Accelerated alkali silica reaction (ASR) tests usually incorporate the addition of alkalis to the mixing water or the immersion of test specimens in alkaline solutions. These measures are taken to increase the reaction potential and to compensate for alkali leaching. Mainly NaOH and in a few cases KOH are used for this ASR-enhancing purpose. Lithium on the other hand does not enhance ASR but can be used to supress ASR, if added in sufficient amounts. The effect of rubidium and caesium on expansion is not known. In this study the five mentioned alkalis are added to concrete tested with the concrete prism test to investigate their influence on expansion. The composition of the ASR products formed is determined with scanning electron microscopy and energy-dispersive X-ray spectroscopy. Additionally, the effect of the different alkalis on dissolution kinetics is studied.
The effect of the different alkalis on concrete expansion differs. However, these differences cannot be explained purely based on dissolution kinetics.