ROAD DIVIDERS, TUNNELS and Traffic Infrastructure

 

Road dividers, noise barriers, bridges, overpasses and tunnels are exposed to high levels of traffic pollution. Cleaning and maintenance typically involves restricting traffic, but is necessary: reducing biofilm growth and water uptake increases durability of concrete structures, and cleaner surfaces also contribute to traffic safety. 

Night, rain and fog makes for poor visibility. Cleaner and brighter roadside surface give better contrast which makes driving easier and helps identify and prevent potential dangerous situations. Driving through a light grey or white tunnel is just much more comfortable than driving though a dark one – and the same reasons apply outdoors. Joma treated concrete gives much less darkening when wet, which is most of the autumn and winter.

Air pollution from traffic is not just a question of dirty surfaces, but also a human health issue.  NO2 from cars is a main contributor in poor urban air quality, society need to look at solutions beyond car emission regulations. A photocatalyst with high NO2 selectivity is a solution, and roadside surfaces such as noise barriers and road dividers are ideally suited for coating since they are close to the pollution source and relatively undisturbed.

Joma is located in Bergen, Norway, where the climate is wet, winters are dark, and poor air quality in winter has become a major political issue. We are conducting long-term field tests of air purifying, low maintenance coatings in cooperation with local and national road authorities.

 

  • ·         PROBLEM: Maintenance requires stopping traffic. Air pollution is a serious health issue, but hard to control without severely restricting traffic.
  • ·         SOLUTION: Joma offers solutions for protection and reduction of maintenance on traffic infrastructure, including self-cleaning and waterproofing concrete treatments as well as easy-clean tunnel paint. The patented nanoparticle structure has record high selectivity in breaking down pollutants from traffic.

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PAVEMENTS and PLAZAS

 

In urban areas, there are large paved areas with cement pavers or natural stones. These are typically cleaned regularly by maintenance vehicles but there are still problems with biofouling. Urban areas also tend to have inferior air quality –  an related problem, but one with the same solution: photocatalysis. However many photocatalytic coatings do not work very well under these conditions: abrasion from machine cleaning will quickly remove any surface layer that does not have extreme hardness and adhesion. Even just the wear and tear from pedestrians may be too much for some products.

Joma offers solutions for paving stones that embed into the pores of the concrete where it is protected from abrasion. This is even the case for the Joma Hydro products, where both the photocatalytic and water-protecting layers are protected from wear. Since the pores have a large total surface area, this adds to the efficiency of the product as long as the pores are open. Dirt and dust can clog the pores, but the hydrophilic pores in the active layer help water penetrate below such fouling and wash it out. For this job, machine washing and protective coating play on the same team.

To clarify: the surface cleaning is eased by the hydrophilic property of the active titania, while the pores further in are hydrophobic to stop water from penetrating. This deliberate combination of opposite properties is part of what makes our products unique.

  • ·       PROBLEM: Protective coatings are worn away by machine cleaning and normal wear. Without washing, inorganic dirt and dust blocks the self-cleaning activity.
  • ·         SOLUTION: Joma photocatalytic coatings penterate into pores and is not washed off. Air and surface cleaning effects work well in combination with normal cleaning.

 

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BUILDING FACADES and ROOFS

Everyone who owns a building knows that we prefer them to look good, but maintenance can be a lot of work. Even ‘indestructable’ materials like stone, concrete and silicate paint eventually get covered in growth, and buildings don’t need to be very tall before washing the façade becomes a complex operation. Roofs are even worse; unreachable from the ground for cleaning, but collects dead leaves and airborne spores and have plenty of rainwater and sunshine to support growth.

Fortunately, walls and roofs are among the easiest tasks for photocatalytic self-cleaning! Vertical and angled surfaces have no problem with water pooling but instead rain helps wash away degraded material. The good access to sunshine that would otherwise speed up growth, instead speeds up the anti-greening. The drainage pipes still need to be cleared out, but even this is improved since the rainwater picks up less contaminants from the roof itself.

Joma offers products for concrete walls and roof tiles, including the Hydro product seriess. For business customers we can also develop solutions for painted surfaces and variant rooftile materials.

  • ·         PROBLEM: cleaning is cumbersome/costly, particularly for large buildings.
  • ·         SOLUTION: Joma photocatalytic coatings reduce need for cleaning

 

 

 

 

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Urban AIR PURIFICATION / de-NOx

 

NOx pollution from traffic is a serious public health problem. EU has passed strict regulations for air quality standards. However, despite stricter emission limits for new cars, total pollution continues to increase. The European Enivronmental Agency estimates that NO2 pollution causes 75000 premature deaths in EU every year, and many cities are looking for other solutions than just restricting traffic.

Biofuels can cut the CO2 footprint of the fuel production cycle, but emit the same amounts of NO2 and PM. Electric cars are a good long-term solution, but it will take more than a decade to replace the existing cars, and electric trucks still have far to go to be competitive . What we really need is technical solutions for directly improving the air quality, independent of, and in addition to, behavioral changes by individuals and companies.

One proven solution is photocatalysis, and NOx-degradation is the test standard for photocatalytic activity. However, good performance in the ISO test does not necessarily mean good results in field tests. Part of the answer is blowing in the wind: the air purified from blowing along a treated surface is not necessarily the same as the one reaching the NOx sensor, and coating your own wall will likely benefit your neighbours more than yourself. Successful projects must take air flow patterns into account when deciding where to coat and how to measure the effect.

Another key factor is the way the ISO test is set up. A material can get a very high activity score by transforming NO to NO2 without actually breaking down the NO2. Since the health problem is the NO2, the best material has not just high activity but also very high NO2 selectivity[link]. This is a an important detail: a material with “high activity” that transforms NO to NO2 faster than it transforms NO2 to nitrates will give more toxic NO2 in the air. That material is not necessarily bad for other photocatalysis applications, but for air purification it will just make matters worse.

Joma nanoparticles have a patented surface composition which gives a very high NO2/NOx selectvity compared to other commercial photocatalytic particles.

 

  • ·         PROBLEM: Good lab results does not equal good field performance. Breaking down the wrong molecules adds to the problem.
  • ·        SOLUTION: Use Joma nanoparticles with record high selectivity for NO2 degradation. Take flow patterns into account when deciding where to treat and where to measure.

 

 

 

 

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GARDENS and PARKS

 

In a garden or park, growth is all around and hard to contain. Walls and stone paths quickly become green unless dilligently maintained. Compared to buildings and roofs there is good access for cleaning, but the growth rates are so high that maintenance can still be a problem. High growth and corresponding maintenance costs leads to landscape architects using tarmac instead of more aestehically pleasing stone and concrete.

From a self-cleaning point of view, gardens are more difficult than buildings since there is simply much more growth to control. A strength of photocatalysis is the breaking down of growth before it has a chance to take proper hold, meaning that even in very tough conditions the surface stays clean longer, reducing maintenance frequency.

  • ·         PROBLEM: High biological loading, growth all around that spreads to walls and paths.
  • ·         SOLUTION: Joma photocatalytic coatings reduce need for cleaning

 

 

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