scholarly journals Influence of the Variability of Calcareous Fly Ash Properties on Rheological Properties of Fresh Mortar with Its Addition

Materials ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 1942 ◽  
Author(s):  
Artur Nowoświat ◽  
Jacek Gołaszewski
Keyword(s):  
Fly Ash ◽  
Bulk Density ◽  
Rheological Properties ◽  
Coefficient Of Variation ◽  
Negative Impact ◽  
Concrete Technology ◽  
Mineral Additive ◽  
Main Component ◽  
The Impact ◽  
By Products

One of the main by-products of brown coal burning is calcareous fly ash (CFA). Apart from other applications, it is used as a main component of cement, or as an active mineral additive to concrete. The present study involves the impact of the raw and processed calcareous fly ash (CFA) on the changes of rheological properties of mortars. The said impact was determined by using the coefficient of variation (CV) given in percentage. CFA samples collected from various sources were subjected to testing. The samples were collected from two electrofilters of blocks with boilers of different combustion parameters and from the retention tanks of the CFA sales department (CFA T) in which CFAs from various boilers are mixed. It has been demonstrated that the degree of the impact of CFA addition on the rheological properties of mortars depends on the source of this addition and on bulk density. The present work demonstrates the negative impact of raw CFA on mortar workability, and hence it is questionable to support its use in concrete technology.

scholarly journals Polyphenol Profiling of Chestnut Pericarp, Integument and Curing Water Extracts to Qualify These Food By-Products as a Source of Antioxidants

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2335
Author(s):  
Gabriella Pinto ◽  
Sabrina De Pascale ◽  
Maria Aponte ◽  
Andrea Scaloni ◽  
Francesco Addeo ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Negative Impact ◽  
Tap Water ◽  
Time Of Flight ◽  
The Other ◽  
Curing Process ◽  
Flight Mass Spectrometry ◽  
Water Curing ◽  
The Impact ◽  
By Products

Plant polyphenols have beneficial antioxidant effects on human health; practices aimed at preserving their content in foods and/or reusing food by-products are encouraged. The impact of the traditional practice of the water curing procedure of chestnuts, which prevents insect/mould damage during storage, was studied to assess the release of polyphenols from the fruit. Metabolites extracted from pericarp and integument tissues or released in the medium from the water curing process were analyzed by matrix-assisted laser desorption ionization-time of flight-mass spectrometry (MALDI-TOF-MS) and electrospray-quadrupole-time of flight-mass spectrometry (ESI-qTOF-MS). This identified: (i) condensed and hydrolyzable tannins made of (epi)catechin (procyanidins) and acid ellagic units in pericarp tissues; (ii) polyphenols made of gallocatechin and catechin units condensed with gallate (prodelphinidins) in integument counterparts; (iii) metabolites resembling those reported above in the wastewater from the chestnut curing process. Comparative experiments were also performed on aqueous media recovered from fruits treated with processes involving: (i) tap water; (ii) tap water containing an antifungal Lb. pentosus strain; (iii) wastewater from a previous curing treatment. These analyses indicated that the former treatment determines a 6–7-fold higher release of polyphenols in the curing water with respect to the other ones. This event has a negative impact on the luster of treated fruits but qualifies the corresponding wastes as a source of antioxidants. Such a phenomenon does not occur in wastewater from the other curing processes, where the release of polyphenols was reduced, thus preserving the chestnut’s appearance. Polyphenol profiling measurements demonstrated that bacterial presence in water hampered the release of pericarp metabolites. This study provides a rationale to traditional processing practices on fruit appearance and qualifies the corresponding wastes as a source of bioactive compounds for other nutraceutical applications.

