Lead immobilization by geopolymers based on mechanically activated fly ash

In this paper, the effectiveness of geopolymers based on initial and mechanically activated fly ash in immobilization of lead was investigated. Fly ash (FA) was firstly mechanically and then alkali activated at room temperature. The immobilization process was assessed by the means of the mechanical and leaching properties of geopolymers. The results indicated that the geopolymers based on mechanically activated FA were more effective in the immobilization of lead compared to the geopolymers based on the initial FA. Mechanical activation of FA led to a significant increase in strength and reduced Pb leaching from geopolymers. Higher effectiveness of Pb immobilization was the result of reduced porosity, i.e. higher compactness of geopolymers based on mechanically activated FA.