About: http://webisa.webdatacommons.org/365012393

Property	Value
http://www.w3.org/1999/02/22-rdf-syntax-ns#type	http://www.w3.org/ns/prov#Entity
http://www.w3.org/ns/prov#value	Pozzolanic materials, such as fly ash, montmorillonite clay, diatomaceous earth, and pumice, were considered optional ingredients, but could replace up to about 20% of the cement.
http://www.w3.org/ns/prov#wasQuotedFrom	google.com