Microstructure Changes in Autoclaved Aerated Concrete during Carbonation under Working and Accelerated Conditions

Abstract

The microstructure of AAC changes during carbonation, resulting in degradation such as cracking. AAC panels under working conditions (Field-AAC) aged 5 to 33 years and AAC blocks carbonated under accelerated conditions (Labo-AAC) were subjected to microstructural analysis. The degree of carbonation increased with time and approached 60% both under working and accelerated conditions. Changes of micro-level structures such as surface and crystal structures were more significant under accelerated conditions than under working conditions. Meso-level structures such as the interparticle pore volume were similar regardless of the carbonation conditions. The increase in drying shrinkage was more significant under accelerated conditions than under working conditions because it originated not only from the moisture characteristics but also the micro-level structures.