Alkali-silica reaction (ASR) - Investigation of crystallographic parameters of natural sands by backscattered electron diffraction

Reação álcali-sílica (RAS) - Investigação de parâmetros cristalográficos de areias naturais, por difração de elétrons retroespalhados

abstract:

This study involved analyzing several natural sands to ascertain the possible causes for distress due to ASR. The analyses were performed using the following techniques: X-ray diffractometry, accelerated mortar bar tests (AMBT), electron backscattering diffraction and elementary chemistry analyses, by FEG-SEM/EBSD/EDS. These experiments allowed identifying the presence of several mineral composites (such as microcline, anorthite, among others), as well as the microstructural-crystallographic planes of quartz (such as the Dauphiné type). From the results it could be inferred that the multiple techniques used, especially the FEG-SEM / EBSD, proved to be promising in the analysis of the ASR potential of sands for use in Portland cement mortars and concretes.

Keywords:
ASR; EBSD; natural sand; microstructural-crystallographic quartz planes; potential reactivity