Complex sentence: Lower density blocks may be produced by using cinders as an aggregate, and are known as cinder blocks (US), breeze blocks (UK) or clinker blocks (if bottom ash or clinker is used as an aggregate).
Split into simpler sentences: Lower density blocks may be produced by using cinders as an aggregate. The resulting blocks are known as cinder blocks (US), breeze blocks (UK) or clinker block (if bottom ash or clinker is used as an aggregate).