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 (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.
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 (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 (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 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.