Studies of aggregate solubility for rapid assessment of their reaction capacity

The results of a study aimed at developing improved techniques for establishing the extent of aggregates participation in the alkali-silica reaction (ASR) are given. The solubility of the components of various aggregates in 1M KOH solution was determined, as well as the change of its pH, redox potential and specific electric conductivity in time, after the fillers in the form of fine powders were added to the KOH solution. After quartz flour had been added to the KOH solution, a change in the oxidation-reduction potential was observed, although the pH and specific electric conductivity remained stable. The effect of opaline sandstone and microsilica on the dependence of pH on the time differed significantly from that of other materials, the specific surface of which was much smaller. It is possible that the change of the pH of the solution in time depends on the specific surface of the added materials. Correlation between the solubility of silicon and the reaction capacity has not yet been experimentally established with a sufficient degree of certainty. To do this, further research is needed, varying the amount and type of tested materials. In addition, it is required to study the effect of other factors in more detail, such as the solubility of calcium contained in the aggregates and physical effects.

Author: L. Osterhus, C. Dombrowski, F. Schmidt-Doehl

Section: Concrete

Keywords: alkali-silica reaction, aggregate, solubility, testing