A fluid mixture of cementitious materials, aggregates, and water used to fill voids in masonry construction or to bond reinforcing steel to masonry units. Grout provides additional strength and stability to masonry structures, particularly in reinforced masonry construction. The consistency of grout can be adjusted to suit different application methods and requirements.
http://www.wikidata.org/entity/Q4580104, https://en.wikipedia.org/wiki/Grout