scholarly journals CONCRETE WITH HIGH CONTENT OF FLY-ASH FOR COMMON USE IN CONDITIONS OF THE CZECH REPUBLIC

2014 ◽  
Vol 03 (25) ◽  
pp. 189-194
Author(s):  
Hana Šáchová .
2021 ◽  
Vol 13 (18) ◽  
pp. 10385
Author(s):  
Eliška Chmelová ◽  
Vojtech Kolar ◽  
Jiří Jan ◽  
Bruno M. Carreira ◽  
Andrea Landeira-Dabarca ◽  
...  

Deposits of coal combustion wastes, especially fly ash, are sources of environmental and health risks in industrial regions. Recently, fly ash deposits have been reported as habitat surrogates for some threatened arthropods in Central Europe. However, the potential environmental risks of fly ash have not yet been assessed in the region. We analysed concentrations of 19 minor and trace elements in 19 lignite combustion waste deposits in the Czech Republic. We assessed their environmental risks by comparison with the national and EU legislation limits, and with several commonly used indices. Over 50% of the samples exceeded the Czech national limits for As, Cu, V, or Zn, whilst only V exceeded the EU limits. For some studied elements, the high-risk indices were detected in several localities. Nevertheless, the measured water characteristics, the long-term presence of fly ash, previous leaching by acid rains, and the low amount of organic matter altogether can infer low biological availability of these elements. We presume the revealed high concentrations of some heavy metals at some studied sites can be harmful for some colonising species. Nevertheless, more ecotoxicological research on particular species is needed for final decision on their conservation potential for terrestrial and freshwater biota.


2016 ◽  
Vol 249 ◽  
pp. 21-27 ◽  
Author(s):  
Adam Hubáček ◽  
Rudolf Hela

The article deals with theme of high fly ash content concretes intended for long life constructions. Considering the still growing consumption of fly ash in construction concretes it is a live theme in the Czech Republic and abroad as well. The emphasis will be laid namely on characteristics and requirements for fresh concrete intended for construction of these specific concrete constructions. They are for instance waterproof constructions, tunnel linings, concretes for bridge and road constructions etc. Also the hardened concrete properties like compressive strength, resistance to pressure water, durability and further necessary parameters for obtainment of required properties of these concretes will be monitored.


2014 ◽  
Vol 969 ◽  
pp. 308-311
Author(s):  
Ondřej Zobal ◽  
Pavel Padevět ◽  
Vít Šmilauer ◽  
Zdeněk Bittnar

The use of fly ash as a substitute for cement clinker brings some benefits, but also problems. One of the biggest problems of using fly ash in general is its high variability. This paper is dedicated not only to the variability of fly ash in the Czech Republic, but the issue of different water absorption of fly ash is described here as well. In addition, one of the options for coping with variability is stated here. If we follow one of the main indicators for sorting fly ash, which is the grading curve, we can optimize the use of ash produced. Based on grading curves, the mixing of various ash fractions was optimized with regard to the porosity of the mixture. Porosity has a direct effect on the compressive strength of the resulting material. This optimization will subsequently be verified experimentally.


2015 ◽  
Vol 732 ◽  
pp. 407-410
Author(s):  
Ondřej Zobal ◽  
Pavel Padevět ◽  
Vít Šmilauer

The use of fly ash in cement and concrete has long been a common practice. However, in the Czech Republic, one of the largest producers of fly ash in the world, there is still a great mistrust of this material. One of the main reasons is variability properties of fly ash. But standard ČSN EN 450-2 defines the possibilities of optimizing the properties of fly ash. This paper is dedicated to optimizing the properties of fly ash, namely sorting and mixing.


2014 ◽  
Vol 887-888 ◽  
pp. 805-808 ◽  
Author(s):  
Vit Cerný ◽  
Šárka Keprdová

Artificial sintered aggregate produced by self-firing is one of the few building materials, which can be produced with only fly ash. If the character of the fly ash is optimal, no other additions are needed. However, not every fly ash has optimal composition. Quality of fly ash then influences composition of the mix, technological parameters and quality of produced aggregate. Parameters influence the process of self-firing, strength of granules during the phases of drying process, ignition and burning under given underpressure on an agglomerating bed. This often influences correct setting of proportion of combustion material and reduces quality of aggregate. The paper evaluates fly ash produced in the Czech Republic by both high temperature and fluidized bed combustions. Their granulometry, specific surface, bulk weight, structure, chemical composition and behavior at higher temperatures up to the melting point are evaluated.


1998 ◽  
Vol 12 (1) ◽  
pp. 7-24 ◽  
Author(s):  
Koupilova ◽  
Vagero ◽  
Leon ◽  
Pikhart ◽  
Prikazsky ◽  
...  

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