Effect of SNCR on the Properties of Fly Ash in Terms of its Applicability to Concrete

2018 ◽  
Vol 272 ◽  
pp. 107-114 ◽  
Author(s):  
Rudolf Hela ◽  
Martin Ťažký
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Fly Ash ◽  
Nitrogen Oxide ◽  
Catalytic Reduction ◽  
Salt Content ◽  
Reduction Process ◽  
Efficiency Index ◽  
Negative Impacts ◽  
The Impact

At the beginning of 2016, the legislation for regulating and reducing the emission of exhaust gases with regard to reducing nitrogen oxides came into force. The articles published to date point to the possibility of increased ammonium salt content in fly ash that has undergone a selective non-catalytic reduction process. This paper addresses other possible negative impacts of the reduction process for nitrogen oxide on the physico-mechanical properties of high-temperature fly ash, especially the morphology of its grains and its impact on the rheology of the composite and the impact on the efficiency index.

Effect of Ammonium Ion Content in Fly Ash after Selective Non-Catalytic Reduction (SNCR) on Physical and Mechanical Properties of Autoclaved Aerated Concrete (AAC)

2018 ◽  
Vol 276 ◽  
pp. 148-153
Author(s):  
Matěj Lédl ◽  
Lucie Galvánková ◽  
Rostislav Drochytka
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Power Plants ◽  
Catalytic Reduction ◽  
Combustion Process ◽  
Ammonium Ion ◽  
Mixing Process ◽  
Autoclaved Aerated Concrete ◽  
Aerated Concrete ◽  
The Impact

After introducing SNCR in coal combustion process in power plants, the valuable by-product such as fly ash remains contaminated with amount of ammonia in form of NH4HSO4, (NH4)2SO4 respectively, which became undesirable in AAC technology because the toxic ammonia is released in the air during the mixing process. This paper deals with the effect of varying ammonia content in fly ash after selective non-catalytic reduction (SNCR) on the physical-mechanical properties of the fly ash based autoclaved aerated concrete (AAC) with the main focus on determination of the impact of the various content of ammonium ion in fly ash on the initial consistency of fresh slurry, the residual content of ammonium ion in hardened aerated matrix and also the impact on the bulk density, compressive strength and tobermorite formation after hydrothermal treatment. Seven batches of AAC, made out of fly ash with rising content of ammonium ion from 0 ppm to 250 ppm, were tested and based on the results obtained it was found out that ammonia is released during the mixing process entirely and doesn‘t remain in AAC after autoclaving, moreover it doesn‘t affect the properties of both fresh slurry (no apparent foaming effect noticed) and thermally treated samples of AAC. Formation of tobermorite wasn’t negatively affected.

scholarly journals Mechanical Properties of Spruce Wood Extracted from GLT Beams Loaded by Fire

2021 ◽  
Vol 13 (10) ◽  
pp. 5494
Author(s):  
Lucie Kucíková ◽  
Michal Šejnoha ◽  
Tomáš Janda ◽  
Jan Sýkora ◽  
Pavel Padevět ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Cross Section ◽  
Negative Impact ◽  
Tensile Tests ◽  
Thermal Recovery ◽  
Bending Test ◽  
Small Scale ◽  
Spruce Wood ◽  
The Impact

Heating wood to high temperature changes either temporarily or permanently its physical properties. This issue is addressed in the present contribution by examining the effect of high temperature on residual mechanical properties of spruce wood, grounding on the results of full-scale fire tests performed on GLT beams. Given these tests, a computational model was developed to provide through-thickness temperature profiles allowing for the estimation of a charring depth on the one hand and on the other hand assigning a particular temperature to each specimen used subsequently in small-scale tensile tests. The measured Young’s moduli and tensile strengths were accompanied by the results from three-point bending test carried out on two groups of beams exposed to fire of a variable duration and differing in the width of the cross-section, b=100 mm (Group 1) and b=160 mm (Group 2). As expected, increasing the fire duration and reducing the initial beam cross-section reduces the residual bending strength. A negative impact of high temperature on residual strength has also been observed from simple tensile tests, although limited to a very narrow layer adjacent to the charring front not even exceeding a typically adopted value of the zero-strength layer d0=7 mm. On the contrary, the impact on stiffness is relatively mild supporting the thermal recovery property of wood.

