A new path for paving

Asphalt is asphalt, right? Well, no, at least not for much longer. Recent innovation promises to change the way we surface roads for ever.

In western countries, roads cover up to 5% of the inhabitable surface area. They also make use of a high proportion of fossil fuel deposits such as tar. While asphalt can generally be recycled well, the tar slowly poisons the ground, and roads are energy-intensive to make anyway. So what can be done about this?

Lynpave is a development which uses by-products from agriculture and the wood processing industry as filler for asphalt. Using lignin as a bio-based bulk material, the asphalt mixture has a significantly lower environmental impact.

This is due to the production temperature of under 100°C, which is around 30% to 40% lower than that used for regular asphalt. This results in lower fuel consumption and reduced CO2 emissions. The material should also be longer-lasting than conventional asphalt. It consists partly of recycled, milled asphalt. By adding the lignin, the aging binder is ‘rejuvenated’, extending the lifespan of the material.

Currently, the resulting material is produced as pressed, sand-coloured and rounded blocks. Almost any green matter can be added to Lynpave; a consortium of manufacturers has experimented with tree bark, grass, saw-dust and wood-shavings and flax.

In simulation tests, the biobased additive influences the material’s physical characteristics positively. Toughness and weight-reduction mean that the total asphalt layer can be thinner, too.

The long-term consequences of using bio-based supplements are far from simple, however. Using more material from agriculture increases pressure on farmland, which can lead to erosion and to the land becoming unsuitable for growing standard crops.

Still, any development that leads to a cleaner environment is laudable. We can now look forward to roads which will be increasingly green, even though they look dark grey.


Images via creative commons licence.