Natural volcanic pozzolans as an available raw material for alkali-activated materials in the foreseeable future: A review

Alkali-activated materials (MM) represent a line of research of great interest around the world as a real alternative to replace Portland cement (OPC). Despite this global interest, it is believed that current and future research should focus on overcoming the challenges that this technology faces with regard to its application at an industrial level. One of the main barriers to scale at the industrial level is the scarcity of studies on truly available and sustainable raw materials (precursors and activators). This review emphasizes natural volcanic pozzolans (NPs), also named volcanic ashes, as a globally available and sustainable raw material for industrial production of MM in the foreseeable future. To this end, the most important findings about mechanical performance and durability reported by researchers at a global level are presented and described, and a constructive analysis is carried out in order to establish the future challenges and opportunities to carry out a technological transition of these advances (industrial application) in countries rich in materials derived from volcanic activity. (C) 2018 Elsevier Ltd. All rights reserved.