The ability to create that size coverage per weight and piece makes this a quick easy system to install. All boxes, outlets, and sleeves are cast into the panel for maximum ease and simplicity. Window and door frames are part of the system eliminating finish and trim carpentry. There are no weak links, all is balanced. The proportionate sizes give a look and feel of integrity no other system can offer.
Lightweight aggregate is the key.
Aggregate means the blend of sand and pebbles that are coated by the cement and water to make concrete. It will usually be of volcanic origin, enjoying the distant past free heat of the inner earth to create a molten state that when contacting air at the surface, the lava becomes aerated and less dense and therefore lighter. It can be called pumice or cinders and is available most anywhere. In addition, if sources are scarce, there are many new ways being created every day to make lightweight concrete. Strength is proportional to density so for high strength requirements like highways where truck tire pressures exert high stresses on concrete one would choose higher strength aggregates of regular concrete.