres and possible changes in the fibre matrix interface. The study of development of interface during high temperature exposition is the main aim of this contribution. Application of various techniques as FIB, GIS, TEM, XRD allowed to monitor microstructural changes in the interface of selected places without additional damage caused by preparation. Additionally, it was possible to obtain information about damage, the crack formation, caused by the heat treatment from the fracture mechanics point of view.

scholarly journals Effect of Sand Size on Mechanical Performance of Cement-Based Composite Containing PVA Fibers and Nano-SiO2

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 325 ◽  
Author(s):  
Yi-Feng Ling ◽  
Peng Zhang ◽  
Juan Wang ◽  
Yan Shi
Keyword(s):  
Fracture Toughness ◽  
Mechanical Performance ◽  
Silica Sand ◽  
Fine Aggregate ◽  
Reinforced Composites ◽  
Nano Sio2 ◽  
Flexural Tensile Strength ◽  
Fracture Performance ◽  
Sand Particles ◽  
Sand Size

Both finer sand and nanoparticles have a filler effect on mechanical performance of cement-based composite. In this paper, the influence of sand size in mechanical performance of cement-based composites, containing polyvinyl alcohol fiber (PVA) and nano-SiO2 (NS), was investigated. The studied mechanical performance, included compressive, flexural, tensile strength, and fracture toughness. A 0.9% volumetric percentage of PVA and a 2% NS mass content were used to make cement-based composites with a 0.38 w/b. Silica sand with four sand size ranges (380–830 μm, 212–380 μm, 120–212 μm and 75–120 μm) was adopted as fine aggregate. The 28-day curing was conducted for all specimens under 20 °C and 95% humidity. It is concluded that the finer sand decreased workability and mechanical strength of PVA-reinforced composites containing NS. However, this reduction was very limited for the sand particles less than 380 µm. The ultimate tensile stain, fracture toughness, and energy were decreased as sand size declined. In addition, the fracture performance of the composites was greatly dependent on fracture energy.

Mullite Whisker Reinforced Zirconia Toughened Alumina for High Temperature Applications

2014 ◽  
Author(s):  
Taylor Robertson ◽  
Xiao Huang ◽  
Richard Kearsey
Keyword(s):  
High Temperature ◽  
Cost Effective ◽  
Mechanical Tests ◽  
Processing Route ◽  
Molten Salt Method ◽  
The Matrix ◽  
Mullite Whiskers ◽  
Monolithic Ceramics ◽  
Zirconia Toughened Alumina ◽  
Temperature Applications

Particulate enhanced oxide ceramics are an attractive class of materials for high temperature applications because they possess many of the high temperature capabilities of monolithic ceramics but also have enhanced mechanical properties due to their multi-phase structure. High temperature structural ceramics have the potential to operate above at higher temperatures than current super alloys; however, processing costs and lack of reliability has prevented their commercialization. In this work a particulate reinforced ceramic composed entirely of oxides is proposed as a more oxidation resistant and cost effective structural ceramic which will have potentially improved resistance to environmental degradation. Zirconia Toughened Alumina (ZTA), as the matrix, has enhanced toughness, strength, and creep resistance over single phase alumina or zirconia. ZTA can further be strengthened by the incorporation of SiC type whiskers; however, these whiskers are prone to deterioration at temperatures above 1000°C through oxidation. In this work Mullite, in whisker form, is proposed as the reinforcement to ZTA due to its stability in oxidizing atmospheres at high temperatures. Mullite whiskers are grown through the molten salt method and incorporated into the ZTA matrix using a colloidal processing route in this study. The composition of the ZTA matrix is 15wt% Yttria stabilized Zirconia (YSZ), 85 wt% α-Alumina. The Mullite whiskers make up 20 vol% of the composite, yielding a final composition of 71.6 wt% Alumina, 12.7 wt% YSZ, and 15.6 wt% Mullite. The green compacts are fired in a two stage sintering process incorporating atmospheric pressure sintering to 92% density (seal the pore channels) and then hot isostatic pressure pressing (HIP) to increase the density. Samples have been tested for room temperature flexural strength using a three point bend test and fracture toughness through Gong’s Vickers indentation method. The results of microstructure study and mechanical tests are reported in this paper.

High Temperature Composite of Aluminous Cement with Addition of Metakaolin and Ground Bricks Dust

2013 ◽  
Vol 486 ◽  
pp. 406-411 ◽  
Author(s):  
Ondřej Holčapek ◽  
Pavel Reiterman ◽  
Petr Konvalinka
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
High Temperatures ◽  
Raw Materials ◽  
Cement Composites ◽  
Basalt Fibers ◽  
Aluminous Cement ◽  
The Common ◽  
Temperature Exposure ◽  
Sufficient Strength

The following article deals with the study of mechanical properties of aluminous cement composites exposure to high temperatures. The newly designed mixtures that resist the action of high temperatures 1000 °C find their application in various fields of industrial production or in the form of fire wall for protection bearing structures. All the mechanical properties such as compressive strength and tensile strength in bending were measured on samples 160x40x40 mm. These samples were exposed to temperatures 600 °C and 1000 °C and one group of samples was reference and stayed in laboratory condition. Aluminous cement unlike the common Portland cement keeps sufficient strength even after high temperature exposure. For ensuring required ductility the basalt fibers were added to the mixture. In an effort to use of secondary raw materials as a replacement for cement as well as a suitable binder was used metakaolin and ground brick dust. Very convenient characteristics of these components are their latent hydraulic potential that makes interesting hydration products.

