Aluminium Extra
100 % RECYCLABLE ALUMINIUM ?
By Phil Slinger CAB Chief Executive
» A LOT HAS BEEN CLAIMED about the benefits of aluminium by CAB and many other associations , but we should also ask : “ Where would we be today without this material ?” With a high strength to weight ratio , aluminium is a structural engineering material , without it we would not have the modern airliners of today , or indeed much in the way of space flight . On the ground , more of our vehicles are now being made from aluminium , as less weight means less energy used in propulsion and potentially longer lasting vehicles . In fact , there are so many uses of the material across our modern life , it is difficult to imagine life without it .
So how does all this translate to aluminium products used in construction ? The most obvious is in fenestration , windows , doors , curtain wall and atria roofing . But aluminium is also extensively used today in external cladding of buildings including roofing solutions such as standing seam designs . Despite some recent disastrous building fires where aluminium has been used , aluminium remains completely non-flammable .
Why is it specified so widely ? Together with its unique engineering characteristics , aluminium can last the lifetime of a building , or more to the point today , last the lifetime of a building envelope as we look to repurpose and re-clad existing building structures . After the aluminium ‘ in-use ’ phase , it can easily be removed , recycled and replaced . Aluminium also needs no other supporting material to achieve impressive spans and comes in a wide range of alloy types to suit many applications . With the further advancement of architectural aluminium finishes , now in an unlimited range of powder coatings colours in several exposure classes and the incredibly resilient anodising finishes , we now measure the life expectancy of building envelopes using aluminium in decades , not years .
In fact , 75 % of all aluminium in use today , since the material was first commercially produced in the 1880 ’ s , is still in use today . The growing demand for the material means that there is not enough scrap available to meet the growing market sectors across construction , transport and packaging . Today we can only meet a third of the demand by recycling and , as a result , the monetary value of scrap aluminium remains high .
So is aluminium 100 % recyclable ? In practice , yes , and most importantly , many times over with no loss of structural integrity . The thermal breaks , stainless steel screws , gaskets and hardware can now be easily be removed from post consumer scrap in automated processes , leaving the aluminium in chipped form ready to melt back into billet production with no loss of quality . One of the key facts to aluminium recyclability is that it takes just 5 % energy to recycle aluminium compared to the energy needed to extract new aluminium from the earths crust .
Following oxygen and silicon , aluminium is the third most abundant element in the Earth ’ s crust . Often close to the Earth surface in the form of bauxite , from which alumina is extracted , is easy to source in open cast mines which can quickly be re-landscaped often with the fauna which was initially removed . Aluminium production also continues to become more efficient reducing its embodied carbon with prime ( newly mined ) ’ lowcarbon ’ billet equating to just 4.00 tCO2e ( shorthand for carbon dioxide equivalents ). In comparison , the average production of one ton of aluminium primary aluminium has an emission of 16.7 tCO2e . When added with 75 % post consumer scrap , as a typical example , the carbon dioxide equivalent is lowered still further to just 2.3 tCO2e . With continuing steps being made in the use of more renewable energy sources to produce aluminium such as hydro electricity and now with the promise of the use of hydrogen in the future , the embodiment of carbon in prime aluminium will continue to fall .
Today , the challenge in recycling aluminium is to keep the post consumer scrap separated into alloy grades , fortunately there are only a few grades used in construction and with the help of a spectrometer these can easily be identified prior to the disassembly of post consumer products . With these recycled material grades , virtually 100 % recycling is achievable with no prime aluminium needed to produce new billet .
So should we specify recycled aluminium only ? Well no , as there is not enough to
42 » AUG 2021 » CLEARVIEW-UK . COM