Evaluation of crystalline rock mining waste for use as a concrete aggregate according to its petrography, physical indexes and mechanical strength

ABSTRACT

Currently, mining waste has been take an important role as a raw material in environmental sustainability programs, with the objective of minimizing the impacts resulting from mining activity. Given this, this research proposes to analyze pegmatite mining waste for use in aggregate for concrete. The samples were petrographically characterized according to their reactive potential to the Alkali-Aggregate Reaction under standard ABNT 15577-3 and tests were performed to evaluating the physical indexes and mechanical strength. It was found among the dimensions of pegmatites that two of them shows innocuous for alkali-aggregate reaction, because it contains levels of deleterious phases for RAA below the limit acceptable by the norm. Though, the other samples showed potential reactivity to RAA, because either contains deformed quartz, or both deleterious phases identified according to the standard used: deformed quartz and microgranular. The mechanical resistance assumed values below the average values presented by the consulted literature. This fact is justified by the degree of alteration observed in the studied samples. Mining residues were found to have been subjected to weathering, resulting in a drop in expected mechanical strength values. Considering the physical indexes, the samples showed good results regarding the moisture absorption capacity.

Keywords
Mining waste; concrete aggregate; petrography; physical indexes; mechanical resistance