Base metals used in the built environment

If  we  take  a moment to consider  how  the strong presence of Steel metal is  felt everywhere in building construction, it  may  come as  surprise  to  find  that  base  metals  are  equally   widely used. Steel is often   overthrown by base metals as roofing and cladding materials. However rarely is it challenged and substituted as   structural support   material    in building construction.

But then, that was a side dish; I think it is about time we squared up to the main course – which as you might   already know is unmasking the base metals. Base metals are differentiated from    ferrous metals   because they do not contain iron .In other words, base metals are   nonferrous and are known to react with oxygen easily to form oxides. Also, they are less expensive compared to precious metal like Gold and Silver because we happen to have a handsome supply of these metals in the earth’s crust and are easier to    manufacture. Examples that come readily to mind are: Aluminium, Copper, Lead, Zinc, Nickel and Titanium.

Now let us  cast a brief look   at the profiles some these base metals.

Aluminium                                                                 

Aluminium (see image below)is a lightweight, reflective, non-toxic, silver colored metal and if you are like me, came face to face with it, for the very first time in the form of kitchen cooking utensils. However it is also widely used in building construction. Aluminium is a common metal in the earth’s crust and is mined as a bauxite ore which is an impure form of aluminium oxide.

 

Aluminium is  ductile with a density of 2700kg/m3 and as such it can be formed into many shapes or used to make wires. When alloyed with 1.25% manganese, it is used to make profiled roofing and cladding materials. These materials may be Zinc coated to make them more durable   and eye catching.

Aluminium roofing and cladding material are durable because of the protective cover of a natural aluminium l oxide film which  forms on its surface when it’s cut or scratched. This provide effective resistance to corrosion

Aluminium can be painted   to meet aesthetic needs, but must first be prepared in order to give paint a strong hold on the metal.

The metal is use for roofing, cladding, rainwater systems, vapor barrier, ceiling, windows, doorframes, structural framing, garage doors and many other uses.

Copper

Also called Dr. Copper (see image below)  because it is thought of as  possessing  a PhD in Economics. Well, how is that, you may ask. Simple- copper being a widely used metal in many sectors of the world economy, its market demand is said to have a high ability in revealing the underlying health of the world economy. In general   terms, the prices levels of cooper is said by analyst to be good indicator   of whether the world economy will do well or poorly. And this idea is strengthened by the facts that copper prices   are never affected by investor feeling   compared with precious metals whose prices are heavily influence by investor sentiments.

That said, copper is a red-brown metal best known for its use in making brass and bronze alloys. It can be worked at room temperature because at this temperature it is not brittle. Also copper is resistant to corrosion.

Copper is used to make alloys with Zinc, Tin, Aluminium, Nickel, or Silicon.

Brass-It’s an alloy of copper and Zinc (with Zinc at between 10% and 45%). It’s stronger and harder than copper but   more   corrosion resistant and   appealing than Zinc. Brass is used to make doors, windows and handrails.

Bronze-It’s an alloy of Copper and Tin (soft light silver colored metal).Bronze is used to make high quality doors and cladding materials. Bronze is harder, more durable and more resistant to corrosion than brass.

Copper is used among other things, as roofing cladding materials and is available as wire, rod, tube, foil, sheet and plates.

Lead

Lead (see image below) is a soft heavy grey lustrous metal and occur naturally as sulfide ore. It is a malleable material and can be formed into variety of shapes using a mallet. Lead sheets for roofing, cladding, flashing and gutter lining   are manufactured by   pressing thick sheets to the   desired specifications.

Lead is resistant to corrosion but it’s affected by organic acids. Also corrosion may occur when in contact with wet Portland cement or condensation under the sheets.

Lead  roofing  requires  a substrate   underlay  that is  continuous whose size  will  depend on  roof geometry  and   the lead  thickness. Its recommend that fixing should be made of copper or stainless steel. Also Lead may be joined using welding.

Lead is also used innovatively to manufacture Lead tiles that come in various sizes and shapes depending on customer specifications. The individual units may, for example, be made of plywood dressed with a lead sheet.

Lead  is harmful to  human being  and  many  countries  have banned  many   lead based products like Lead fuels, Paint with  lead  pigmentation ,lead  fishing  sinker and  lead pipes.

Zinc

Zinc (see image below) is a lustrous blue grey metal used to make brass alloy and galvanized iron sheets that are resistant rust and corrosion. It’s hard at room temperature   but become brittle at cold temperatures.

Standard products  are  pure Zinc and its  alloys(Zinc + Titanium + copper).Zinc  alloys  are  more stronger    with  reduced  thermal expansion  than pure  Zinc. Also the alloys   can be curved to produce interlocking cladding panels.

Zinc is applied to steel in a process called galvanization which works to protect ferrous metals against rusting

The metal is resistant to corrosion but should not be used in contact with copper. However it can be used with Aluminium and Lead. When in contact with Steel, Zinc should be in higher proportion to avoid corrosion. While  it’s  not affected  by Portland cement  ,its   reacts   to  acidic  hardwood timber  like  Oak, Chestnut  and  Western Cedar.

To fix Zinc sheets, it’s recommended to use galvanized or stainless steel. Watertight joints  may  be  done  by  soldering    using  Tin or  Lead solders  together with  Zinc chloride  flux.

Zinc  is used  for  making  roofing and  cladding  sheets   and addition to  other secondary use  like in  coated corrugated  iron sheets.

Titanium

Titanium is a strong, lightweight white metal .The  metal  is in abundant supply in the earth’s crust but paradoxically it is very expensive(see image below).

It is  resistant to both acidic and alkaline   corrosion  because of  the  protective  oxide film that form on it is surface and  has high  density  of  4510kg/m3  when  measured against  Aluminium -2700kg/m3  and  Steel  -7900kg/m3.Moreover  Titanium is  less  elastic  and with  low  thermal  expansion than Steel. Lastly it has high melting point at 1670C making it effectively   a non-combustible material.

Titanium roofing and cladding sheet are light, cutting down dead weight and   need for   expensive supporting structure.Titanium can welded but in oxygen freed space.

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