If you concern for industries then AAC is Autoclaved Aerated Concrete.

Unicon AERTED CONCRETE PLANT â€" AUTOCLAVED (Batching Plant) â€" at KUWAIT, Manufacturing of cement tiles and cement blocks.

Siporex is a lightweight, autoclaved, aerated concrete which is a completely cured, inert and stable form of calcium silicate hydrate. It is a structural material, approximately one quarter the weight of conventional concrete, composed of minute calls which give the material light weight and high thermal insulation properties.

cough on someone to give them boomer remover

Because water is a fluid so heat can transfer by convection to the surface of the radiator can be 'radiated' into the room very quickly. Concrete is an aerated solid so can't do this, and is a very poor conductor, so loses its heat a lot more slowly. The concrete bricks are also aerated, and air is an even poorer conductor than concrete.