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.

scholarly journals The Durability of Concrete Modified by Waste Limestone Powder in the Chemically Aggressive Environment

Materials ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1693 ◽  
Author(s):  
Maja Kępniak ◽  
Piotr Woyciechowski ◽  
Paweł Łukowski ◽  
Justyna Kuziak ◽  
Rafał Kobyłka
Keyword(s):  
Negative Impact ◽  
Raw Materials ◽  
Desirability Function ◽  
Chloride Ion ◽  
Production Costs ◽  
Limestone Powder ◽  
Fine Aggregate ◽  
Concrete Technology ◽  
The Impact ◽  
Durability Of Concrete

The idea of sustainable development assumes that natural resources must be treated as limited goods and that waste must be managed rationally. This idea and the constant striving to reduce production costs make the use of waste materials as substitutes for traditionally used raw materials from non-renewable sources increasingly popular. In cement concrete technology, there are many possibilities to use waste as components of mortars and concretes. The subject of this paper is a fine-grained material, obtained as a by-product during the preparation of aggregate for mineral-asphalt mixtures. The aim of the research was to test the suitability of the selected type of powder, namely limestone powder, as a component of cement composites. The paper presents an evaluation of the potential of using the limestone powder as a substitute for the fine aggregate, focusing on the impact of such a modification on aspects of durability. The sulfate degradation and chloride ion diffusion in concrete were investigated. The overall desirability function has been determined. It was demonstrated that the satisfactory value of the general desirability can be attributed to most of the investigated concretes. Positive test results support the potential of replacing part of natural fine aggregate with the tested waste limestone dust without a negative impact on the durability of concrete.

scholarly journals Rheodynamic Concrete as a Progressive Viability in the field of Concrete Technology

2020 ◽  
Vol 9 (3) ◽  
pp. 319-327
Keyword(s):  
Fly Ash ◽  
Rice Husk Ash ◽  
Construction Material ◽  
Working Environment ◽  
Construction Work ◽  
Self Compacting Concrete ◽  
Concrete Technology ◽  
The World ◽  
By Products ◽  
Safe Working

The most important material which is used for the construction of any concrete structure is concrete itself. It is considered to be as a versatile construction material as its properties can be changed by various means, with the help of different elements and as and when required. Rheodynamic Concrete or Self-Compacting Concrete is a special form of concrete which can easily flow into any kind of formwork uniformly, without facing the problem of bleeding and segregation, gives a better finish, has a great characteristic of placement, requires no vibration, and thus gives a safe working environment. Due to a number of merits, this type of concrete had becoming popular in the construction work. Simultaneously, the big industries across the world are producing the by products such as fly ash, rice husk ash, etc. Thus, this paper represents a review, which is done to incorporate these wastes by – products in Self-Compacting Concrete and observe, how the different properties of the same has been modified effectively and efficiently.

scholarly journals The impact of phacoemulsification on corneal endothelial cells in patients with pseudoexfoliation syndrome

2019 ◽  
Vol 12 (1) ◽  
pp. 50-55
Author(s):  
V. V. Potemkin ◽  
T. S. Varganova ◽  
E. V. Ageeva
Keyword(s):  
Endothelial Cells ◽  
Endothelial Cell ◽  
Coefficient Of Variation ◽  
Negative Impact ◽  
Corneal Endothelial Cell ◽  
Pseudoexfoliation Syndrome ◽  
Corneal Endothelial Cells ◽  
Before And After ◽  
Corneal Endothelial Cell Density ◽  
The Impact

The effect of pseudoexfoliation syndrome (PEХ) on endothelial cells has been studied long enough. Yet the effect of phacoemulsification (PHACO) on endothelium in patients with PEХ is less explored.Purpose. To assess the impact of PHACO on corneal endothelial cell density (ECD) and on the coefficient of variation (CV) in patients with PEX.Material and methods. 30 patients (30 eyes) with PEX syndrome and 34 patients (34 eyes) with no such syndrome were examined before and after phacoemulsification.Results. In patients with PEX, the ECD after PHACO was significantly lower and CV was significantly higher (р < 0.05).Conclusion. PEX has a negative impact on endothelial cells, which leads to a pronounced cells loss after PHACO.

