Concrete blocks have been used in the construction industry since the 1930s for a variety of purposes including cavity walls, internal partitions and load-bearing walls, although they did not commonly replace brick for the internal skin of cavity walls for another 30 years or so. A block is defined by BS 2028 as a walling unit that exceeds the length, width or height of a brick. In other words, a block is any walling unit that is bigger in at least one dimension than a brick measuring 215mm x 102.5mm x 65mm. That said, the height of a block must not exceed its length or six times its thickness. Typically the dimensions of blocks are 450mm long x 215mm high x 100mm wide (although different widths are available for different purposes).
The use of blocks has increased greatly since the late 1950s not only as a quick method of producing internal walls and partitions but also as a facing material in their own right. It is not uncommon to find neatly jointed, fair-faced blockwork as the finished wall surface inside a garage although the most common use is for the internal skins of cavity walls. Blocks have a number of advantages over bricks, the most obvious being that of productivity. By way of an example, laying one block with a ‘coordinating size’ (in other words, allowing for 10mm mortar joints) of 450mm x 225mm x 100mm is the equivalent of laying six bricks.
Blocks are generally divided into two types based on their material composition.
Fig. 36 Concrete blocks.