July 19 History of brick and its types
brick
Introduction :
Brick is an artificial (artificial) stone whose clay type is made from baking clay (molded clay) and its sand-lime type is made from making sand-lime clay (which is made by pressing a homogeneous mixture of silica sand and lime in a mold) with steam under pressure. A lot is obtained, concrete bricks are prepared in the same way as cement blocks. Clay brick is mainly made of aluminum silicates and sand-lime brick is composed of small silica aggregates that are stuck together by a calcium silicate paste.
This brick is usually gray in color, but it can be produced in other colors by adding suitable color. Bricks are produced in solid, perforated, hollow (blade and roof cavity) and thin pieces. Bricks are used in the construction of load-bearing walls, separating blades, block beam roofs, striking arches between beams, and exterior and interior facades of buildings.
History of brick
Brick is one of the oldest building materials, which according to some archaeologists, dates back to ten thousand years ago. In Iran, there are remains of pottery and brick kilns in Shush and Silk Kashan, which date back to the fourth millennium BC. It has been found. Also, signs of the production and consumption of bricks in India have been obtained, which indicates the six thousand year history of bricks in that country, the name of Babylonian bricks and the names of the clays on which charters, laws and the like were written, is believed to be the first time. From baking the soil of the walls and floor of the ovens, they have learned to bake bricks.
The primitive brick kilns undoubtedly consist of places where layers of firewood and clay are alternately stacked on top of each other.
The art of using bricks has gone from West Asia to the West of Egypt and then to Rome and to the East of India and China. In the 4th century, Europeans started using bricks, but after some time it fell out of favor and was popularized again from the 12th century. It started from Italy.
In ancient Iran, large and beautiful buildings were built, some of which are still standing. Such as the Kasri arch in the west of old Iran, the tomb of Shah Ismail Samani in the dome of Kavos and the mosque of Isfahan, which were built with bricks, as well as old bridges and dams, such as the daughter bridge of the Kabar dam in Qom, are among the old buildings.
Types of bricks in old Iran
In Iran, wherever stone is scarce and good soil is available, brick making and brick use have become common. The size of Elamite bricks is about 10x38x38 cm. The baking and use of bricks expanded during the Sassanid era and in large buildings like Fire temples have been used, the size of the bricks of this period was 44 x 44 x 7 to 8 and its dimensions were reduced to 20 x 20 x 3 to 4 cm.
In carpeting the floor of the building, a bigger brick called Khatai with dimensions of 5x25x25 cm or a bigger one called Nizami with dimensions of 40x4x5 cm is used. In the past, other types of bricks were Kazakh bricks. Before the First World War, the Russians produced it, whose dimensions were 5 x 10 x 20. Familiarity with brick and its raw materials. Brick soil is a mixture of clay, sand, feldspar, limestone, sulfates, sulfurs, phosphates, minerals of iron, manganese, magnesium, sodium, potassium, organic materials and…
2-1- Compliance with specifications and standards
In terms of physical, chemical and mechanical characteristics (such as dimensions, color and other characteristics), the bricks used in each project must be consistent with what is mentioned in the plans, agendas, private technical specifications and other contract documents. Samples of used bricks, both back and front, solid and perforated, hollow blade and roof, all types of clay and lime sand must be approved by the supervisory authority.
The physical, chemical and mechanical characteristics of bricks and their testing method should be according to the following Iranian standards:
– Standard No. 7: Clay bricks (including characteristics, sampling and testing methods)
– Standard No. 2909: Standard for features and test methods of ceiling beams and blocks
Standard No. 991: Refractory bricks for arched arches
– Any other Iranian standard that will be developed or revised until the conclusion of the agreement about bricks
As long as the Iranian standard is not formulated in some cases, the standards of the “International Organization for Standardization ISO” will be valid in the first place, and in the absence of the said standard, the German DIN, British BS, and American ASTM standards will be used as the criteria.
The stages of making bricks are:
Digging and extracting raw materials
Preparation of raw materials
molding
dry
Product unloading and storage
Types of brick kilns
After drying, the bricks are stacked in the kiln. The way they are stacked is in such a way that there is a gap between them so that hot gases and flames can pass through them. There are three types of brick kilns:
Oven, Hoffman and tunnel oven
It should be mentioned that tunnel kilns are the most modern brick kilns, in which premium and industrial ceramics are also baked. The characteristics of a good brick should make a ringing sound when it collides with another brick. It absorbs water. A good brick should be resistant to fire and should not be pasty or melt. The color of a good brick should be uniform and its surface should be uniform and without holes.
1-3- Features and minimum acceptable limits
1-3-1 Clay bricks
The bricks used in the facade must be free of appearance defects such as cracking, scaling, aluek and the like according to Iranian standard No. 7. The length, width and thickness of machine bricks should be 220±2, 105±1 and 55±1 mm, respectively. The length, width and thickness of manual bricks should be 210±4, 100±3 and 55±2 mm, respectively.
The thickness of thin-faced bricks in both machine and manual cases should be equal to 30±1 or 40±1 mm, and their length and width should be the same as thick bricks. The edges of the bricks should be straight and their corners should be vertical and their surfaces should be smooth, the complexity along the large surface of the brick is allowed up to 4 mm and along the medium surface of the brick up to 5 mm. The presence of a deep crack in the middle level up to a depth of 40 mm in the brick behind the work is normal.
The length of broken and jagged lines and angles in the brick behind the work should not exceed 15 mm, and the number of them in each brick should not be more than two. In perforated bricks, the holes should be perpendicular to the large surface of the brick and evenly distributed on its surface, and their total area should be between (25%) and (40%) of the surface of the brick.
The dimensions of the square holes and the diameter of the circular holes should be limited to 26 mm, and the thickness of the wall between the hole and the edge of the brick should be more than 15 mm, and the distance between the two holes should be more than 10 mm. The specific weight of both types of bricks should not be less than 1.7 and their spatial weight should not be less than 1.3 grams per cubic centimeter. The minimum compressive deflection of manual bricks is 80 kg/cm2, high resistance machine 175 kg/cm2, average machine 125 kg/cm2, and low resistance machine 85 kg/cm2.
The thickness of the hollow wall brick and roof clay block blades is at least 8 and their tolerance and dimensions are ±4 mm. Used bricks should be stable against frost and should not suffer visible damage such as flaking, cracking, and crushing in the frost test.
The weight percentage of 24-hour water absorption of machine bricks should not exceed 16 and in the case of manual bricks, it should not exceed 20, and in both types of bricks, it should not be less than 8. Hollow blade and ceiling bricks and thin brick pieces used in facade construction (approximately 20 x 40 x 200 or 20 x 30 x 200 mm or thin facade brick pieces with a thickness of about 20 mm with the pattern of several bricks) should at least have specifications Machine-made bricks with medium strength listed in Iranian Standard No. 7.
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