Nanotechnology for Combatting Climate Change: Construction Materials

Construction materials—such as concrete, cement and asphalt—are some of the world’s most widely used materials and major contributors to carbon emissions.

And their use won’t be reduced in the future, as humans must create new buildings and roads in the face of an ever-growing population.

Concrete alone accounts for 8% of all carbon emissions today. Cement, a key ingredient in concrete, is also the most widely produced man-made resource in the world – over four billion tonnes are produced annually.

Given the continued use of both cement and concrete, as well as asphalt (created from petroleum for use in roadbuilding) these materials must be made more environmentally friendly to fit modern-day sustainability goals.

This is where nanotechnology comes in and specifically the carbon derivative, graphene, as there are already concrete and cement products on the market that contain graphene and are much more environmentally friendly.

Commercialisation of graphene asphalt is not as widespread, but several successful real-world trials in the UK and EU, mean it won’t be long before this reaches the same level as other graphene-enhanced construction materials.

Graphene-Enhanced Concrete and Cement for Reduced Carbon Emissions

Concrete is strong and low cost, so it is the ideal construction material, but it degrades over time and a lot of material is generally needed to bear large loads.

Introducing a small amount of graphene (usually less than 1%, and often just 0.1% of the whole) into the cement or the overall concrete mix can deliver several longevity benefits, including a 25% increase in tensile strength, a 35% increase in compressive strength, and a four-fold increase in water resistance.

These improved physical properties also mean a smaller amount can support a greater load; structures created to date with graphene-enhanced concrete have required 33% less material to deliver similar structural properties and durability.

By simply reducing the material volume required using graphene, it’s thought that concrete’s 8% global carbon footprint could be lowered by as much as 2%.

There are already several companies manufacturing graphene-enhanced cement, graphene-enhanced concrete mix, or graphene admixtures for existing concrete products.

Key players with products on the market or at the prototype stage include Global Graphene Group (GGG), Bio Graphene Solutions (BGS), GtM Action, C&O Concrete, First Graphene Limited, Haydale, Graphenea, and Black Swan Graphene.

Improving the Longevity of Roads with Graphene

Work on graphene-enhanced roads has largely been collaborations between government bodies and private companies, so while the materials are not necessarily available to the public, a lot of work is being done to bring graphene-enhanced roads to different countries - several roads in the UK and Italy have already had graphene treatment.

The first successful graphene road trial used a 1km stretch of road outside Rome in Italy through collaboration between Italian construction additives manufacturer, Iterchemica, and graphene producer, Directa Plus. After this, further graphene roads were laid at Rome's Fiumicino airport.

The initial trial showed how graphene-enhanced the service road’s life-fatigue resistance by over 250%, indirect tensile strength by 35%, and resistance to deformation by 46%, while reducing the permanent plastic deformation by 35%.

Graphene also imparts high thermal stability into the asphalt, making it better at dissipating heat and dealing with increasing road temperatures from prolonged hot spells caused by climate change.

Since the success in Italy, several UK trials have been launched: the first was a 750m stretch of road in Curbridge, Oxfordshire, in conjunction with Skanska and Directa Plus, with reports of an increased road lifespan of up to 70%. This success led to a second trial in Oxfordshire on Marsh Lane in Oxford.

Directa Plus and Skanska have also worked with the UK Department of Transport on resurfacing East Hill in Dartford, Kent, with results showing resurfacing with graphene roads could cost up to 32% less than conventional asphalt in the long run.

There has also been a big project on the A1 in the northeast of England, on the northbound carriageway between Newton on the Moor and West Cawledge,  involving Britain’s National Highways authority, the Graphene Engineering Innovation Centre (GEIC), and Pavement Testing Services (PTS).

The existing road surface was dug up, and graphene added to the recycled asphalt, which was then re-laid, becoming the longest stretch of graphene-enhanced road trialled to date with 5km (3 miles).

As with graphene-enhanced concrete and cement, less material is required than standard asphalt to reap the same benefits, so it is more environmentally friendly and cost-effective in the long term.

The graphene not only improves the road’s longevity but leads to less vehicle damage through fewer potholes and better road conditions.

Trials continue, but there is great future potential for renewing or creating road systems that are longer-lasting and greener.

Written by Liam Critchley