Volcanic tuff as a raw material for alkali-activated materials

Abstract

Currently, the use of geopolymers as cementitious materials is constantly evolving due to their excellent properties and efficiency, such as low CO2 emissions, high compressive strength, and low permeability. On the other hand, volcanic tuff can be used as a potential raw material for synthetic geopolymers due to its reactivity, wide availability in nature, low extraction cost, and relatively low environmental impact. This paper presents a review of recent studies on the use of volcanic tuff as a main binder in the manufacture of geopolymers. The results reported by the researchers concern durability and mechanical performance, as well as the factors affecting these properties, such as the effect of activator types, sodium hydroxide (NaOH) concentration, curing temperature, and the addition of other cementitious materials. The results clearly showed that increasing the activator concentration and curing temperature had a significant effect on mechanical properties, as well as that the activator (Na2SiO3 + NaOH) reduced water absorption values by creating a more compact structure in all samples than activation by NaOH alone. Recent results suggest that volcanic tuff-based geopolymers have mechanical, physical, and durability properties similar to or better than those of ordinary Portland cement concrete, but further research is needed to make them an economically and technically efficient building material.