scholarly journals Composites Based on Alternative Raw Materials at High Temperature Conditions

2017 ◽  
Author(s):  
Tomáš Melichar ◽  
Jiří Bydžovský ◽  
Ámos Dufka
Keyword(s):  
High Temperature ◽  
Fly Ash ◽  
Composite Structures ◽  
Raw Materials ◽  
Analytical Techniques ◽  
Temperature Changes ◽  
Dimensional Changes ◽  
Transition Zones ◽  
The Matrix ◽  
Positive Effect

This paper presents newly developed polymer-cement composites.The primary binder (cement) was partially substituted byuse of blast-furnace slag and high-temperature fly ash. A lightweightaggregate – agloporite (grain size in range 1–2 mm) wasused among other components. This porous aggregate is producedfrom energy by-products (fly ash). Attention was focusedon the behavior of the composites when exposed to elevatedtemperatures (400 °C–1,000°C). The influence of several differentmethods of temperature decrease was assessed – slow(in furnace 1°C/min) and rapid (laboratory ambient 22°C andwater bath 18°C). Specific dimensional changes were determined,including strength characteristics and bulk density.Structural deterioration and microstructural changes of selectedspecimens were investigated by analytical techniques (SEM andCT). Compressive and bending tensile strength changed variouslydepending on temperature changes, including severalcooling conditions. Deterioration reactions (especially cracks)which were formed in investigated composite structures correspondedwith results of physico-mechanical testing. That wasconfirmed by using the CT and SEM.The fact that the agloporite has a positive effect on thermalresistance of developed polymer-cement composites wasproved. Almost no cracks or other failures were identified (byusing CT and SEM) in interfacial transition zones of agloporiteafter thermal stress. This indicates very good bond adhesionbetween the matrix and the porous aggregates during extremetemperature conditions (in case of different cooling methods).

Influence of Fly Ash on Corrosion Resistance of Refractory Forsterite-Spinel Ceramics

2021 ◽  
Vol 325 ◽  
pp. 181-187
Author(s):  
Martin Nguyen ◽  
Radomír Sokolář
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Corrosion Resistance ◽  
Fly Ash ◽  
Raw Materials ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transition Zones ◽  
Refractory Ceramics ◽  
Scanning Electron

This article examines the influence of fly ash on corrosion resistance of refractory forsterite-spinel ceramics by molten iron as a corrosive medium. Fly ash in comparison with alumina were used as raw materials and sources of aluminium oxide for synthesis of forsterite-spinel refractory ceramics. Raw materials were milled, mixed in different ratios into two sets of mixtures and sintered at 1550°C for 2 hours. Samples were characterized by X-ray diffraction analysis and thermal dilatometric analysis. Crucibles were then made from the fired ceramic mixtures and fired together with iron at its melting point of 1535°C for 5 hours. The corrosion resistance was evaluated by scanning electron microscopy on the transition zones between iron and ceramics. Mixtures with increased amount of spinel had higher corrosion resistance and mixtures with fly ash were comparable to mixtures with alumina in terms of corrosion resistance and refractory properties.

scholarly journals Green Sound-Absorbing Composite Materials of Various Structure and Profiling

Coatings ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 407
Author(s):  
Eulalia Gliscinska ◽  
Javier Perez de Amezaga ◽  
Marina Michalak ◽  
Izabella Krucinska
Keyword(s):  
Sound Wave ◽  
Sound Absorption ◽  
Raw Materials ◽  
Matrix Material ◽  
Composite Layer ◽  
Renewable Raw Materials ◽  
Flax Fibers ◽  
The Matrix ◽  
Reinforcing Material ◽  
Positive Effect

This article presents thermoplastic sound-absorbing composites manufactured on the basis of renewable raw materials. Both the reinforcing material and the matrix material were biodegradable and used in the form of fibers. In order to mix flax fibers with polylactide fibers, the fleece was fabricated with a mechanical system and then needle-punched. The sound absorption of composites obtained from a multilayer structure of nonwovens pressed at different conditions was investigated. The sound absorption coefficient in the frequency ranging from 500 Hz to 6400 Hz was determined using a Kundt tube. The tests were performed for flat composites with various structures, profiled composites, and composite/pre-pressed nonwoven systems. Profiling the composite plate by convexity/concavity has a positive effect on its sound absorption. It is also important to arrange the plate with the appropriate structure for the incident sound wave. For the composite layer with an added pre-pressed nonwoven layer, a greater increase in sound absorption occurs for the system when a rigid composite layer is located on the side of the incident sound wave. The addition of successive nonwoven layers not only increases the absorption but also extends the maximum absorption range from the highest frequencies towards the lower frequencies.

