Structure of the Earth
Lithosphere - Outer layer made up of he crust and top part of the mantle. Made up of tectonic plates, which are less dense than the mantle.
- The mantle is the area between the core and the crust. Just below the crust it is cold and rigid, but nearer the core it becomes hot and non-rigid.
- The Earth's core transfers energy, so the temperature of the mantle increases with depth.
- Convection currents slowly move the tectonic plates.
- Oceanic crust is denser than continental crust.
- Subduction - Oceanic an dcontinental plates collide and one of the plates is pulled down towards the hotter part of the mantle, and partially melts.
- Magma rises up through teh crust because it is less dense than the crust, this causes volcanoes.
- Slower volcanic eruptions produces runny lava, which has iron-rich basalt in it.
- Explosive eruptions produces thick lava, which has silica-rich ryolite in it.
Raw materials - Some raw materials are found in the Earth's crust, whcih are used to make construction materials.
Rock hardness -
Sedimentary rock - Made from compressed and cemented together soft sediments. (limestone)
Metamophic rock - Formed when limestone is changed by heat and pressure. Typically composed of interlocking carbonate crystals. (marble)
Igneous rock - Formed when magma cools and solidifies. Interlocking crystals, very hard. (granite)
Thermal decomposition - Reaction when one substance breaks down when heated to give at least two new substances.
Calcium carbonate thermally decomposes when heated: calcium carbonate makes calcium oxide + carbon dioxideCement is made when limestone is heated with clay. Concrete is made by mixing cement, sand and small stones with water.
Reinforced concrete - Composite material which has steel rods or mesh running through it to make it a better construction material. The composite can still distinguish at least two materials.
Reinforced concrete is used in buildings because it is more flexible and unlike concrete, will not crack under tension.