Research on Barite Concrete Mixed with Fly Ash

2013 ◽  
Vol 275-277 ◽  
pp. 2107-2111
Author(s):  
Qiu Lin Zou ◽  
Jun Li ◽  
Zhen Yu Lai
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Compressive Strength ◽  
High Temperature ◽  
Fly Ash ◽  
Apparent Density ◽  
Cycle Times ◽  
Residual Compressive Strength ◽  
Temperature Performance

Barite concrete with density grade of 3 and strength grade of C30 was prepared by mixing with different fineness of fly ash. The workability, mechanical properties and long-term high temperature performance of the prepared barite concrete were researched. Results show that the workability of barite concrete is improved by mixing with fly ash, and no segregation of mixture has been observed. The apparent density and 3d, 28d compressive strength of barite concrete are decreased obviously after mixing with fly ash. But with the increasing of the fineness of fly ash, the apparent density and 3d, 28d compressive strength of barite concrete have a slight increase. High temperature residual compressive strength is decreased with the increasing of temperature. The cycle times of heat treatment at 400°C only has a little effect on residual compressive strength of barite concrete.

scholarly journals The impact of fly ash and structural fiber on the mechanical properties of concrete

2020 ◽  
Author(s):  
M.D. Ikramullah Khan ◽  
Mohd Abbas Abdy Sayyed ◽  
G. Swamy Yadav ◽  
S. Haripriya Varma
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
The Impact

The Impact of Fly Ash after SNCR Treated with Tannin-Based Products on AAC Production

2019 ◽  
Vol 296 ◽  
pp. 173-179 ◽  
Author(s):  
Matěj Lédl ◽  
Lucie Galvánková ◽  
Rostislav Drochytka
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Bulk Density ◽  
Catalytic Reduction ◽  
Xrd Analysis ◽  
Gaseous Ammonia ◽  
X Ray Diffraction ◽  
Consistency Test ◽  
Effect Of Treatment ◽  
The Impact

This paper is focused on the effect of treatment of fly ash after selective non-catalytic reduction (SNCR) with tannin on autoclaved aerated concrete (AAC) production in order to reduce or stop ammonia leakage from the fresh mixture due to its alkalinity. A pure form of tannin and a tannin-based product „Farmatan“ were used as a treatment in dosage ranging from 0,5 g – 3 g of agent per 1 kg of fly ash. Efficient dosage was determined at 2 wt.% of fly ash by the speed of an indicator change due to gaseous ammonia diluted in water. The rheological properties of fresh mixtures were observed by consistency test in Viskomat showing that Farmatan causes delay of hydration. The results of bulk density and compressive strength testing revealed that Farmatan causes an increase of bulk density and at higher amount decreases the compressive strength because of thermal crack formation due to combined effect of delayed hydration and thixotropy. Using x-ray diffraction (XRD) analysis there were no differences in phase composition observed.

The Suitability of Fly Ash for Use in Concrete According to EN 450 Based on their Particle Size

2018 ◽  
Vol 276 ◽  
pp. 110-115
Author(s):  
Martin Ťažký ◽  
Martin Labaj ◽  
Rudolf Hela
Keyword(s):  
Fly Ash ◽  
Power Plants ◽  
Catalytic Reduction ◽  
Raw Materials ◽  
Thermal Power ◽  
Combustion Process ◽  
Thermal Power Plants ◽  
Mechanical Parameters ◽  
Fly Ashes ◽  
The Impact

The by-products of energy industry are nowadays often affected by new limits governing the production of harmful gases discharged into the air. These stricter and stricter criteria are often met by electricity producers by changing the combustion process in thermal power plants itself. Nowadays, the SNCR (selective non-catalytic reduction) application is quite common in the combustion process in order to help reduce the nitrogen oxide emission. This article deals with the primary measures of thermal power plants, which in particular consist of a modified treatment of raw materials (coal) entering the combustion process. These primary measures then often cause the formation of fly ash with unsuitable fineness for the use in concrete according to EN 450. The paper presents the comparison of the physico-mechanical parameters of several fly ashes with a different fineness values. The primary task is to assess the impact of non-suitable granulometry in terms of EN 450 on the other physico-mechanical parameters of fly ashes sampled within the same thermal power plant. Several fly ashes produced in the Czech Republic and surrounding countries were evaluated in this way.

