Week 02_ EXP 2

Choose three materials, i.e. concrete, glass, marble, and do some research on their properties, i.e. the process of making each material, how long they will last, what makes them corrode, structural pros and cons, what these materials are typically used for, environmental impacts... Post a paragaph of your findings to your blog.

1. Glass

• The main raw material used to make glass is sand. To make clear glass, a special sand called silica sand is used. 
• This fine white sand is needed because it is very pure and does not contain other unwanted chemicals. 
• Glass production also needs limestone, soda ash and other chemicals to colour the glass. The production of glass uses energy, both during the extraction of the sand as well as during transportation and processing. Large amounts of fossil fuels (coal, oil and gas) are used during these stages, which in turn produce the greenhouse gas, carbon dioxide.
• Glass doesnt decompose. It does take a long time to become a solid, but glass now will be glass in millions of years. Some types of glass can be made to decompose by adding chemicals similar to what etching does to glass. The term devitrication refers to the decompositition of glass but this is under forced chemical changes and not something that's going to happen in a natural state. Glass takes thousands of years to become a solid. Glass darkens as it ages as well. Lava glass or obsidian is glass found in nature and can be dated back to the beginning of the Earth, and is still glass. 

2. Concrete

• Concrete is a composite construction material. It is composed of cement and other cementitious materials such as fly ash and slag cement, limestone, water and chemical admixtures. 
• Concrete degradation may have various causes. Concrete can be damaged by fire, aggregate expansion, sea water effects, bacterial corrosion, calcium leaching, physical damage and chemical damage (from carbonatation, chlorides, sulfates and distilled water). This process adversely affects concrete exposed to these damaging stimuli.

3. Metal

• A solid material that is typically hard, shiny, malleable, fusible, and ductile, with good electrical and thermal conductivity.
• Metal does not decompose. Rather, it rusts. It depends on the metal in question and the alloying elements that are in it as to how long it takes metal to rust.