Materials dug out of the Earth are used for constructing buildings. Limestone, marble and granite are mined from quarries. Brick, concrete, cement, glass, iron and other metals also come from the ground, but they need to be processed before being used. Clay is used to make bricks; limestone and clay make cement; sand is manufactured to make glass and metals are extracted from their ores.
Limestone is chemically called calcium carbonate. It decomposes (breaks down) when heated. The word equation for the thermal decomposition of limestone is:
The reaction can be written in chemical symbols as well:
Cement is made by adding clay to heated limestone. Sand and gravel are mixed with cement and water to make concrete.
Cement can also be mixed with sand and water to make mortar, which is used to stick bricks together when building.
To make reinforced concrete, normal concrete is poured around steel rods. Concrete on its own is strong when squashed (compressed), but weaker when pulled. Steel rods or mesh in reinforced concrete increase its strength under tension (pulling).
Quarries are sources of a lot of materials, but also create environmental problems. The landscape is damaged and there is a lot of noise and dust pollution from machinery and explosives used, as well as lorries that transport the materials.