Bricks, cement and asbestos are the material which is used in road construction. Each material plays an important role in construction of road. A brick is a block or a single unit of a kneaded clay-bearing soil, sand and lime, or concrete material, fire hardened or air dried, used in masonry construction. Brick are produced in numerous types, materials, and sizes which vary with region and time period, and are produced in bulk quantities. Ordinary building bricks are made of a mixture of clay and sand (to which coal and other foreign substances are sometimes added), which is subjected to various processes,

Two most basic categories of brick are fired and non-fired brick. Calcium silicate bricks are also called sand lime or flint lime bricks depending on their ingredients. Rather than being made with clay they are made with lime binding the silicate material. Bricks are used for building, block paving and pavement. In the USA, brick pavement was found incapable of withstanding heavy traffic, citation needed] but it is coming back into use as a method of traffic calming or as a decorative surface in pedestrian precincts.

There are different types of bricks- Common Burnt Clay Bricks, Sand Lime Bricks (Calcium Silicate Bricks), Engineering Bricks, Concrete Bricks, fly ash clay bricks.

Cement also known as Mortar (mentioned in the saying bricks and mortar meaning walls and cement) is a binder, a substance that sets and hardens and can bind other materials together. Cements used in construction can be characterized as being either hydraulic or non-hydraulic. Non-hydraulic cement will not set in wet conditions or underwater, it sets as the cement dries and reacts with carbon dioxide in the air. Hydraulic cement is made by replacing some of the cement in a mix with activated aluminum silicates, pozzolanas, such as fly ash. Types of cements are Rapid Hardening Cement, Quick setting cement, Low Heat Cement, Sulphates resisting cement, Blast Furnace Slag Cement, Air Entraining Cement, Hydrographic cement etc.

Asbestos is a set of six naturally occurring silicate minerals which all have in common their eponymous asbesti form habit: long, thin fibrous crystals. It was used in such applications as electrical insulation for hotplate wiring and in building insulation. When asbestos is used for its resistance to fire or heat, the fibers are often mixed with cement or woven into fabric or mats.

Types of asbestos are Tremolite Asbestos, Actinolite Asbestos, Anthophyllite Asbestos, Chrysotile Asbestos, Amosite Asbestos, and Crocidolite Asbestos.

Portland cement gets its strength from chemical reactions between the cement and water. The process is known as hydration. This is a complex process that is best understood by first understanding the chemical composition of cement. Manufacture of cements- Lime or calcium oxide, CaO: from limestone, chalk, shells, shale or calcareous rock, Alumina, Al2O3: from bauxite, recycled aluminum, clay, Gypsum, CaSO4.2H20: found together with limestone etc.

Various tests to which cements must conform are laid down in national cement specifications to control the fineness, soundness, setting time, and strength of the cement. Tests are fineness, soundness, strength.

The world production of hydraulic cement was 3,300 million tonnes. The top three producers were China with 1,800, India with 220 and USA with 63.5 million tonnes for a combined total of over half the world total by the world's three most populated states, global consumption continued to climb, rising to 3585 Mt in 2011 and 3736 Mt in 2012, while annual growth rates eased to 8.3% and 4.2%, respectively.

FURTHER INFORMATION:

The Complete Technology Book on Bricks, Cement and Asbestos describes the detailed information on subject. The major contents of this book are- Molded and Ornamental Bricks and Blocks, Fire-bricks and Other Refractory Bricks , Hand-molding Processes,  Production of Cement Clinker, Grinding and Fineness of Cement, Monitoring and Identification of Airborne Asbestos (Synopsis), Getting, Cleaning, and Delivering the Clay, Plastic Molding by Machinery , The Stiff-plastic Process of Brickmaking etc.

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