Rocks and Building Materials: Calcium Carbonate.
Limestone is made up of Calcium Carbonate.
This can be thermally decomposed to form calcium oxide and carbon dioxide.
calcium carbonate calcium oxide + carbon dioxide
CaCO3 CaO + CO2
This is the same for Sodium Carbonate, Magnesium Carbonate and Copper Carbonate.
Calcium oxide reacts with water to produce calcium hydroxide.
calcium oxide + water → calcium hydroxide. CaO + H2O → Ca(OH)2.Calcium hydroxide is used to neutralise excess acidity, for example, in lakes and soils affected by acid rain.
Rocks and Building Materials: Limestone.
Limestone is quarried and is used for building, making concrete, making cement and making mortar and glass.
Carbonates react with acids to produce carbon dioxide, a salt and water.
calcium carbonate + hydrochloric acid → carbon dioxide + calcium chloride + water
CaCO3 + 2HCl → CO2 + CaCl2 + H2O
Calcium carbonate (Limestone) is damaged by acid rain. Sodium carbonate, magnesium carbonate, zinc carbonate and copper carbonate also react with acids: they fizz when in contact with acids, and the carbon dioxide released can be detected using limewater.
Cement = heat + powdered limestone + clay.
Mortar = cement + sand + water (used for joining bricks)
Concrete = cement + sand + water + agregate.
Rocks and Building Materials: Advantages and Disad
Limestone, cement and mortar gradually react with carbon dioxide dissolved in rainwater and wear away.
Limestone-made walls are damaged often because of this - gaps in between bricks in walls are caused by this also.
These gaps must be filled in or ‘pointed’.
Pollution from burning fossil fuels makes the rain more acidic than it should be, and this acid rain makes these problems worse.
Concrete is easily formed into different shapes before it sets hard.
It is strong when squashed, but weak when bent or stretched. However, concrete can be made much stronger by reinforcing it with steel.
Concrete building and bridges can look unattractive and some people dislike this.
Rocks and Building Materials: Quarrying
Must be able to evaluate effects of the quarrying of Limestone on the industry!
Limestone is a valuable natural resource. It can make glass and mortar so it is very useful.
The local economy of towns that surround a Limestone quarry can be boosted by the jobs provided from the quarry.
Quarrying is a heavy industry that creates noise and heavy traffic, which damages people's quality of life.
Limestone quarries are visible from long distances and may permanently disfigure the local environment.
Rocks and Building Materials: Lime Kiln
A lime kiln is used to make lots of calcium oxide.
It is filled with crushed limestone and heated with a hot air supply.
Calcium oxide comes out of the bottom of the kiln. Waste gases are left in the top.
Calcium oxide can produced in a rotary lime kiln.
A rotary lime kiln is a kiln that rotates the limestone in a heated drum.
This ensures that limestone is thoroughly mixed with hot air so that calcium carbonate is completely decomposed.