Mechanical and Fracture Characteristics of Refractory Concrete after the Action of Various Temperature Loading

2018 ◽  
Vol 760 ◽  
pp. 102-107
Author(s):  
Ondřej Holčapek
Keyword(s):  
Mechanical Properties ◽  
Experimental Investigation ◽  
Compressive Strength ◽  
Dynamic Modulus ◽  
Thermal Loading ◽  
Refractory Concrete ◽  
Fracture Characteristics ◽  
Residual Properties ◽  
Aluminous Cement ◽  
Refractory Composite

This article deals with the experimental investigation of residual mechanical properties of refractory composite after the action of various thermal loading. Specimens with dimension 40 × 40 × 160 mm were produced from composite containing basalt fibres and aggregate, aluminous cement and metakaolin. Different group of specimens were exposed to various temperatures 105 °C, 200 °C, 300 °C, 400 °C, 500 °C and 600 °C for three hours. Different temperature caused various changes in chemical composition of concrete that can result into decrease of mechanical properties. Bulk density, flexural strength, compressive strength, fracture energy and dynamic modulus of elasticity were investigated after each type of thermal loading. After the action of 600 °C all investigated residual properties achieved lowest values. Based on performed experiments we can conclude that the main decrease of mechanical properties take place after the action of 400 °C.

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.

The Effect of Micronized Waste Marble Powder as Partial Replacement for Cement on Resulting Mechanical Properties of Cement Pastes

2017 ◽  
Vol 1144 ◽  
pp. 54-58
Author(s):  
Zdeněk Prošek ◽  
Karel Šeps ◽  
Jaroslav Topič
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Reference Material ◽  
Dynamic Modulus ◽  
Blended Cement ◽  
Partial Replacement ◽  
Dynamic Shear Modulus ◽  
Dynamic Shear ◽  
Cement Pastes ◽  
Marble Powder

This article was focused on the influence of the micronized waste marble powder on mechanical properties of cement pastes. Resulting blended cement was composed of Portland cement CEM I 42.5 R and micronized marble powder with different percentage amounts (0 wt. %, 5 wt. %, 10 wt. % and 15 wt. %). Testing was carried at prismatic samples of dimension 40 × 40 × 160 mm. The investigated mechanical properties were dynamic modulus of elasticity, dynamic shear modulus, flexural strength and compressive strength for the 28 days old samples. The results obtained from these materials were compared with reference material.

Phase Composition, Microstructure and Mechanical Properties of Aluminous Cements Containing Magnesium Aluminate Spinel

2011 ◽  
Vol 492 ◽  
pp. 467-471
Author(s):  
Jin Hong Li ◽  
Ling Xin Tong ◽  
Wen Cai Zhou
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Phase Composition ◽  
Magnesium Aluminate ◽  
Magnesium Aluminate Spinel ◽  
Curing Time ◽  
Sintering Process ◽  
Microstructure And Mechanical Properties ◽  
New Type ◽  
Aluminous Cement

A new type aluminous cement containing magnesium aluminate (MA) spinel was prepared from mixtures of limestone, magnesian and bauxite at different ratios by sintering process. The phase composition, microstructure and mechanical properties of aluminous cements containing magnesium aluminate spinel were investigated in this paper. According to the XRD results, the magnesium aluminate spinel (MA),calcium monoaluminate (CA) and calcium bialuminate (CA2) are the primary phases of the obtained aluminous cements with a small quantity of calcium silicoaluminate (C2AS) and remained alumina (Al2O3). The results of SEM indicate that the MA mainly exist in the shape of octahedron with the length of about 2-5 μm, and it is agglomerated with the tabular or flaky-shaped CA among the obtained aluminous cements. In addition, the compressive strength of castables containing obtained aluminous cements increase obviously with the content of CA rising or the curing time increasing.

scholarly journals Refractory and Mechanical Properties of Dealuminated Kaoline-Based Geopolymer Concrete

2020 ◽  
Vol 8 (5) ◽  
pp. 2045-2049
Keyword(s):  
Mechanical Properties ◽  
Refractory Concrete ◽  
Geopolymer Concrete ◽  
Thermal And Mechanical Properties ◽  
Concrete Mixtures ◽  
Cold Crushing Strength ◽  
Aluminous Cement ◽  
Shock Resistance ◽  
Alkaline Activator ◽  
Geopolymer Paste

