Effects of Wet Separated and High Speed Milling Fly Ash Added in High Volume to Cementitious Materials

  • Usman Haider
    Affiliation

    Department of Mechanics, Faculty of Civil Engineering, Czech Technical University in Prague, Thákurova 7, Prague 6, 166 29, Czech Republic

  • Asif Ali
    Affiliation

    Department of Chemical Engineering, University of Engineering and Technology, Lahore, G.T Road, Lahore, Punjab 54890, Pakistan

  • Zdeněk Bittnar
    Affiliation

    Department of Mechanics, Faculty of Civil Engineering, Czech Technical University in Prague, Thákurova 7, Prague 6, 166 29, Czech Republic

  • Muhammad Humayon
    Affiliation

    Parsons Transportation Group, Peachtree Corners, 3577 Parkway lane, GA 30092, USA

  • Jan Valentin
    Affiliation

    Department of Material Engineering and Chemistry, Faculty of Civil Engineering, Czech Technical University in Prague, Thákurova 7, Prague 6, 166 29, Czech Republic

Abstract

In this research high speed milling was carried out on particles of brown coal raw fly ash, on second layer, and on third layer particles obtained from wet separation of brown coal raw fly ash. Due to milling process, median particle size d50 of raw fly ash, second layer, and third layer reduced by 46 %, 23 %, and 77 %, densities reduced by 11 %, 17 %, and 8 % respectively. Due to milling process, formation of agglomerations was observed, the standard deviation of the chemical composition of each element from the mean value reduced. After milling, high volume cementitious paste mixes were prepared with 60 % cement replacement. Due to the milling process the increase in compressive strength at 28 and 90 days was observed for raw fly ash is 59 % and 16 %, for second layer is 12 % and 15 %, for third layer and milled third layer is 78 % and 75 %. Flexural strength testing showed that due to the milling process the deflections at maximum loads have reduced considerably leading to brittle behavior of milled cementitious specimens. The testing for Mercury Intrusion Porosimetry showed that the cementitious specimens of third layer have maximum concentration of large capillary pores between 0.05 and 10 µm, whereas, all others have maximum concentration of medium capillary pores between 0.01 and 0.05 µm. Autogenous shrinkage of cementitious specimens was measured for first sixteen hours after mixing which showed that the second layer particles have the least shrinkage as compared to all other specimens.

Keywords: milling, raw fly ash, milled, second layer, third layer, cementitious, alumina, silicate, particles
Published online
2020-01-10
How to Cite
Haider, U., Ali, A., Bittnar, Z., Humayon, M., Valentin, J. “Effects of Wet Separated and High Speed Milling Fly Ash Added in High Volume to Cementitious Materials”, Periodica Polytechnica Civil Engineering, 64(1), pp. 81-100, 2020. https://doi.org/10.3311/PPci.14846
Section
Research Article