Introduction Modern cementitious concretes have been produced since the 18th century. Concrete is our most widely used man-made material at 1.5m3/person annually. As a result, the production of concrete accounts for more than 5% of all CO2 produced. Concrete’s widespread availability, ease of use, formability and low cost have ensured its enduring use for a great variety of structures. Its surface finish and texture may be varied widely by the use of appropriate formwork, mak