Potential reactivity to alkalis of Portuguese volcanic aggregates for concrete

Abstract

In Portugal, volcanic rocks are commonly used as concrete aggregates for concrete in Madeira and Azores Islands and in a lesser extent in the Mainland. Nonetheless, the information about the potential alkali-silica reactivity of Portuguese volcanic rocks is rather scarce. In order to ful ll this lack of information and in the scope of a Portuguese research project, four volcanic aggregates from the Portuguese Mainland and Madeira Archipelago were investigated. For this purpose petrographic characterization (polarizing microscopy complemented by bulk chemical analysis and scanning electron microscopy with energy dispersive detector) along with expansion laboratory tests were carried out. In this paper, results of the investigation are presented aiming to establish a possible correlation among the results from the used methods.