Effect of Crystallization Additives on Durability of Cement Composites in Aggressive Environments

2021 ◽  
Vol 321 ◽  
pp. 89-96
Author(s):  
Ámos Dufka ◽  
Šárka Keprdová ◽  
Tomáš Melichar
Keyword(s):  
Acid Solution ◽  
Cement Composites ◽  
Porous Structures ◽  
Chemical Analyses ◽  
Inorganic Acid ◽  
Self Compacting Concrete ◽  
Physical Chemical

This article analyses the effect of crystallization additives on the long-term durability of self-compacting concretes (SCCs) in relation to specific types of chemically aggressive environments. The effect of both an inorganic acid solution and the aggressive solutions produced during plant ensilage were tested, while the effect of diesel on these modified concretes was also investigated. Attention was given to the effect of crystallization additives on the characteristically capillary porous structures of self-compacting concrete, specifically in terms of the long-term durability of SCCs in relation to the above-stated chemically aggressive solutions. The effect of aggressive environments was evaluated through a set of physical-mechanical trials and physical-chemical analyses.

Evaluation of the Effect of Crystallization Additives on the Durability of Cement Composites

2017 ◽  
Vol 908 ◽  
pp. 15-20 ◽  
Author(s):  
Ámos Dufka ◽  
Tomáš Melichar
Keyword(s):  
Service Life ◽  
Porous Structure ◽  
Comprehensive Analysis ◽  
Cement Composites ◽  
Chemical Analyses ◽  
Self Compacting Concrete ◽  
Physico Chemical

The paper deals with a comprehensive analysis of the influence of applied crystallization additives on the service life of self-compacting concrete (SCC), specifically when exposed to the effects of chemically aggressive environments. Attention is focused not only on the influence of a crystallization additive on the characteristics of the capillary porous structure of SCC, but mainly on its effects in terms of the long-term service life of self-compacting concrete. The effects of individual types of aggressive environments are evaluated on the basis of a set of physico-mechanical and physico-chemical analyses.

The Evaluation of the Effect of Crystallization Additives on Long Term Durability of Cement Composites

2018 ◽  
Vol 276 ◽  
pp. 265-270
Author(s):  
Ámos Dufka ◽  
Tomáš Melichar
Keyword(s):  
Pore Structure ◽  
Cement Composites ◽  
Self Compacting Concrete ◽  
Aggressive Environment ◽  
Physico Chemical ◽  
Influence Of Crystallization ◽  
Long Life ◽  
Capillary Pore

The article deals with the influence of crystallization additives on the life of self-compacting concrete (so-called SCC concrete), which are exposed to chemically aggressive environments. The focus is not only on the effect of the crystallization additive on the characteristics of the capillary-pore structure of SCC concrete, but especially long life durability of self-compacting concrete (two years expozition). The effect of individual types of aggressive environment is assessed on the basis of a set of physico-mechanical and physico-chemical analyzes.

scholarly journals Designing organic solvent separation membranes: Polymers, porous structures, 2D materials, and their combinations

2021 ◽  
Author(s):  
Ameya Manoj Tandel ◽  
Wenji Guo ◽  
Kelly Bye ◽  
Liang Huang ◽  
Michele Galizia ◽  
...  
Keyword(s):  
Organic Solvent ◽  
High Selectivity ◽  
2D Materials ◽  
Porous Structures ◽  
Membrane Materials ◽  
Term Stability ◽  
Long Term Stability ◽  
Separation Membranes ◽  
Tremendous Progress

As interest for membrane-based organic solvent separation increases, membrane materials exhibiting high permeance, high selectivity, and long-term stability against solvents are sought. Membrane technology has experienced tremendous progress by integrating...

The global iron industry and the Anthropocene

2020 ◽  
pp. 205301962098233
Author(s):  
Kevin Mallinger ◽  
Martin Mergili
Keyword(s):  
Iron Ore ◽  
Magnetic Particles ◽  
Steel Corrosion ◽  
Global Changes ◽  
Iron Industry ◽  
Iron And Steel ◽  
Physical Chemical ◽  
Organic Particles ◽  
Rock Overburden

Iron ore is the most mined metal and the second most mined mineral in the world. The mining of iron ore and the processing of iron and steel increased sharply during the 20th century and peaked at the beginning of the 21st century. Associated processes along the iron ore cycle (mining, processing, recycling, weathering) such as the massive displacement of rock, the emission of waste and pollutants, or the weathering of products resulted in long-term environmental and stratigraphic changes. Key findings link the iron ore industry to 170 gigatons of rock overburden, a global share of CO2 with 7.6%, mercury with 7.4%, and a variety of other metals, pollutants, and residues. These global changes led to physical, chemical, biological, magnetic, and sequential markers, which are used for the justification of the Anthropocene. The potential markers vary significantly regarding their persistence and measurability, but key findings are summarised as TMPs (Technogenic Magnetic Particles), SCPs (Spheroidal Carbonaceous fly ash Particles), POPs (Persistent Organic Particles), heavy metals (vanadium, mercury, etc.), as well as steel input and steel corrosion residues.

scholarly journals Biological Control and Mitigation of Aflatoxin Contamination in Commodities

Toxins ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 104
Author(s):  
Ferenc Peles ◽  
Péter Sipos ◽  
Szilvia Kovács ◽  
Zoltán Győri ◽  
István Pócsi ◽  
...  
Keyword(s):  
Biological Control ◽  
Secondary Metabolites ◽  
Competitive Exclusion ◽  
Aflatoxin Contamination ◽  
Post Harvest ◽  
Physical Chemical ◽  
Synthetic Chemicals ◽  
Ruminal Degradation

Aflatoxins (AFs) are toxic secondary metabolites produced mostly by Aspergillus species. AF contamination entering the feed and food chain has been a crucial long-term issue for veterinarians, medicals, agroindustry experts, and researchers working in this field. Although different (physical, chemical, and biological) technologies have been developed, tested, and employed to mitigate the detrimental effects of mycotoxins, including AFs, universal methods are still not available to reduce AF levels in feed and food in the last decades. Possible biological control by bacteria, yeasts, and fungi, their excretes, the role of the ruminal degradation, pre-harvest biocontrol by competitive exclusion or biofungicides, and post-harvest technologies and practices based on biological agents currently used to alleviate the toxic effects of AFs are collected in this review. Pre-harvest biocontrol technologies can give us the greatest opportunity to reduce AF production on the spot. Together with post-harvest applications of bacteria or fungal cultures, these technologies can help us strictly reduce AF contamination without synthetic chemicals.