The removal of As(V) ions by lime-modified fly ash and reuse of the exhausted adsorbent as an additive for construction material

2020 ◽  
Author(s):  
Milica Karanac ◽  
Maja Đolić ◽  
Vladimir Pavićević ◽  
Aleksandar Marinković
Keyword(s):  
Fly Ash ◽  
Power Plants ◽  
Low Cost ◽  
Construction Material ◽  
Thermal Power ◽  
Construction Materials ◽  
Practical Applications ◽  
The Impact ◽  
By Products ◽  
Modified Fly Ash

&lt;p&gt;Coal thermal power plants (TPP) actively generate numerous solid combustion by-products, including fly ash and bottom ash. These TPP by-products have already found use in a variety of civil engineering applications, such as a substitute for sand and gravel in structures, as well as a binding component in certain types of cement (generally, concrete and masonry). Furthermore, such by-products have become a subject of increasing interest in environmental engineering as a low-cost and effective adsorbent for the removal of organic pollutants and heavy metals from wastewaters.&lt;/p&gt;&lt;p&gt;In order to minimize the impact of material cost, novel solutions for the development of a high capacity and long-term adsorbent have provided a high performance adsorbent for practical applications. This study is focused on the use of modified fly ash (MFA) activated by lime (Ca(OH)&lt;sub&gt;2&lt;/sub&gt;) as an effective and low-cost adsorbent for the removal of As(V) ions. The adsorption capacity of the MFA adsorbent was found to be 35.40 mg g&lt;sup&gt;-1&lt;/sup&gt;, while the kinetic and thermodynamic parameters indicated a spontaneous and endothermic process. Due to the low desorption potential of the exhausted adsorbent (MFA/As(V), their effective further material reuse was established to be feasible. The reuse of the exhausted adsorbent was obtained through pozzolanic MFA particles and Ca(OH)&lt;sub&gt;2, &lt;/sub&gt;thereby formulating a construction material of a cementitious calcium-silicate hydrate. The toxicity leaching test (TCLP) and mechanical properties of the new construction material containing exhausted MFA (CM-MFA/As(V)) confirm its safe use in the laboratory as well as its semi-industrial application.&lt;/p&gt;&lt;p&gt;The specific objectives of this study have been: (i) to improve the adsorption performance of the MFA; (ii) to evaluate the material&amp;#8217;s equilibrium, as well as the process&amp;#8217; kinetic and thermodynamic aspects, including &amp;#160;estimating its limiting step; and (iii) to investigate the possible reuse of the exhausted adsorbent in the production of construction materials. The kinetic data were successfully fitted by a pseudo-second-order equation and the Weber-Morris model. The metal-desorption experiments performed on the exhausted FA and MFA indicate a low recovery of the selected pollutants.&lt;/p&gt;&lt;p&gt;The major outcome of this study, indicates that double-valorization of fly ash opens new directions for waste management toward reuse in effective practical applications; i.e., for actual water &amp;#8211;purification systems, as well as in the production of construction material.&lt;/p&gt;

scholarly journals Effect of plasticizers, superplasticizers and silica fly ash on concrete water-resistance

2016 ◽  
Vol 7 (3) ◽  
pp. 33-38
Author(s):  
Mohamed Ahmad
Keyword(s):  
Fly Ash ◽  
Water Resistance ◽  
Construction Materials ◽  
Poor Quality ◽  
Laboratory Research ◽  
Hardened Concrete ◽  
Fine Aggregate ◽  
Mineral Additive ◽  
The Impact ◽  
Mineral Additives

Concrete is one of the basic construction materials. It is a composite made of cement, water, coarse and fine aggregate. In the past, concrete was produced only with primary components, and it was often of poor quality. Nowadays, technological progress and scientific research allowed the concrete to be made with the use of chemical admixtures and mineral additives to modify and improve selected properties of both the concrete mixture and hardened concrete. Contrary to popular belief, obtaining concrete with suitable properties is not simple and the choice of mixture components requires professional knowledge. The care and quality is also extremely important. The paper presents the results of laboratory research concerning the impact of the plasticizer admixture—Betocrete-C17 and superplasticizer—Arpoment-O and mineral additive of silica fly ash on concrete water resistance. Capillarity, water permeability and water absorption of the concrete were determined. Additionally, a study of the consistency of fresh mixture was done and the hardened concrete compressive strength was tested.

scholarly journals Experimental Study of the Resistance to Influence of Aggressive Liquids on Lightweight Concrete

