Comparative Studies About the Physical Properties of Various Types of Bricks
TECHNICAL INFORMATION SHEET 16
HOW CLAY BRICKS ARE MADE
INTRODUCTION
Clay bricks are used in a wide range of buildings from housing to factories, and in the construction of tunnels, waterways, bridges etc. Their properties vary according to the purpose for which they are intended, but clays have provided the basic material of construction for centuries. Brick is the oldest manufactured building material, and much of its history is lost in antiquity. The oldest burnt or fired bricks have been found on the sites of the ancient cities of Babylonia, some of which are estimated to be about 6000 years old. Brick is, after all, virtually indestructible. The industry developed on traditional lines, using hand-making processes for the most part. The first patent for a clay-working machine was granted in the year 1619. Mechanisation, however, did not begin to take the place of manual methods until the middle of the nineteenth century. The moulded products were fired in relatively inefficient intermittent or static kilns until about 1858, when Hoffmann introduced a continuous kiln, which enabled all processes connected with the firing to be carried out concurrently and continuously. Since the introduction of clay working machinery and the Hoffmann Kiln, the Industry has made great progress, particularly since 1930, the output of bricks in Great Britain was doubled between 1930 and 1938.
RAW MATERIALS What is clay?
In brick-making terms, clay covers a range of naturally occurring raw materials which are used to make a product. The clays vary considerably in physical properties, colour, hardness etc, and mineralogical content. They do, however, have certain properties in common. They have the ability to be crushed and mixed with water to form a plastic material which can be moulded into various shapes. This can then be fired to a high temperature during which process it attains a hard, weather resistant characteristic. The key, in geological terms, is the mineral content of
HOW CLAY BRICKS ARE MADE
INTRODUCTION
Clay bricks are used in a wide range of buildings from housing to factories, and in the construction of tunnels, waterways, bridges etc. Their properties vary according to the purpose for which they are intended, but clays have provided the basic material of construction for centuries. Brick is the oldest manufactured building material, and much of its history is lost in antiquity. The oldest burnt or fired bricks have been found on the sites of the ancient cities of Babylonia, some of which are estimated to be about 6000 years old. Brick is, after all, virtually indestructible. The industry developed on traditional lines, using hand-making processes for the most part. The first patent for a clay-working machine was granted in the year 1619. Mechanisation, however, did not begin to take the place of manual methods until the middle of the nineteenth century. The moulded products were fired in relatively inefficient intermittent or static kilns until about 1858, when Hoffmann introduced a continuous kiln, which enabled all processes connected with the firing to be carried out concurrently and continuously. Since the introduction of clay working machinery and the Hoffmann Kiln, the Industry has made great progress, particularly since 1930, the output of bricks in Great Britain was doubled between 1930 and 1938.
RAW MATERIALS What is clay?
In brick-making terms, clay covers a range of naturally occurring raw materials which are used to make a product. The clays vary considerably in physical properties, colour, hardness etc, and mineralogical content. They do, however, have certain properties in common. They have the ability to be crushed and mixed with water to form a plastic material which can be moulded into various shapes. This can then be fired to a high temperature during which process it attains a hard, weather resistant characteristic. The key, in geological terms, is the mineral content of