3.2. Concrete blocks
Light-weight/low-density concrete blocks are commonly used in the construction of envelope walls in multi-storey buildings.They are also used to a lesser extent to build load-bearing masonry walls. The basic composition of the blocks is cement, sand and coarse aggregates (less than 4 mm size). The energy content of the block will mainly depend on the cement percentage. Energy spent in crushing the coarse aggregate also contributes to the block energy calculation. The percentage of cement generally varies between 7 and 10% by weight. The quality of the block, particularly the compressive strength, is the deciding factor in the percentage of cement used. The energy content of a concrete block measuring 400 mm × 200 mm × 200 mm will be in the range of 12.3–15.0 MJ[47].