Week 8 - Concrete Research

• Concrete is commonly made of a mixture of powdered cement, water, sand and gravel.
• Reinforced concrete is a composite material in which the concrete’s relatively low tensile strength and ductility are counteracted by the inclusion of reinforcement having higher tensile strength and/or ductility.
• Reinforcement is usually steel bars that are embedded in the concrete.
• The chemical environment of the hardened concrete causes a film to form on the surface of the steel reinforcement, making it more resistant to corrosion.
• When the steel reinforcements do begin to rust, the rust expands and tends to flake, causing the concrete to crack and the bond between concrete and steel to break.
• Cracking can allow moisture into the concrete also causing the reinforcement to rust.
• Without maintenance, concrete will begin to decay and get damaged after 20 years, as can be seen from the Chernobyl disaster in Ukraine. Plant root systems will begin to get into the concrete and break up the structure.
• In fire, concrete peels away layer by layer. As water is pulled out of the concrete from the heat of the fire, thin layers of concrete with the aggregates visible, begin to fall off the wall.