scholarly journals Development of Composite for Thermal Barriers Reinforced by Ceramic Fibers

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Ondřej Holčapek ◽  
Jaroslava Kot'átková ◽  
Pavel Reiterman
Keyword(s):  
Flexural Strength ◽  
Thermal Loading ◽  
Elevated Temperatures ◽  
Ceramic Powder ◽  
Hydrothermal Condition ◽  
Optimal Dosage ◽  
Ceramic Fibers ◽  
Cement Replacement ◽  
Hydrothermal Curing ◽  
Aluminous Cement

The paper introduces the development process of fiber-reinforced composite with increased resistance to elevated temperatures, which could be additionally increased by the hydrothermal curing. However, production of these composites is extremely energy intensive, and that is why the process of the design reflects environmental aspects by incorporation of waste material—fine ceramic powder applied as cement replacement. Studied composite materials consisted of the basalt aggregate, ceramic fibers applied up to 8% by volume, calcium-aluminous cement (CAC), ceramic powder up to 25% by mass (by 5%) as cement replacement, plasticizer, and water. All studied mixtures were subjected to thermal loading on three thermal levels: 105°C, 600°C, and 1000°C. Experimental assessment was performed in terms of both initial and residual material properties; flow test of fresh mixtures, bulk density, compressive strength, flexural strength, fracture energy, and dynamic modulus of elasticity were investigated to find out an optimal dosage of ceramic fibers. Resulting set of composites containing 4% of ceramic fibers with various modifications by ceramic powder was cured under specific hydrothermal condition and again subjected to elevated temperatures. One of the most valuable benefits of additional hydrothermal curing of the composites lies in the higher residual mechanical properties, what allows successful utilization of cured composite as a thermal barrier in civil engineering. Mixtures containing ceramic powder as cement substitute exhibited after hydrothermal curing increase of residual flexural strength about 35%; on the other hand, pure mixture exhibited increase up to 10% even higher absolute values.

scholarly journals Physical and Mechanical Properties of Composites Made with Aluminous Cement and Basalt Fibers Developed for High Temperature Application

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Pavel Reiterman ◽  
Ondřej Holčapek ◽  
Marcel Jogl ◽  
Petr Konvalinka
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Fracture Energy ◽  
Bulk Density ◽  
Thermal Loading ◽  
Ceramic Powder ◽  
Physical And Mechanical Properties ◽  
Partial Replacement ◽  
Basalt Fibers ◽  
Aluminous Cement

Present paper deals with the experimental study of the composition of refractory fiber-reinforced aluminous cement based composites and its response to gradual thermal loading. Basalt fibers were applied in doses of 0.25, 0.5, 1.0, 2.0, and 4.0% in volume. Simultaneously, binder system based on the aluminous cement was modified by fine ground ceramic powder originated from the accurate ceramic blocks production. Ceramic powder was dosed as partial replacement of used cement of 5, 10, 15, 20, and 25%. Influence of composition changes was evaluated by the results of physical and mechanical testing; compressive strength, flexural strength, bulk density, and fracture energy were determined on the different levels of temperature loading. Increased dose of basalt fibers allows reaching expected higher values of fracture energy, but with respect to results of compressive and flexural strength determination as an optimal rate of basalt fibers dose was considered 0.25% in volume. Fine ground ceramic powder application led to extensive increase of residual mechanical parameters just up to replacement of 10%. Higher replacement of aluminous cement reduced final values of bulk density but kept mechanical properties on the level of mixtures without aluminous cement replacement.

scholarly journals RESIDUAL PROPERTIES OF FIBER-REINFORCED REFRACTORY COMPOSITES WITH A FIRECLAY FILLER

2016 ◽  
Vol 56 (1) ◽  
pp. 27 ◽  
Author(s):  
Marcel Jogl ◽  
Pavel Reiterman ◽  
Ondřej Holčapek ◽  
Jaroslava Koťátková ◽  
Petr Konvalinka
Keyword(s):  
Bulk Density ◽  
Thermal Loading ◽  
Ceramic Powder ◽  
High Energy ◽  
Mechanical Parameters ◽  
Binder System ◽  
Basalt Fibers ◽  
Residual Properties ◽  
Aluminous Cement ◽  
Residual Values

The aim of our study was to develop a composite material for industrial use that is resistant to the effect of high temperatures. The binder system based on aluminous cement was modified by adding finely-ground ceramic powder and metakaolin to reduce costs and also to reduce adverse effects on the environment due to high energy consumption for cement production. Additives were applied as a partial aluminous cement replacement in doses of 10, 20 and 30% by weight. The composites were evaluated on the basis of their mechanical properties and their bulk density after gradual temperature loading. The influence of basalt fibers and modifications to the binder system were studied at the same time. Basalt fibers were applied in doses of 0.5% and 2.0% by volume. The results confirmed the potential of the mineral additives studied here for practical applications, taking into account the residual mechanical parameters after thermal loading. The addition of ceramic powder reduced the bulk density by 5% for each 10% of cement substitution, but the residual values were very similar. The bulk density and the compressive strength were reduced when basalt fibers were applied, and the flexural strength was significantly increased in proportion to the fiber dosages. Metakaolin seems to be a more suitable additive than the ceramic powder that was applied here, because there was a significant increase in the mechanical parameters and also in the residual values of all properties that were studied.

