Analysis of reaction degree and factors of alkali-activated fly ash/slag

Abstract

The dissolution rates of alkali-activated fly ash (FA) and alkali-activated slag in hydrochloric acid (HCl) with various pH values were investigated. The geopolymerisation reaction degree of alkali-activated FA/slag (AAFS) can be determined based on the content of hydrochloric-acid-insoluble matter, so X-ray fluorescence, X-ray diffraction and Fourier-transformed infrared spectroscopy were used to analyse the hydrochloric-acid-insoluble matter of the alkali-activated FA and alkali-activated slag. Acid dissolution tests on the AAFS showed that the addition of slag increased the geopolymerisation degree of FA in most cases. For a certain slag content, the reaction degree of FA decreased with an increase in the modulus of the activator and increased with an increase in the liquid/solid ratio. An increase in activator concentration had a greater effect when the slag content was low. At low activator concentrations, the reaction degree of FA increased with an increase in slag content. The slag content corresponding to the highest reaction degree of the FA gradually reduced with an increase in activator concentration.