This study has been performed to evaluate the performance of the industrial by-product dealuminated kaolin (DK) as geopolymer paste in production a refractory concrete. The paper study the thermal and mechanical properties of concrete mixtures containing crushed refractory brick as combined aggregate and geopolymer paste produced from the blend of 10%, 20% and 30% of DK, ordinary Portland cement (OPC), solution of sodium hydroxide and sodium silicate as alkaline activator. These concrete mixtures were tested for workability, shrinkage at 400,800 and 1200 °C, thermal shock resistance at temperature of 950 °C, Cold crushing strength, tensile strength, and elastic modulus. The results of these mixtures compared with the results of concrete mixtures containing 100% OPC and 100% aluminous cement (AC) .The results show that the thermal and mechanical properties of geopolymer concrete produced by dealuminated kaolin (DK) are enhanced. Also, it is found that mixture contains 20% of DK appears to be the optimal geopolymer concrete mixture.

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 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.

Experimental Research on New Concrete Air Entraining Agent

2011 ◽  
Vol 194-196 ◽  
pp. 1063-1068
Author(s):  
Bao Min Wang ◽  
Ni Tu
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Dynamic Modulus ◽  
Frost Resistance ◽  
Loss Rate ◽  
Strength Loss ◽  
Weight Loss Rate ◽  
Thaw Cycle ◽  
New Type ◽  
Resistance Durability

Using waste to produce a new type of air entraining agent (AEA), carrying out research of the concrete’s mixture performance, mechanical properties and frost resistance durability after mixing with the AEA, with results showing that amount of air entrained in the concrete mixture and the water reducing rate increases along with the increase of the addition of the new AEA, and its compressive strength loss laws are similar with that of normal AEAs. During the frost-thaw cycle test, when the weight loss rate has reached its limit, concrete with the new AEA added can withstand almost 300 cycles, and at this time the relative dynamic modulus of the concrete, when the amount of air entrained in it is 4.5%, is 83.5%, and the relative dynamic modulus is 85.4% when the amount of air entrained is 5.3%. The addition of the AEA has obviously improved the pore structure of the concrete, and significantly raising its frost resistance durability.

scholarly journals Experimental Investigation on Rcc by Using Multiple Admixtures

2018 ◽  
Vol 7 (3.3) ◽  
pp. 14 ◽  
Author(s):  
Professor P.Venkatreddy ◽  
A Siva Krishna ◽  
G SwamyYadav
Keyword(s):  
Mechanical Properties ◽  
Experimental Investigation ◽  
Compressive Strength ◽  
Silica Fume ◽  
Research Work ◽  
Copper Slag ◽  
Partial Replacement ◽  
Fine Aggregate ◽  
Flexure Strength ◽  
Concrete Properties

In this article, the effect of replacing cement with silica fume and fine aggregate with copper slag has been investigated. For this research work, concrete of M40 grade is prepared and evaluated for fresh and harden concrete properties such as compressive strength, tensile strength and flexural strength. Further, the cement is replaced with silica fume at 0, 2, 4, 6, 8 and 10 % and fine aggregate replaced with copper slag at 0, 10, 20, 30, 40 and 50 %. Compressive strength, strength and Flexure strength have been tested. It is observed from the results that the use of silica fume and copper slag as partial replacement material improves mechanical properties of the concrete. Concrete with 40 % copper slag and 8 % silica fume shows better performance among all the mixes.  

scholarly journals ASSESSMENT OF MIX PROPORTIONS FOR DEVELOPING LIGHTWEIGHT CEMENTITIOUS COMPOSITES WITH WOOD WASTES

2017 ◽  
Vol 41 (1) ◽  
Author(s):  
Monica Garcez ◽  
Estela Garcez ◽  
Aline Machado ◽  
Darci Gatto
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Water Absorption ◽  
Bulk Density ◽  
Modulus Of Elasticity ◽  
Dynamic Modulus ◽  
Void Ratio ◽  
Eucalyptus Grandis ◽  
Cementitious Composites ◽  
Wood Composites

ABSTRACT The main objective of this work was to assess mix proportions for developing lightweight cementitious composites, manufactured with Eucalyptus grandis sawdust. Different wood:cement, water:cement and admixture:cement ratios were used to evaluate physical (water absorption, void ratio and density) and mechanical (compressive strength, static and dynamic modulus of elasticity) properties of the cement-wood composites. Results shows that, bulk density is directly proportional to the compressive strength and elastic modulus, and inversely proportional to the percentage of timber, considering composites with same water:cement ratio, without superplasticizer. The performance of the cement-wood composites, regarding mechanical properties, can be improved if superplasticizer is used to increase paste fluidity. Higher values of bulk density are related to lower void ratio and water absorption and higher compressive strength and modulus of elasticity.

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