Asphalt, Rock, Concrete, Timber and Steel

Not what it is cracked up to be

Civilizations have been using asphalt, rock, concrete, timber and steel for millennia. Yes even asphalt, although not as a ground treatment until the 1830′s.  They’re suitably durable and long lasting making them key components of the landscapes we construct for ourselves everywhere.  But did you know they are partly to blame for the impact we have on the environment?  They are so fundamental to our lives it is hard to imagine how they could inflict damage on the natural world. That’s because we live and think in the present and we take asphalt, rock, concrete, timber and steel for granted. Truth is, the damage is mostly done before it is installed.

Think about it, where did the raw ingredients come from? and happens to them then? where are they going next? Every step of the way, creating these materials causes damage that we don’t see. By damage I mean the likes of destruction of habitat, contaminating air, soil water, and the energy used the create raw materials into asphalt, rock, concrete, timber or steel.  Energy is used as a measure of impact because in order to create usable energy we burn coal, oil, dam rivers, build giant wind turbines and in some countries, use nuclear power (not in NZ). Each of these methods releases a lot of greenhouses gases, primarily CO2 but also others that are measure as equivalent to CO2.

Through their useful life span, asphalt, rock, concrete, timber and steel may have a positive contribution to our environment but what about the end? When your structure needs to be deconstructed, destroyed and dumped. What is the impact then? It is complicated to measure all this stuff to work out which material is the best and worst but clever scientists and mathematicians across the world have been collecting data and building models (math ones) using a recognised method called Life Cycle Analysis (LCA).

I did several weeks of research and calculating using their data to compare these five materials used in landscapes… sometimes called hardscapes. It turns out that the worst offender is actually marketed as an environmental choice! Can you guess which one it is?