This article discusses what qualities make good bricks, and provides examples of each. First-class bricks are made from high-quality clay, have a smooth surface, and are expensive. Second-class bricks are bricks that are moderately well-burnt but have an irregular shape, rough surface, and might have hair-thin cracks. Third-class bricks are rough and the brick structure has unfair edges. Fourth-class bricks are very poor quality bricks and do not exist as bricks in the structure. The brick suppliers prefer to deal in first and second-class bricks. First and second-class bricks can be moulded by a ground-moulding process while third-class bricks are moulded by an oven process. Fourth-class bricks do not exist as building materials. – Good quality bricks are of moderate quality and are first-class bricks. These bricks must be moulded and have good properties as they will be used in house construction. Bricks of other classes also have properties that are first class, but they are not suitable for house construction. The ground moulding process is used to shape the rough surface of good quality bricks, which makes them an essential unit for building houses. Good quality bricks must not have hair-thin cracks or irregular shapes.
Very poor quality bricks have unfair edges and do not possess the required hardness. First-class bricks are those which are used in important structures and possess uniform size, shape, length, colour and hardness. Second-class bricks are used for less important constructions and possess hardness but not necessarily uniformity in size, shape or colour. Third-class bricks have a great deal of variation in size, shape, colour and hardness. Fourth-class bricks may not even possess hardness and so are only used for unimportant constructions.
First-class bricks, on the other hand, are made out of high-quality clay and fired clay that has been heated to a certain temperature. These bricks possess superior heat and sound insulating properties and durability strength. They also have a higher resistance to alkalis, acids, and organic solvents than other ceramic materials. Moreover, their surface is increased in durability due to their orange colour which is produced by prolonged firing. The standard shape of these bricks gives them greater strength and reliability for construction purposes.
The brick manufacturers Australia suggest that good bricks possess good building brick, possess requisite compressive strength and have plain and rectangular surfaces. They have a uniformly distributed red colour, uniform size and rectangular faces with straight edges. These bricks are usually made according to standards and weigh between 3-3.5 kg per case of 500. The sides of the bricks should measure 215 mm x 102 mm x 65 mm and the surface area should be around 19 cm2.
To ensure a good brick, a brick test is performed to determine if it can withstand particular loads without failure and extreme weather conditions. The compressive strength of the bricks should also be tested to determine their quality and sustainability. The bricks should also be tested for water absorption by performing a water absorption test and measuring the amount of moisture that is absorbed to find out how well they can withstand extreme conditions.
A good brick should not absorb more than 20 per cent of its dry weight when immersed in cold water for 24 hours. The bricks should also have a crushing strength of 5.50 n/mm2 or more, and their shade should be whichever is accepted in the local market. The bricks should also not exceed the specified maximum water absorption, which is usually 7 per cent for ordinary building bricks. To test for this, one needs to immerse a show brick in cold water for 24 hours and then weigh it to check if it has absorbed more than 7 per cent of its weight.
Good quality bricks should be well burnt, filled with mortar and have a proper frog. The bricks should be properly moulded to give them a uniform colour and some may even have a different colour on the face or body. The copper oxide may also be used to make the brick resemble a different colour. In addition, there should be a depression in the brick known as ‘frog’ which helps in better bonding with cement or mortar while laying. This makes sure that the walls are strong and can withstand extreme weather conditions.
Sun-dried clay bricks are usually used in masonry construction, as they require plastering to provide a waterproof layer. Burnt clay bricks are also used and have higher strength and insulation properties than sun-dried bricks. Ash bricks can be used for external walls as they have better insulating ability and better resistance to fire. Mortar is usually added to the joints of these bricks, to make them more resistant to water absorption. The uniform size of the brick increases the compressive strength of the wall. Clay bricks are also known for their high fire insulation and insulating ability, which makes them a good choice for building structures where heat resistance is required. To improve the joints, mortar and plaster can be used, which will increase the insulation properties of the wall.
Bricks are the ideal building material for any structure because of their high compressive strength and low porosity, making them an ideal choice for structural engineers. The strength and density of bricks depend on the material used to make them. Engineering bricks, concrete bricks, sand lime bricks and clay bricks are commonly used in construction. Engineering bricks are made from a mix of clay and sand that is fired in a kiln at very high temperatures. They have greater strength than regular clay bricks and are used to build load-bearing walls in storied buildings. Sand lime brick is made by mixing sand with lime and possibly a colour pigment, then firing it in a kiln to form a hard brick that can be used to form damp-proof courses or as facing brick. Concrete blocks are made from cement mixed with aggregates such as gravel or crushed stone, then cured under pressure or steam so that they become very strong.