Physical-chemical and Microbiological Characteristics of Organic Strawberries Conserved with Biofilms and Refrigeration

2012 ◽  
Vol 1 (3) ◽  
pp. 247
Author(s):  
Raquel Pires Campos ◽  
Angela Kwiatkowski ◽  
Carolina Dario Tonhi ◽  
Edmar Clemente
Keyword(s):  
Mass Loss ◽  
Cassava Starch ◽  
Edible Coatings ◽  
Chemical Analyses ◽  
Organic System ◽  
Titrable Acidity ◽  
Physical Chemical ◽  
Microbiological Characteristics

Biodegrabable and edible coatings were applied on fresh strawberries (<em>Fragaria </em>x <em>ananassa Duch</em>), ‘Camarosa cultivar’, produced in organic system and stored at 10ºC for nine days. Color, mass loss, incidence of rottenness and chemical analyses contents was evaluated. Suspension of cassava starch and grains of kefir milk reduced evolution of fruit coloration when compared uncoated fruits. Treatment associated cassava starch and kefir liquid resulted in a lower rottenness incidence and less mass loss of the fruits, is therefore recommended for postharvest organic strawberries. Anthocyanin and titrable acidity contents increased during storage, regardless of the treatments in general.

scholarly journals The UV-Vis Study On Anthocyanin Pigments Activities Extracted From Gayo Arabika Coffee Husks

Elkawnie ◽  
2019 ◽  
Vol 5 (2) ◽  
pp. 147
Author(s):  
Hasby Hasby ◽  
Nurhafidhah Nurhafidhah ◽  
Said Ali Akbar
Keyword(s):  
Hydrochloric Acid ◽  
Acid Solution ◽  
Absorption Peak ◽  
Solution Temperature ◽  
Arabica Coffee ◽  
Coffee Husk ◽  
Long Term Stability ◽  
Acidic Conditions ◽  
Anthocyanin Pigments

The anthocyanin activity of Gayo Arabica coffee husk in variations in acid solution, temperature, and pH has been assessed through UV-Vis studies. It is important to optimize these factors to increase the long-term stability of anthocyanins for use in various fields. Gayo Arabica coffee husks was extracted through maceration method with methanol. This process obtained a coffee husks extract of 1.176 mg/μL. The UV-Vis spectrum of the extract displayed the major absorption peak at λmax= 529 nm in hydrochloric acid (HCl), this assigned by the electronic transition from flavylium as the particular characteristic of anthocyanin compounds. The anthocyanin from the extract was stable at temperatures of 35oC and 50oC, to have a major absorption peak at λmax= 529 nm. Therefore, it could probably be said that the lower the temperature, the higher the absorbance value of anthocyanin. Then, husks extract was getting red at pH 1 and 3; almost colorless at pH 5, 8 and 10; and yellow at pH 12. The more acidic conditions causes more anthocyanin pigments to be observed in the form of flavylium or oxonium cations color. Finally, Gayo Arabica coffee husks extract can absorb both ultraviolet (UV) and visible light (visible).

scholarly journals The Complex Compound of Amino Acids With Titanium (III) as a Method to Control and Synthesis of Different Structures of TiO2 Nanoparticles; Usage as Photocatalysts to Oxidize Alcohols to Aldehyde

2021 ◽  
Author(s):  
Yahya Absalan ◽  
Nazanin Noroozi Shad ◽  
Mostafa Gholizadeh
Keyword(s):  
Amino Acids ◽  
Titanium Dioxide ◽  
Uv Light ◽  
Chemical Analyses ◽  
Benzyl Alcohols ◽  
Titanium Dioxide Nanoparticle ◽  
Physical Chemical ◽  
Nitrobenzyl Alcohol ◽  
Different Types ◽  
Full Investigation

Abstract Different types of the amino acids (Glutamine, Glycine, Alanine) were used to coordinate TiCl3 in order to investigating the best precursor for synthesis of TiO2. Also, a full investigation was carried out to synthesis four different structures of TiO2 nanoparticles [TiO2 (A0.8R0.2), TiO2 (A0.6R0.4), TiO2 (Anatase), and TiO2 (Rutile)]. Oxidation of derivatives alcohol to their corresponding aldehyde through the obtained nanoparticles, as a photocatalyst, under UV light was considered to investigate the best structure of TiO2. Different physical-chemical analyses were applied to investigate the result. The result showed that the titanium dioxide nanoparticle, synthesized from glycine was obtained at the least temperature and was chosen as a precursor to synthesis of four different types of TiO2. All the synthesized TiO2 were applied for oxidation of benzyl alcohols into benzaldehyde, as a test, and TiO2 (A0.6R0.4) could give the best result (87% efficiency). Then it was used to oxidize benzyl alcohol, 4-cholorobenzyl alcohol, 4-nitrobenzyl alcohol and 4-methoxybenzyl alcohol to their corresponding aldehyde and efficiency were 74, 92, 87, and 65% respectively.

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