Petrographic Characterization of Waste Rocks: Applicability as Concrete Aggregates

Abstract

Petrographic characterization showing mineralogical, textural and structural aspects of rocks is an essential technique in the study of the performance of concrete aggregates, specifically on the investigation of the alkali-aggregate reaction (AAR). The assessment of this deleterious reaction, considered as one of the most important pathologies, is a required test in the waste utilization programs. In this paper, waste rock samples of a feldspar mine were studied by optical microscopy, approaching aspects related to morphology, texture and alteration degree to determine the potential alkali reactivity for use as aggregates in cementitious mixtures. The rock studied shows characteristics that make it susceptible to be a reactive aggregate, due to, mainly, the strained quartz and the microcrystalline quartz. However, these results must be confirmed by standard mechanical test methods.