Dissolution of Volcanic Ash in Alkaline Environment for Cold Consolidation of Inorganic Binders.

A systematic study on the dissolution in concentrated alkali of two volcanic ashes from Cameroon, denoted as DAR and VN, is presented here. One volcanic ash, DAR, was 2 wt% richer in Fe and Ca and 4 wt% lower in Si than the other, designated as VN. Such natural raw materials are complex mixtures of aluminosilicate minerals (kaersutite, plagioclase, magnetite, diopside, thenardite, forsterite, hematite, and goethite) with a good proportion of amorphous phase (52 and 74 wt% for DAR and VN, respectively), which is more reactive than the crystalline phase in alkaline environments.

Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) as a potential on site tool to test geopolymerization reaction.

Geopolymers, synthesized starting from aluminosilicate precursors activated with alkaline solutions, constitute a class of materials of high interest as potential substitutes of traditional, cementitious, binders. Infrared spectroscopy is one of the routine analytical techniques employed to study these materials and to verify the occurrence of geopolymerization; on the other hand, its portable version working in diffuse reflection is not enough exploited for their characterization. The aim of this work is therefore to assess the potentiality of Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) in the study of geopolymers.