Use of Materials with Pozzolanic Properties as Partial Cement Replacement in Development of Heat Resistant Composite

2016 ◽  
Vol 827 ◽  
pp. 316-319
Author(s):  
Marcel Jogl ◽  
Jaroslava Koťátková ◽  
Pavel Reiterman
Keyword(s):  
Ceramic Powder ◽  
Partial Replacement ◽  
Structural Elements ◽  
Cement Production ◽  
Cement Replacement ◽  
Binder Component ◽  
Energy Consuming ◽  
Aluminous Cement ◽  
Partial Cement Replacement ◽  
Pozzolanic Properties

Cement is an extremely energy consuming material and its production leads to the emission of a vast amount of greenhouse gases. Cementitious concrete is a universal building material, which is used for the production of various structural elements. The paper describes the problem of cement production and its impact on the environment. This research deals with application of aluminous cement as binder component for the manufacture of refractory composites and with possibilities of further utilization of environmentally friendly materials with pozzolanic properties as a partial replacement of used aluminous cement. These materials are originating as waste in the building industry or by the recycling of cast-off materials. To reduce the costs and adverse effects on the environment was the binder system modified by finely ground ceramic powder and metakaolin. The experimental results present the values of flexural and compressive strength investigated on a series of composite specimens with dimensions of 40×40×160 mm3 and 10, 20 and 30 % of cement replacement. The aim of the present work is to apply the mentioned pozzolanic materials and reach the suitable composite with the sufficient heat resistance and residual mechanical parameters after gradual temperature loading.

Influence of High-Temperature on Polycarboxylate Superplasticizer in Aluminous Cement Based Fibre Composites

2014 ◽  
Vol 982 ◽  
pp. 125-129 ◽  
Author(s):  
Marcel Jogl ◽  
Pavel Reiterman ◽  
Ondřej Holčapek ◽  
Jaroslava Koťátková
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Flexural Strength ◽  
High Temperatures ◽  
Thermal Loading ◽  
Experimental Program ◽  
Basalt Fibers ◽  
Fibre Composites ◽  
Aluminous Cement ◽  
Properties Of Composites

This paper summarizes the results of an experimental program aimed at investigating of the mechanical properties of composites based on aluminous cement for high-temperature applications and deal with the influence of high-thermal loading on polycarboxylate superplasticizing (PCSP) additive contained in the composite. The intent of this examination was caused by the suspicion that the action of high-temperatures can lead to burnout of the PCSP additive and thus subsequently affecting the mechanical properties of the final composite. Silica composites based on Portland cement and silica aggregates are not able to resist the effects of high-temperatures [1]. For high-temperature composites was therefore used aluminous cement Secar®71 (Lafarge S.A.) in combination with crushed basalt aggregates of fraction 0/4 and 2/5 mm. The flexural strength was greatly improved thanks combinations of basalt fibers with lengths of 6.35 mm and 12.7 mm. The values ​​of flexural strength and compression strength were investigated on samples dried at temperature 105 °C or loaded for 180 minutes with high-temperature of 600 °C or 1 000 °C.

Utility of Air-Entraining Additive in the Development of Lightweight Alumina-Based Refractories

2020 ◽  
Vol 975 ◽  
pp. 147-152
Author(s):  
Marcel Jogl ◽  
Pavel Reiterman
Keyword(s):  
Mechanical Properties ◽  
Bulk Density ◽  
High Temperatures ◽  
Building Materials ◽  
Chemical Engineering ◽  
Thermal Loading ◽  
Elevated Temperatures ◽  
Aluminous Cement ◽  
The Many ◽  
The Impact

The paper presents the impact of doses of an air-entraining additive on the mechanical properties of a composite based on aluminous cement. The presented data have been selected from the authors’ most recent research, which supports an economic development of a lightweight composite with the ability to withstand elevated temperatures of up to 1000 °C. The interest in the behaviour of concrete at high temperatures mainly results from the many cases of fires taking place in buildings, high-rises, tunnels, and drilling platform structures. Operation at high temperatures is also of fundamental importance to many major sectors of industry, including material production and processing, chemical engineering, power generation and more. Concrete has a great intrinsic behaviour when exposed to fire, especially when compared to other building materials. However, its fire resistance should not be taken for granted and proper structural fire protection is certainly necessary, e.g. in the form of high-temperature barriers. For the purposes of this experiment, the specimens were composed of cement paste and an air-entraining additive dosage between 2 – 10 % by weight of the cement dose. The properties of investigated specimens, dried at a temperature of 105 °C, were compared with each other. Values of compressive strength, flexural strength, and bulk density are measured in this work. The purpose was to evaluate the effects of the air-entraining agent on the workability of a fresh mixture, its bulk density, and mechanical properties after drying. In the case of a mixture with added short basalt fibres, the effects after high thermal loading were also evaluated. The proposed composites with air-entraining additive over 8 % shown the values of bulk density below 1800 kg/m3, along with the satisfactory strength results.