Whisker-Reinforced Ceramic Matrix Composites

MRS Bulletin ◽  
1987 ◽  
Vol 12 (7) ◽  
pp. 66-72 ◽  
Author(s):  
J. Homeny ◽  
W.L. Vaughn
Keyword(s):  
High Temperature ◽  
Energy Dissipation ◽  
Mechanical Performance ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Matrix Composites ◽  
Mechanical Reliability ◽  
Interfacial Bond ◽  
High Fracture ◽  
The Matrix

Whisker-reinforced ceramic matrix composites have recently received a great deal of attention for applications as high temperature structural materials in, for example, advanced heat engines and high temperature energy conversion systems. For applications requiring mechanical reliability, the improvements that can be realized in fracture strength and fracture toughness are of great interest. Of particular importance for optimizing the mechanical reliability of these composites is the effect of the whisker/matrix interfacial characteristics on the strengthening and toughening mechanisms. Whisker reinforcements are primarily utilized to prevent catastrophic brittle failure by providing processes that dissipate energy during crack propagation. The degree of energy dissipation depends on the nature of the whisker/matrix interface, which can be controlled largely by the matrix chemistry, the whisker surface chemistry, and the processing parameters.It is generally believed that a strong interfacial bond results in a composite exhibiting brittle behavior. These composites usually have good fracture strengths but low fracture toughnesses. If the interfacial bond is weak, the composite will not fail in a catastrophic manner due to the activation of various energy dissipation processes. These latter composites tend to have high fracture toughnesses and low fracture strengths. Generally, the interface should be strong enough to transfer the load from the matrix to the whiskers, but weak enough to fail preferentially prior to failure. Thus, local damage occurs without catastrophic failure. It is therefore necessary to control the interfacial chemistry and bonding in order to optimize the overall mechanical performance of the composites.

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.

Experimental Analysis of Hydrothermal Curing Influence on Properties of Fiber-Cement Composite

2015 ◽  
Vol 732 ◽  
pp. 55-58 ◽  
Author(s):  
Ondřej Holčapek ◽  
Pavel Reiterman ◽  
Petr Konvalinka
Keyword(s):  
Tensile Strength ◽  
High Temperature ◽  
Cement Composite ◽  
Cement Composites ◽  
Research Activity ◽  
Temperature Resistance ◽  
Hydrothermal Curing ◽  
Aluminous Cement ◽  
Curing Condition ◽  
Strength In Bending

Special industrial application of fiber-cement composites is currently one important issue of concrete industry and research activity. The field of refractory and high-temperature resistance materials is very large and contains the cement composites too. Hydrothermal curing together with using aluminous cement with refractory basalt aggregates and fibers shows high potential for its applications in high temperature. These composite is characterized by compressive strength over 140 MPa and tensile strength in bending 12 MPa (investigated on specimens 40 x 40 x 160 mm). After exposure to temperature 1000 °C these parameters are 60 MPa in compression respective 6 MPa in bending. Achieved values are significantly higher than in the case of laboratory curing condition and there are suitable especially for prefabricated fire resistance cladding or other special application in the industry.

Fiber Coatings Derived from Molecular Precursors

MRS Bulletin ◽  
1991 ◽  
Vol 16 (4) ◽  
pp. 59-65 ◽  
Author(s):  
H. Eric Fischer ◽  
David J. Larkin ◽  
Leonard V. Interrante
Keyword(s):  
Mechanical Performance ◽  
Stress And Strain ◽  
Reinforced Composites ◽  
Processing Conditions ◽  
Molecular Precursors ◽  
Inorganic Composites ◽  
The Matrix ◽  
Experimental Treatments ◽  
Interface Layers ◽  
Reinforcing Fiber

It is generally agreed that the mechanical performance of continuous fiber-reinforced composites will depend to a large extent on the nature of the interface between the fiber and the matrix. In the case of many inorganic composites, compositional and/or morphological gradients can arise over an extended region between the matrix and reinforcing fiber as a result of processing conditions, mechanical forces, or chemical interactions. The term “interphase” has been applied to such a region.There have been numerous theoretical and experimental treatments of this subject in an effort to quantify the stress and strain in the interphase region, and to correlate the presence of such forces with the mechanical performance of the attendant composites. Much of the experimental work has emphasized controlling the nature of the interphase through careful control of the processing conditions or by the introduction of special interface layers, often by applying a coating to the reinforcing fiber prior to incorporating it into the matrix.

Sign in / Sign up

Export Citation Format

Share Document