Investigation of Impact Compressive Mechanical Properties of Sandstone After as well as Under High Temperature

2014 ◽  
Vol 33 (6) ◽  
pp. 585-591 ◽  
Author(s):  
Shi Liu ◽  
Jinyu Xu
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Critical Temperature ◽  
High Temperatures ◽  
Experimental Studies ◽  
Practical Significance ◽  
Temperature Environment ◽  
Shpb Test ◽  
The Impact ◽  
High Temperature Environment

AbstractConducting experimental studies on the impact compressive mechanical properties of rock under the high temperature environment is of both theoretical value and practical significance to understanding the relationship between the rock under the effect of impact loads and the high temperature environment. Based on the Φ100 mm SHPB and the self-developed Φ100 mm high-temperature SHPB test devices, the impact compressive tests on the sandstone, whether cooling after high temperatures or under real-time high temperatures are carried out. As the test results indicate that since the two high-temperature ways of loading are different from each other, the impact compressive properties of sandstone, after as well as under high temperatures, show different variations along with changes in temperature. Under the effect of the same impact loading rate, there exists a clear critical temperature range in the impact compressive mechanical properties of sandstone after high temperature, and, near the critical temperature, there occurs a significant mutation in the impact compressive mechanical properties. Under high temperatures, however, the impact compressive mechanical properties follow an overall continuity of change except that there are slight fluctuations at individual temperatures.

Comparison of Mechanical Properties of Fly Ash Artificial Geopolymer Aggregates with Natural Aggregate

2015 ◽  
Vol 754-755 ◽  
pp. 290-295 ◽  
Author(s):  
Alida Abdullah ◽  
Ku Amirrul Rahman Ku Yin ◽  
Mohd Mustafa Al Bakri Abdullah ◽  
Kamarudin Hussin ◽  
Mien Van Tran
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Specific Gravity ◽  
Water Absorption ◽  
Raw Materials ◽  
Construction Materials ◽  
High Water ◽  
Natural Aggregate ◽  
Materials Used ◽  
The Impact

This study was conducted to compare the mechanical properties of fly ash artificial geopolymer aggregates with natural aggregate (rock) in term of its impact strength, specific gravity and water absorption.The raw materials used were fly ash, sodium hydroxide, sodium silicate and natural aggregate. After the artificial geopolymer aggregate has been produced, its water absorption, specific gravity and aggregate impact test has been done. All results obtained were compared to natural aggregate. The result shows that the fly ash geopolymer aggregate are lighter than natural aggregate in term of its specific gravity. The impact value for fly ash artificial geopolymer aggregate slightly high compared to natural aggregate while it has high water absorption value compared to natural aggregate. As conclusion, the fly ash artificial geopolymer aggregate can be used as one of the construction materials in concrete as an alternative for coarse aggregate besides natural aggregate with more lightweight properties.

Research on Preparation and Properties of New Type Desulfurization Gypsum Block

2014 ◽  
Vol 540 ◽  
pp. 217-220
Author(s):  
Chuan Wei Du ◽  
Ying Lv ◽  
Guo Zhong Li
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Water Resistance ◽  
Experimental Results ◽  
New Type ◽  
Cementing Material ◽  
The Impact

Desulfurization building gypsum was used as the main gelled material and fly ash was used as filler to prepare the new type desulfurization gypsum block. the mechanical properties of the new type desulfurization gypsum block was improved by adding compound excitation agent into the desulphurization gypsum-fly ash cementing material to stimulate its activity. The water resistant performance of the new type desulfurization gypsum block was improved through adding wax-alcohol compound waterproofing agent into it. Experimental results show that when the filling amount of fly ash was 20%(the quality of desulfurization gypsum), the impact on the strength of gypsum was minimal; when the dosage of compound excitation agent was 1.75%, the excitation effect of desulphurization gypsum-fly ash cementing material was best; when the dosage of wax-alcohol compound waterproofing agent was 0.4%, the water resistance of new desulfurization gypsum block was optimal.

Effect of Fly Ash Content on Mechanical Properties of Cement-Fly Ash Stabilized Crushed Stones

2014 ◽  
Vol 548-549 ◽  
pp. 228-232 ◽  
Author(s):  
Xiao Chen ◽  
Ji Wei Liu ◽  
Ming Kai Zhou
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Fly Ash ◽  
Crack Resistance ◽  
Unconfined Compressive Strength ◽  
Resilient Modulus ◽  
Ash Content ◽  
Mechanical Parameters ◽  
Cleavage Strength ◽  
The Impact

To improve the impact of fly ash on the properties of cement-fly ash stabilized crushed stone, and promote it popularize and apply better. This paper investigated the effect of fly ash content on unconfined compressive strength, cleavage strength and resilient modulus of cement-fly ash stabilized crushed stones, and those relationships between mechanical parameters. The results showed that with increasing of the fly ash content, the unconfined compressive strength and cleavage strength increased at first, then decreased, the resilient modulus decreased, and The brittleness index increased. We can conclude that the optimal fly ash content is between 10% and 15%, and increment of fly ash content can improve its crack-resistance.

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