Masonry - Concrete block and brick manufacture
The vast majority of concrete blocks are produced by one of two different manufacturing processes. Aggregate blocks are produced by vibrating and compacting a mixture of cement, aggregate (coarse and fine) and water (plus admixtures, additives and pigments where necessary) into individual steel moulds of a specific size and shape. The formed block is immediately demoulded and cured to gain sufficient strength for handling. Secondary processes can be applied prior to packaging in order to enhance a particular property, e.g. insulation added to improve thermal properties.
Concrete bricks are generally formed in the same manner as concrete blocks but without vibration. They tend to use smaller aggregate and pigments for facing bricks to provide the necessary appearance for external applications.
For further information see the Concrete Block Association