The term 'material in concrete' refers to CEMENT, which is a powdery substance made from a mixture of elements that hardens when mixed with water. CEMENT is the most important ingredient in concrete and is used to bind other materials together. It is also used in mortar and stucco, and as an adhesive for brick, stone, and tile. CEMENT is typically made from limestone, clay, sand, and iron ore, and is heated in a kiln to produce a fine powder.