Newly developed photocatalytic concrete could help roads clean up air pollution

Could our roads defuse harmful compounds created by the cars that run over them? Engineers at KICT demonstrate an experiment capable of cutting down air pollution.
Amal Jos Chacko
Representational image of a tunnel
Representational image of a tunnel


It is common knowledge that traffic is one of the biggest culprits pulling down the quality of the air we breathe in. Their adverse effects echo louder in scenarios with a lot of cars and little air circulation, like in an underground road tunnel.

Sure, replacing these gas-guzzling machines with their hybrid and electric equivalents could go a long way in curbing air pollution, but there remains a need for other approaches as well.

When fuel is burnt at high temperatures, a group of nitrogen oxides is emitted, which can potentially react with other pollutants to form smog and thus affect our health.

Recent research published in the KSCE Journal of Civil and Environmental Engineering Research in 2021 investigated the removal of these oxides by the use of photocatalytic porous concrete.

Engineers at the Korea Institute of Civil Engineering and Building Technology (KICT) built upon this research and demonstrated that photocatalytic concrete can reduce pollution in tunnels.

Newly developed photocatalytic concrete could help roads clean up air pollution
A diagram illustrating how the new air-purifying concrete works.

Photocatalysts are materials that initiate reactions when exposed to light

The team engineered concrete coated with titanium dioxide which produces molecules called reactive oxygen species (ROS) in the presence of sunlight.

These are unstable molecules with one or more unpaired electrons, making them highly reactive and capable of breaking down air pollutants, especially volatile organic compounds (VOCs), nitrogen oxides, sulfur oxides, and ammonia, rendering them harmless.

KICT’s Green Construction by Photocatalyst Research Group (GCP), a pioneer in developing cost-efficient photocatalysis technologies from wastewater sludge, experimented with an application of photocatalytic concrete in the Banpo Underground Road Tunnel in Seoul, South Korea.

The underground tunnel proved to be prime for this experiment due to poor circulation and frequent traffic. Additional artificial lights were installed to accelerate light-activated reactions in areas unreachable by natural light.

The team observed levels of nitrogen oxides to drop by 18% over 24 hours. Salts formed in the concrete as a result of the reactions were washed away by rain, hinting at the process of functioning indefinitely and requiring virtually no further maintenance beyond that of regular concrete.

“Construction technology using photocatalysts can have an immediate effect on reducing fine particulate matter in the nation’s living environment. We plan to build a system of cooperation with local governments and public corporations to expand trial demonstrations to other sites to achieve commercialization and distribution with practical effects,” said Dr. Jong-Won Kwark, head researcher on the project.

The team intends to continue its research and explore commercialization while building its effectiveness.

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