XANES, EXAFS and RMN Contributions to Follow the Structural Evolution Induced by AlkaliSilica Reaction in SiO2 Aggregate

In this work, we analyze and correlate information obtained from XANES, EXAFS and NMR on a SiO2 aggregate attacked by Alkali Silica Reaction (ASR). EXAFS and XANES results enable local order evaluation during the amorphization process within the aggregate. NMR results show the presence of amorphous and crystalline phases of silica during ASR attack. Besides, theoretical simulations of XANES spectra were performed and the atomic structure that generates the peak located 8 eV above the white-line (feature C in the text) was identified. The results lead us to deduce a change in the local order around silicon.