Silicate Sprayed Mixture Based on Secondary Raw Materials

2019 ◽  
Vol 808 ◽  
pp. 129-135
Author(s):  
Petr Figala ◽  
Rostislav Drochytka ◽  
Radek Hermann ◽  
Jiří Kolísko
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
High Temperature ◽  
Fly Ash ◽  
Raw Materials ◽  
Positive Influence ◽  
Foundry Sand ◽  
Secondary Raw Materials ◽  
Fundamental Research

This paper studies the fundamental research and development of sprayed cement-based mixture designed to withstand the chemically aggressive conditions. The aim of this paper is to verify the possibilities of usage of suitable secondary raw materials as a substitution of a binder and filler of the original mixture while preserving or improving the physical-mechanical properties. In this part of the research was studied the possibility to substitute the binder in rate of 20-60 wt.% by high temperature fly ash and the whole filler by foundry sand and slag. Test samples were made from nine recipes, in which was monitored the influence of secondary raw materials on the compressive strength and the water absorption after 28 days of curing. The results of this paper show, it is possible to successfully substitute part of the binder by high temperature fly ash and the filler wholly by foundry sand in the sprayed mixture. These optimized recipes showed positive influence mainly in the long-term on mechanical properties.

scholarly journals Effect of High Temperature on Mechanical Properties of Geopolymer Mortar

2018 ◽  
Vol 163 ◽  
pp. 06004 ◽  
Author(s):  
Mateusz Sitarz ◽  
Izabela Hager ◽  
Joanna Kochanek
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Fly Ash ◽  
Cement Mortar ◽  
Raw Materials ◽  
Thermal Exposure ◽  
Amorphous Structure ◽  
Secondary Mineral ◽  
Mineral Raw Materials ◽  
Interesting Alternative

The advent of modern aluminosilicate binders has resulted in practical uses for fly ash, which belongs to the group of secondary mineral raw materials; this provides an interesting alternative to cementitious binders, which have a large carbon footprint. Geopolymers mineral binders with a growing range of applications in construction. Their inorganic, amorphous structure endows them with better resistance to high temperature compared to cementitious binders. In this study, the alkaline activation of aluminosilicate Połaniec Fly Ash made it possible to obtain noncementitious material with compressive strength of 18.5 MPa. The article presents the results of a comparison of characteristics of geopolymer mortar and Portland cement mortar after thermal exposure.

POSSIBILITIES OF DETERMINATION OF OPTIMAL DOSAGE OF POWER PLANT FLY ASH FOR CONCRETE

2016 ◽  
Vol 78 (5-3) ◽  
Author(s):  
Rudolf Hela ◽  
Martin Tazky ◽  
Lenka Bodnarova
Keyword(s):  
High Temperature ◽  
Fly Ash ◽  
Partial Replacement ◽  
Optimal Dosage ◽  
Test Results ◽  
Temperature Combustion ◽  
High Production ◽  
Positive Effect ◽  
High Temperature Combustion

The paper describes possibilities of making use of high temperature combustion fly ash for production of concrete more effective. Efforts for maximal utilization of high temperature combustion fly ash are supported by high production of fly ash worldwide. Use of high temperature fly ash for concrete has to take into account considerably lower speed of hydration reactions compared to pure Portland cement. The paper states results of experimental determination of optimal dosage of fly ash as partial replacement of cement. Dosage of fly ash for production of concrete was optimized. Test results proved positive effect of dosage of fly ash with respect to granulometry of used cement and fly ash. Taking granulometry of fly ash and cement into consideration improves physico-mechanical properties of concrete compared to concrete with fly ash designed standardly without considering granulometry. 

Raw Materials Analysis by XRF in the Cement Industry

1992 ◽  
Vol 36 ◽  
pp. 139-144
Author(s):  
Sona H. Babikian
Keyword(s):  
Fly Ash ◽  
Raw Materials ◽  
Coal Fly Ash ◽  
Coal Ash ◽  
Analytical Techniques ◽  
Major Elements ◽  
Cement Industry ◽  
Industrial Wastes ◽  
Standard Reference Materials ◽  
Materials Used

AbstractThe sources of raw materials used in the manufacture of Portland cement include pure to argillaceous limestones, shale and clay, plus minor quantities of sand, iron ore, fly ash, coal ash and suitable industrial wastes. To ensure a high quality product, rapid - precise - reproducible and practical analytical techniques are required. Quantitative XRF analysis techniques meet those demands.For this comparative technique, the instrument used is a wavelength dispersive sequential spectrometer. The advantages and the drawbacks of the technique are discussed, along with the procedure of the specimen fused bead preparation. The importance of calibration standards and unknown samples being prepared in an identical manner, and being presented to the instrument under similar conditions, is stressed. International and synthetic standards, concentration ranges for the five major elements, mathematically generated coefficients to correct absorption and enhancement effects, and a summary of the standard error of estimates are examined and discussed.The accuracy of the method is verified by the analysis of known standard reference materials such as obsidian rock, coal fly ash, argillaceous limestone and blastfurnace slag. The values are compared with the known certified values.

