Use of up-flow percolation test to assess the environmental properties of raw and treated fly ash

Vladana N. Rajakovic-Ognjanovic1, Milica Karanac2, Jasna Smolar3, Ana Petkovsek3, Maja Dolic4, Jovan Despotovic1

1 Institute of Hydrotechnics and Environmental Engineering, Faculty of Civil Engineering, University of Belgrade, Bulevar kralja Aleksandra 73, 11 000 Belgrade, Serbia
2 University of Belgrade, Innovation Center of the Faculty of Technology and Metallurgy ltd. In Belgrade, Karnegijeva 4, 11000 Belgrade, Serbia
3 University of Ljubljana, Faculty of Civil and Geodetic Engineering, Jamova 2, 1000 Ljubljana, Slovenia
4 University of Belgrade, Vinca Institute of Nuclear Sciences, P.O. Box 522, 11001 Belgrade, Serbia


Fly ash (FA) is a by-product created from the burning of coal in thermal power plants. FA mainly consists of mineral compounds that make them naturally caustic. Despite this, research has shown that FA may be utilized as an alternative material in civil engineering, hydrotechnics and agronomy. Leaching tests may provide theoretical validation that FA may be used as an alternative sorbent or additive in construction material. In this paper, the results of up-flow percolation tests performed on raw FA as well as lime and cement modified samples (MFA) are presented. This method was chosen as it yields the most reliable assessment of releasing heavy metals under long-term exploitation. The research has focused on the leaching behaviour of Sb, As and Se in raw, lime and cement MFA samples. Raw FA was found to leach Se, As and Sb metal ions, cement modification did not prevent Sb and Se leachates, while lime-modified MFA was found to be the most stable material.


fly ash; heavy metals; leaching; up-flow percolation

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