Porous Systems Based on Alkali-Activated Fly Ash

Abstract

This paper studies possibilities of alkali-activated fly ash (AAFA) for the preparation of systems with preserved certain porosity level. Such systems would be used for example as filtration barriers, which are commonly prepared by both energetically and economically expensive sintering process at high temperatures. Porosity preservation was facilitated by the use of only coarse fraction from fly ash particles together with the use of low water to fly ash ratio and pressure compaction. Two different doses of sodium hydroxide were used to alkali activate fly ash. Prepared specimens were moist cured at 95 °C for 24 hours. Porosity and binder phase among the fly ash grains were investigated using scanning electron microscopy (SEM), mercury intrusion porosimetry (MIP) and capillary flow porosimetry (CFP). The results showed that it is possible to prepare AAFA-based porous systems and modify their properties by changing the activator dose.