Abstract
This study aims at pursuing the changes in microstructural features and the characteristics of ASR gels composition in reactive aggregate-containing mortars immersed in NaCl solution, relating them to the expansion behavior of the mortars. The alkali contents of ASR gels produced in mortars in NaCl solution were found to be lower than in NaOH solution. Larger expansions in mortars in NaCl solution than in NaOH solution appear to result from the production of ASR gels with relatively low alkali contents in the mortars. A characteristic of microstructural features to be noted in the mortars produced by the use of cement with the higher C3A content was that ettringite started to be formed within many cracks caused by ASR at a time during the period of 14 to 56 days after immersion in NaCl solution. It is unclear whether the secondary ettringite formation influenced expansion of the mortars in NaCl solution
