Complex sentence: The Romans mixed a particular type of volcanic ash called Pozzolane Rosse, from the Alban Hills volcano, with quicklime and water and used it to bind together decimenter-sized chunks of tuff, a aggregate of volcanic rock.
Split into simpler sentences: The Romans mixed a particular type of volcanic ash called Pozzolane Rosse, from the Alban Hills volcano, with quicklime and water. They used it to bind together decimenter-sized chunks of tuff, a aggregate of volcanic rock.