scholarly journals APPLICABILITY OF CARBON FIBRES IN REFRACTORY CEMENT COMPOSITES

2018 ◽  
Vol 58 (6) ◽  
pp. 346-354
Author(s):  
Ondřej Holčapek ◽  
Pavel Reiterman ◽  
Petr Konvalinka
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
High Temperatures ◽  
Elevated Temperatures ◽  
Ceramic Powder ◽  
Cement Composite ◽  
Industrial Applications ◽  
Carbon Fibres ◽  
Refractory Cement ◽  
Temperature Levels

The main objective of this article is to present the influence of high temperatures on mechanical properties of advanced refractory cement composite reinforced with carbon fibres. The presented material is suitable for industrial applications and can withstand elevated temperatures up to 1000 °C. The action of high temperatures was investigated on two temperature levels 600 °C and 1000 °C and was compared to reference specimens dried at 105 °C. The carbon fibres with flexural strength of 4100MPa were applied in dosage 0.50 %, 0.75% and 1.00% of the total volume. The second investigated modification was mutual ratio between aluminous cement and fine ceramic powder. The influence of high temperatures was investigated by measuring the bulk density, compressive and flexural strength, dynamic modulus of elasticity and fracture energy; all measured on prismatic specimens 40 × 40 × 160 mm. The workability of fresh mixture was limited by the maximum dosage of carbon fibres in 1% of the total volume. Based on the workability and evaluation of residual mechanical properties after temperature loading, the best was found to be the combination of carbon fibres in dosage of 0.75% by volume.

Refractory Cement Composite Reinforced by Various Types of Fibers

2015 ◽  
Vol 824 ◽  
pp. 173-177 ◽  
Author(s):  
Ondřej Holčapek ◽  
Pavel Reiterman ◽  
Marcel Jogl
Keyword(s):  
Material Science ◽  
Elevated Temperatures ◽  
Refractory Concrete ◽  
Cement Composite ◽  
Basalt Fibers ◽  
Ceramic Fibers ◽  
Basic Premise ◽  
Concrete Production ◽  
Aluminous Cement ◽  
Refractory Cement

Following article deals with experimental investigation of elevated temperatures influence on mechanical properties of refractory cement composite, which seems to be very progressive and interesting field of material science. Specimens 40 x 40 x 160 mm3 were exposed to 600 °C and 1000 °C for three hours. Using of aluminous cement, in this case Secar®71 with70 % of Al2O3, means the basic premise for refractory composites. Natural crushed basalt aggregate of two fractions 0-4 mm and 2-5 mm works as filler. Metakaolin MefistoL05 in amount 225 kg/m3 represents the fine filler, commonly used in refractory concrete production. Ceramic fibers or combination of two lengths of basalt fibers significantly improve the flexural characteristics. The goal of this research is to quantified influence of basalt fibers and ceramic fibers on flexural strength, compressive strength and bulk density of cement composite in high temperature conditions.

Resistance of Refractory Cement Composite to Cyclic Temperature Loading

2016 ◽  
Vol 677 ◽  
pp. 23-28 ◽  
Author(s):  
Ondřej Holčapek
Keyword(s):  
Flexural Strength ◽  
Ceramic Powder ◽  
High Volume ◽  
Cement Composite ◽  
Bending Test ◽  
Loading Cycle ◽  
Highest Weight ◽  
Successful Design ◽  
Aluminous Cement ◽  
Refractory Cement

The aim of this study was to describe mechanical properties decline and macroscopic changes after cyclic thermal load of refractory slabs. Investigated elements were made from refractory cement composite containing natural basalt aggregate, fine ceramic powder, aluminous cement with high volume of Al2O3, different dosage of basalt fibres, water and plasticizer. Slabs with dimension 300 x 200 x 38 mm were exposed to elevated temperature 600 °C for three hours (temperature gradient 10 °C/min) and cooled to laboratory condition. This loading cycle was repeated six times. Tensile characteristics were investigated by bending test with clear span of supports 200 mm. Maximum force and displacement increased with increasing amount of basalt fibres. Maximum flexural strength of slabs corresponded to material characteristics measured on specimens 40 x 40 x 160 mm. Slabs with 1% of basalt fibres achieved flexural strength 4.8 MPa (after six loading cycles). The highest weight decline took place after the first loading cycle. Successful design of original fibre-cement composite has been approved by cyclic loading of larger dimension specimens.

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