Most precast concrete and masonry plants are within 200 miles of the project site. Concrete consists of approximately 7 to 15% cementitious materials (cement and SCMs), 25 to 30% fine aggregate (sand), 30 to 50% coarse aggregate (gravel or crushed stone), and 15 to 20% water. The cement is manufactured primarily from limestone, shells or chalk, and shale, clay, sand, or iron ore mined from a quarry near the plant. Natural gravel and sand are usually dug or dredged from a pit, river, lake, or seabed. Crushed aggregate is produced by crushing quarry rock, boulders, or large gravel. Water is generally from public water supplies or nearby rivers. Cement and aggregates are relatively inexpensive and heavy, and shipping them by truck is generally not economical.

 

Shipping by boat, barge, or rail uses approximately 70% less energy than shipping by truck. Approximately 15% of the cement used in the U.S. is imported from countries other than Canada.