Issue 38

U. Haider et alii, Frattura ed Integrità Strutturale, 38 (2016) 305-318; DOI: 10.3221/IGF-ESIS.38.41 316 0 1000 2000 3000 4000 5000 6000 7000 0 10 20 30 40 50 Charge (Coulombs) Age (hours) 60% Raw fly ash 60% Second layer 60% Third layer 0 2 4 6 8 10 12 0 10 20 30 40 50 Concentration of Cl- (mg) in 1 g of samples Depth (mm) 60% Raw fly ash 60% Second layer 60% Third layer (a) (b) Figure 8 : Charge passed vs age of specimens (a) , and chloride concentration vs depth of penetration (b) . C ONCLUSION n this research wet separation of brown coal raw fly ash from Počerady power plant of Czech Republic was carried out using water. Physical, morphological, chemical properties of separated parts were tested, and mechanical behaviour, durability in high volume cementitious mixtures were tested which leads to the following conclusions: 1. Three layers of raw fly ash were formed as it was added and mixed in water; particles of first layer which floated on the surface of water constituted of only about 1-5% of raw fly ash. 2. Second layer of particles were found to be finer particles as compared to raw fly ash. They consisted of mostly porous glassy spherical and rounded particles of submicron to ultrafine size rich in Si and Al while having very less contents of Fe in them. 3. The cementitious mixtures of second layer particles showed 7% increase in compressive strength as compared to raw fly ash cementitious mixtures and cementitious second layer specimens showed lesser chloride permeability and more resistance to ingress of chlorides. 4. Third layer particles were found to be coarse particles as compared to either second layer or raw fly ash particles. Morphologically third layer particles consisted of compact and large slaggy particles of several hundred microns size, rich in Si, Al, Fe, and heavy transition metals. 5. Cementitious mixtures of third layer particles showed 20% more flexural strength with large deformations as compared to cementitious mixtures of raw fly ash particles. Compressive strength was reduced and penetration of chlorides was found to be more as compared to raw fly ash. A CKNOWLEDGEMENT he authors would like to thank Buildings and Settlement Information Modelling, Technology and Infrastructure for Sustainable Development under the project TE 02000077 by TAČR for providing funding for this research. R EFERENCES [1] Blissett, R.S., Rowson, N.A., A review of the multi-component utilisation of coal fly ash, Fuel, 97 (2012) 1–23. DOI: 10.1016/j.fuel.2012.03.024. [2] Nicholls, T., How the Energy Industry Works: An Insiders' Guide, Silverstone Communications Ltd., London (2009) 111–112. [3] Cez Group, http://www.cez.cz/en/power-plants-and-environment/coal-fired-power-plants.html , (2015). I T