Giant Cement Holding, a subsidiary of Spain's Cementos Portland Valderrivas, produces portland and masonry cement and related aggregates. The company operates limestone quarries and portland and masonry cement-manufacturing facilities through its Giant Cement, Keystone Cement and CDN-USA subsidiaries. Through subsidiaries Giant Resource Recovery, Omni, M&M Chemical, as well as Keystone Cement, Giant Cement processes aluminum cans and other waste into fuel for use in the production of cement and aggregates. Giant Cement Holding's operations stretch from Georgia to Maine. Headquartered in Summerville, S.C., Giant Cement Holdings employs nearly 800 people at its corporate location.