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4185
Author(s):  
Marzena Kurpińska ◽  
Elżbieta Haustein
Keyword(s):  
Fly Ash ◽  
Lightweight Concrete ◽  
Negative Impact ◽  
Strong Acid ◽  
Weak Acid ◽  
Aqueous Salt Solution ◽  
Mineral Additive ◽  
Foamed Glass ◽  
One Year ◽  
Traditional Construction

In light of the scientific research, the corrosion of concrete structures is one of the main problems that may reduce their durability due to the negative impact of the natural environment. The paper analyzes the influence of the type of component on the selected properties of lightweight concrete subjected to the influence of aggressive liquids. Four concrete mixes were prepared with a granular aggregate made of foamed glass (GEGA) and aggregate made of sintered fly ash (GAA) with the use of a mineral additive: silica fly ash. The prepared lightweight concrete after one year was exposed for 60 days to the following environments: strong acid—HCl, 1% and 2% concentration, weak acid—CH3COOH, 1% and 2% concentration, and an aqueous salt solution of Na2SO4, 1% and 2% concentration. Then, the compressive strength was tested, and the microstructure analysis of the ready-made lightweight concrete (LWC) was performed. The degree of penetration of aggressive solutions into the cracks of the samples was assessed by means of applying 1% phenolphthalein solution. Changes in the weight of lightweight concrete samples after the test period were estimated. The obtained test results indicate that the decrease in the durability of lightweight concrete can be classified as a long-term process. Concrete with GEGA and GAA showed high resistance to aggressive environments. Moreover, the environment containing chlorides turned out to be the most aggressive, while the environment containing sulfates proved to be the least aggressive. The higher the concentration of the destructive factor was, the faster the corrosion process went. This has been proven by measuring the pH using phenolphthalein and carrying out microscopic examination. Concretes containing aggregates made of foamed glass and sintered fly ash are suitable for use both in traditional construction and in facilities exposed to an aggressive environment (e.g., in the chemical industry and at gas stations).

Influence of the Fly Ash Character on Quality of Artificial Aggregate

2015 ◽  
Vol 1124 ◽  
pp. 170-176
Author(s):  
Vit Cerný
Keyword(s):  
Fly Ash ◽  
Building Materials ◽  
Raw Material ◽  
Fly Ashes ◽  
Temperature Combustion ◽  
Combustion Technology ◽  
The Impact ◽  
By Products ◽  
High Temperature Combustion

In a world is of ever-increasing pressure on the use of fly ash in building materials. Despite these efforts the majority of produced energy by-products end up as reclamation material and only small part as high-quality materials. Technology of sintered artificial aggregate is fully based on the fly ashes and allows processing a high percentage of this raw material. The work is devoted to assessing the impact of fly ash character on the quality artificial aggregate. There were selected three fly ashes from high-temperature combustion technology and two from the FBC combustion. The results clearly show that the FBC ashes are not too useful for sintered aggregate technology. For fly ashes is determined primarily by their fineness and the amount of amorphous silica phase.

scholarly journals Impact of admixtures used in underwater concrete on cement hydration process and rheological properties

2020 ◽  
Vol 322 ◽  
pp. 01030
Author(s):  
Aneta Matuszek-Chmurowska ◽  
Alina Kaleta-Jurowska ◽  
Krystian Jurowski ◽  
Stefania Grzeszczyk
Keyword(s):  
Rheological Properties ◽  
Cement Hydration ◽  
Setting Time ◽  
Nano Particles ◽  
Hydration Process ◽  
Rheological Parameters ◽  
Concrete Technology ◽  
Combined Application ◽  
Underwater Concrete ◽  
The Impact

This paper presents test results of the impact of chemical admixtures used in the underwater concrete technology, i.e. a superplasticizer (SP), an anti-wash admixture (AWA) and SiO2 nano- particles (NP) on the cement hydration process, rheological properties and the setting time. The impact of admixtures was tested in combination and separately, with the use of microcalimetry, X-ray diffraction (XRD) and rheology. It was demonstrated that AWA and SP admixtures caused a delay of the hydration process, while the impact of SP was much greater. The above statement was also confirmed by results of rheological tests. Combined application of AWA, SP and NP causes even a larger delay of the hydration process and the increase of paste rheological parameters, with the impact of the superplasticizer particularly visible.

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