Synthetic aggregates are recycled materials recombined into a lightweight mineral aggregate substitute. No discussion of synthetics is complete without a quick background on the scope of the underlying natural/mineral aggregate market. Mineral aggregates are composed of sand, gravel or crushed stone, which is quarried from glaciated areas, riverbeds and alluvial fans. Nearly 3 billion tons of new construction aggregates annually come from more than 9,000 U.S. pits and quarries, and only 5 percent of that figure is recycled concrete. About 70 percent of all construction aggregates used in infrastructure are for roadbase. The demand for construction aggregates accounts for 73 percent of all mineral demand, with an annual rise of 1 percent since 1958. Aggregate extraction is complicated by environmental and legal issues, availability, urban expansion, costs, rock geology and distance from quarry to end-use site.
展开▼
