Concrete is a composite construction material that was used in Roman Empire construction and is now the most widely used production material in the world. Concrete can be made on-site with separate materials. More commonly it is mixed from a bag of premix to which you simply add water. The process of using the premix is found here http://www.wikihow.com/Use-Prepackaged-Concrete-Mix. A calculator
. for determining how many bags are needed to finish a project can be found at http://www.concretenetwork.com/concrete/howmuch/calculator.htm.
