What is AAC is normally the first question asked? AAC (autoclaved aerated concrete) is a common building material that is now used in the US. It’s a building material that can be cost effective with many benefits. Most builders, concrete contractors, and homeowners in the US are aware of the new building material AAC yet. There are two common types of AAC wall products - blocks and panels. Panels have reinforcement molded into them and can be as large as 20 feet long. Panels are typically secured to floors and decks in a mortar bed and held in position with the same kind of braces used by precast or tilt-up concrete contractors. Blocks, on the other hand, require less engineering and time to place, and reinforcement is easy to install onsite.