An image analysis procedure to quantify the air void system of mortar and concrete

Abstract

The entrained air void system in cement paste and concrete directly affects both the fresh-state workability and the freeze-thaw durability of concrete pavements and structures. In order to effectively study the air void system, the volume, spacing, and size distribution of the air bubbles must be quantified. This manuscript describes an inexpensive and effective procedure to quantify the air void system using automatic image analysis. We compare various materials used for sample preparation and recommend a procedure to create more accurate images. We further implement a stereological analysis method in the form of a user-friendly and customizable Matlab script. The script was verified by comparing bulk density measurements between air-entrained and control samples with the air content computed by image analysis. As a result, the user can quantify the air void system in a variety of samples by computing the air content, specific surface, spacing, and size distribution of the bubbles.