Bricks may seem dull and mundane, but they have a history and come in all shapes and sizes...read on.
The first known bricks have been dated to about 7,500 BC and were made from sun dried mud in the Upper Tigris area of south eastern Turkey. Archeological evidence shows the first fired bricks were probably produced in the third millennium BC in the middle east. Mud bricks don't stand up to tough weather conditions, so the development of fired bricks meant permanent buildings could be constructed in areas with high rainfall or cold or very hot weather. Bricks have the added advantage of being good insulators and storing heat during the day and releasing it slowly when the sun goes down.
By 1200 BC brick making was widespread - there is ample archeological evidence of their use across Europe and Asia and the Romans helped spread bricks across the Roman Empire.
Much later in the 18th and 19th centuries the development of transport networks and vehicles made the manufacture of building materials more centralised and industrialised. Up until then bricks, being heavy in bulk, tended to be made close to where they were used for construction. This industrialisation of the process made shape and size more standardised as well. This made construction quicker and simpler for bricklayers, rather than using stones of various shapes and sizes, requiring "jigsaw skills". Fast construction was vital during the industrial revolution, so the use of bricks became increasingly popular.
So what's in a brick? Bricks are most commonly made from clay. Raw clay is mixed with sand (to reduce shrinkage). The mixture is ground and mixed with water before being pressed into steel moulds, using a hydraulic press. The bricks are then fired to 1,000 centigrade, which locks in their strength. Modern brick-making involves rail kilns, where bricks are put through a kiln on a conveyor belt, slowly moving through to achieve continuous production.
Of course not all bricks are the same. For instance some a redder, others more yellow or pale. The colour is influenced by the mineral content of the clay used. So red bricks have a high iron content while pale bricks have a higher lime content. Also the hotter the temperature when firing the bricks, the darker they will be. Modern, concrete bricks tend to be grey.
So what do bricklayers like in a brick? First of all, bricklaying is a manual job so it's important that bricks can be picked up and handled easily in one hand, so that cement can be laid with a trowel with the other hand. This makes the job of bricklaying quicker. But there are other considerations, depending on the nature of the job. Brick colour, density, thermal qualities, fire resistance and size can all be relevant. Often large concrete blocks are used by bricklayers for internal, unseen work. As they are larger, not so many are required so with two bricklayers on the job a wall can go up quickly. Obviously with decorative or exposed brickwork the colour or even shape will be important to create the right effect.
Bricks began life as a step towards building stronger, more permanent buildings. But now bricklayers use them not only for buildings and walls but also for paving and pedestrian precincts - the modern equivalent of cobbles. Bricks are also used in industries requiring furnaces. The bricks used to build furnaces deal with regular, very high heats of 1,500 centigrade, for the production of glass and metals, so they need to be specially manufactured to be suitable for that sort of environment.
Bricks are everywhere but few people know their qualities, how they are made or where they originate from. They have been around for millennia, and so have the bricklayers who lay them. They are a strong, dependable building material that has changed very little for thousands of years and that will doubtless go on sheltering us for centuries to come.