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. 

Development of Structural Concrete with Fly Ash

2014 ◽  
Vol 1054 ◽  
pp. 143-147 ◽  
Author(s):  
Rudolf Hela ◽  
Martin Ťažký
Keyword(s):  
High Temperature ◽  
Fly Ash ◽  
Power Plants ◽  
Elasticity Modulus ◽  
Partial Replacement ◽  
Past Century ◽  
The Past ◽  
Temperature Combustion ◽  
Pozzolanic Properties ◽  
High Temperature Combustion

The paper describes problems of using fly ash in concrete. Using fly ash produced during high temperature combustion in power plants as addition for concrete has been known since the 60s of the past century. The Standard EN 206 Concrete - Specification, performance, production and conformity characterizes high temperature combustion fly ash as an addition of the type II, i.e. active addition with pozzolanic properties. Use of fly ash as an active addition also enables partial replacement of cement. The paper solves the extent of cement which can be replaced with fly ash in this manner. Influence of addition of fly ash on consistency of concrete, development of compressive strength and elasticity modulus at the age of 7, 28, 60 and 90 days of concrete are observed.

scholarly journals Simultaneous Determination of Dissolved Organic Carbon and Total Dissolved Nitrogen on a Coupled High-Temperature Combustion Total Organic Carbon-Nitrogen Chemiluminescence Detection (HTC TOC-NCD) System

2005 ◽  
Vol 2005 (4) ◽  
pp. 240-246 ◽  
Author(s):  
Xi Pan ◽  
Richard Sanders ◽  
Alan D. Tappin ◽  
Paul J. Worsfold ◽  
Eric P. Achterberg
Keyword(s):  
High Temperature ◽  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Data Acquisition ◽  
Simultaneous Determination ◽  
Dissolved Nitrogen ◽  
Total Dissolved Nitrogen ◽  
Temperature Combustion ◽  
High Temperature Combustion

The marine biogeochemistries of carbon and nitrogen have come under increased scrutiny because of their close involvement in climate change and coastal eutrophication. Recent studies have shown that the high-temperature combustion (HTC) technique is suitable for routine analyses of dissolved organic matter due to its good oxidation efficiency, high sensitivity, and precision. In our laboratory, a coupled HTC TOC-NCD system with a sample changer was used for the automated and simultaneous determination of dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) in seawater samples. TOC control software was used for TOC instrument control, DOC data acquisition, and data analysis. TDN data acquisition and manipulation was undertaken under LabVIEW. The combined system allowed simultaneous determination of DOC and TDN in the same sample using a single injection and provided low detection limits and excellent linear ranges for both DOC and TDN. The risk of contamination has been remarkably reduced due to the minimal sample manipulation and automated analyses. The optimised system provided a reliable tool for the routine determination of DOC and TDN in marine waters.

Use of Fluidized Bed Combustion Fly Ash as Addition Reducing Shrinkage of Concrete

2016 ◽  
Vol 865 ◽  
pp. 141-144 ◽  
Author(s):  
Lucia Osuská ◽  
Rudolf Hela
Keyword(s):  
Composite Material ◽  
High Temperature ◽  
Fly Ash ◽  
Fluidized Bed ◽  
Fresh Concrete ◽  
Fluidized Bed Combustion ◽  
Free Lime ◽  
Natural Properties ◽  
Temperature Combustion ◽  
High Temperature Combustion

Volumetric changes during ageing belong to natural properties of concrete. These changes, either growing or shrinking, can present a problem, which has to be taken into account during design and realization phases. This phenomenon is influenced by various factors and volumetric changes can be eliminated in many ways. One of the possibilities is setting appropriate combination of input materials and use of special additions and admixtures. This paper focused on verification of the method reducing shrinkage of concrete by means of using high temperature combustion fly ash combined with fluidized bed combustion fly ash as addition. The precondition is growth of new forms, in particular primary ettringite and monosulphate, which form because of the content free lime and sulphates in fluidized fly ash. If these minerals are formed in fresh concrete, they can positive prevent shrinkage without destruction of the composite material.

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