The versatility of concrete, the most widely used man-made material measured by tonnage, has been known for thousands of years writes Patrick Smith. Ancient Romans made wide use of concrete, the incredibly flexible and adaptive blend of water, aggregates, sand and cement, and today it is still being developed. For example, outside the more traditional uses, such as highways, bridges and buildings, global cement company Cemex is installing ecological concrete cookstoves to improve the quality of life of thou