"Concrete is an artificial conglomerate or pudding stone, in which the pebbles which make up the greater part of the bulk are cemented together by lime mortar"
E. Dobson, A Rudimentary Treatise on Foundations and Concrete Works
Concrete is a manufactured stone and is made with water, aggregate, and cement in different proportions and often with chemical admixtures. Concrete is usually a mixture of 10–15 per cent cement; 15–20 per cent water; about 60–75 per cent aggregates, such as gravel, sand and limestone filler; about 5 per cent entrained air (trapped air bubbles); and less than 0.1 per cent chemical admixtures. Aggregates are often quarried stone or gravel—but may be natural (like stone and gravel), recycled (like crushed brick ...