Concrete microstructural responses to the interaction of natural microfines and potassium acetate based deicer

This study investigates the chemical interactions and microstructural changes natural microfines induce in concrete laboratory specimens subjected to potassium acetate deicer. Microfines (material smaller than 75 μm) from 5 aggregate sources around the US were characterized and methodically added to concrete. Microscopy and petrographic testing were conducted with the goal of determining why the combination of the microfines and deicer causes deterioration of concrete. Microfines containing a high content of phyllosilicates showed the greatest impact on the concrete structure when exposed to potassium acetate deicers. In all cases, crystals of potassium sulfate were found in abundance throughout the system. ASR gel was not found to be the major form of deterioration although the degradation mechanism mimicked these effects.