Apr 21, 20213 min
Tori Scott reports on how waste paper could be beneficial for making road construction more sustainable for the environment.
Photo by Levi Meir Clancy
Although the production of paper and pulp is increasing worldwide, which means that waste is too, researchers at the University of British Columbia Okanagan are working to make this waste material useful in public infrastructure.
“Anytime we can redirect waste to a sustainable alternative, we are heading in the right direction” – Dr Sumi Siddiqua, UBC associate professor
More specifically, they are investigating whether wood-based pulp mill fly ash (PFA), a non-hazardous commercial waste product, has the potential to be used as a construction material for products such as bricks, cement-based materials, mineral filler, geo-polymers and composites.
1. Resource Depletion
For concrete to strengthen, it requires a balanced mixture of rock, sand and fabricated cement component. The process of obtaining these materials and applying them to the roads is a very resource intensive process. Re-using existing concrete and asphalt by remixing it with virgin materials allows for industries to decrease that resource depletion.
In addition, asphalt is a petroleum-based product. To produce both asphalt and concrete it requires a lot of energy, so finding ways to reduce this use of energy is vital to minimise the ecological impact of public infrastructure and architecture.
2. Water Pollution
Road and parking lot construction projects have to be innovative and elaborate with drainage networks to remove rainwater from surfaces and prevent any flooding from occurring on the building sites. If drainage networks are not in place, it brings the risk of exposing water to pollutants, surface debris and asphalt. Any polluted water will flow into municipal sewage networks and empty into lakes, rivers and streams.
3. Harmful Atmospheric Emissions
The process to make asphalt releases harmful gases into the atmosphere. Furthering this issue, curing applied asphalt adds more harmful emissions to the air. Producing cement for concrete requires significant amount of heat, additionally generating substantial volatile organic compound emissions.
Most of the time, waste materials from paper and pulp end up as landfill. However, as the Canadian researchers have shown, there could be significant uses for them in construction, agriculture, and energy. For construction, paper and pulp waste could be used as possible fillers for building products.
If ashes, green liquor dregs, skater grits, lime mud and pulp mill sludge are disposed of improperly, it can lead to structural changes of the ecosystem through water wastewater treatment otherwise known as “eutrophication”.
“The porous nature of PFA acts like a gateway for the adhesiveness of the other materials in the cement that enables the overall structure to be stronger and more resilient than materials not made with PFA” – Dr Chinchu Cherian
It has been proven that the pulp and paper mill industry could have high potential for sustainability, but using the pulp and paper by-production like black liquor could also displace a portion of fossil fuel use. As such, changing this industry is not only important for improving sustainability in construction but also in decreasing the pollution of the environment.
Although there have been a number of concerns that the toxins used in pulp and paper mills could drain out of the recycled material, this has been disproven by Dr Siddiqua:
“the use of the untreated PFA is so strong, little to no release of chemical is apparent. Therefore, it can be considered as a safe raw material for environmental applications”
As of the end of last year, human-made materials now outweigh the combined mass of all living matter – and a large proportion of this is asphalt and concrete. Any innovation in making construction materials even a little more sustainable is therefore important in reducing the impact of urban development as the world's population continues to grow.
Article on a similar topic: Human Materials to Outweigh the Earth’s Entire Biomass
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