Lightweight Mortar Containing High Amounts of Alternative Raw Materials with Increased Thermal Resistance

2018 ◽  
Vol 916 ◽  
pp. 190-194
Author(s):  
Tomáš Melichar ◽  
Jiří Bydžovský ◽  
Ámos Dufka
Keyword(s):  
Fly Ash ◽  
Raw Materials ◽  
Lightweight Aggregate ◽  
Strength Properties ◽  
Physical Chemical ◽  
Chemical Phase ◽  
Alternative Materials ◽  
The Matrix ◽  
Lightweight Mortar ◽  
Heating Plant

The paper researches lightweight mortars based on a high content of alternative materials. 25 – 30% heating plant slag was used in order to modify the matrix. Fly ash agloporite (a lightweight aggregate produced by self-combustion from fly ash) was used as an aggregate. Mortars were exposed to the temperatures up to 1,250° C. Two types of cooling were carried out at 1,000° C; controlled slow (in the furnace) and by shock (in water baths of approximate 18° C). Developed materials were further analyzed by various methods: monitoring changes in an observation furnace, physical–mechanical (to determine strength properties), physical-chemical (phase composition - XRD) and microstructural (SEM).

High Temperature Properties of Geopolymeric Ceramic

2008 ◽  
Vol 368-372 ◽  
pp. 1529-1531
Author(s):  
Yi Hai Jia ◽  
Min Fang Han ◽  
Ze Sheng Xu ◽  
Yan Gao ◽  
Xian Xian Meng
Keyword(s):  
Weight Loss ◽  
Compressive Strength ◽  
Thermal Properties ◽  
High Temperature ◽  
Fly Ash ◽  
High Temperatures ◽  
Room Temperature ◽  
Raw Materials ◽  
High Temperature Properties ◽  
Alkaline Activator

With fly ash, metakaolin, slag and alkaline activator as raw materials, the geopolymeric ceramic was synthesized and the properties, such as the weight loss, compressive strength and the structures, at high temperatures of 400~1200°C were measured. The weight loss is in the range of 8~13% from 400°C to 800°C. Comparing with the strength at room temperature, the compressive strength of samples is mostly increased at 400°C and all of them increased at 800°C. 9.65~28.32% strength declines at 1200°C. The variation of the compressive strength with temperature is explained based on the analyses of the phases constitutes and the thermal properties of samples.

scholarly journals OPTIMIZATION OF MIX-DESIGN OF CHEMICALLY RESISTANT SPRAYED CONCRETE

2019 ◽  
Vol 22 ◽  
pp. 26-30
Author(s):  
Radek Hermann ◽  
Rostislav Drochytka ◽  
Jiří Kolísko ◽  
Pavel Reiterman
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Fly Ash ◽  
Chemical Resistance ◽  
Raw Materials ◽  
Waste Glass ◽  
Mix Design ◽  
Sprayed Concrete ◽  
Secondary Raw Materials ◽  
Soluble Glass

This paper addresses optimization of mix-design and granulometric curves of aggregate of chemically resistant cementitious sprayed mix. The target of the paper is to improve properties of currently developed mix-design, which has no chemical resistance, and to utilize the secondary raw materials. The mix was optimized by additions improving chemical resistance and binder substituted by secondary raw materials. The binder was substituted by finely ground waste glass and high-temperature fly ash. Filler was substituted with slag from deposit yard and waste sand with soluble glass from steel manufacture. Main observed properties for design of optimized mix were workability time, consistence and physical-mechanical properties. Optimized mix-design successfully replaced all fine parts of filler and up to 30% of binder while the physical-mechanical properties were preserved or even enhanced. Optimized mix-designs show the same consistencies and workability times.

Effect of High Temperature on Wear Behavior of Stir Cast Aluminium/Boron Carbide Composites

2020 ◽  
Vol 22 (4) ◽  
pp. 1031-1046
Author(s):  
X. Canute ◽  
M. C. Majumder
Keyword(s):  
High Temperature ◽  
Wear Rate ◽  
Boron Carbide ◽  
Wear Behavior ◽  
Base Alloy ◽  
Weight Fraction ◽  
Sliding Velocity ◽  
Wear Properties ◽  
High Temperature Wear ◽  
The Matrix

AbstractThe need for development of high temperature wear resistant composite materials with superior mechanical properties and tribological properties is increasing significantly. The high temperature wear properties of aluminium boron carbide composites was evaluated in this investigation. The effect of load, sliding velocity, temperature and reinforcement percentage on wear rate was determined by the pin heating method using pin heating arrangement. The size and structure of base alloy particles change considerably with an increase of boron carbide particles. The wettability and interface bonding between the matrix and reinforcement enhanced by the addition of potassium flurotitanate. ANOVA technique was used to study the effect of input parameters on wear rate. The investigation reveals that the load had higher significance than sliding velocity, temperature and weight fraction. The pin surface was studied with a high-resolution scanning electron microscope. Regression analysis revealed an extensive association between control parameters and response. The developed composites can be used in the production of automobile parts requiring high wear, frictional and thermal resistance.

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