Air-cleaning paving blocks convert air pollutants from vehicles into non-hazardous substances.

The Hong Kong government is vigorously promoting the Action Blue Sky Campaign (please refer to News No. 178 for details), in the hope that this new series of measures will enhance air quality in Hong Kong.

One recent innovation that could help further this goal is the air-cleaning paving block. Unlike common concrete blocks, the new paving blocks have a 5mm titanium dioxide coating. In the presence of sunlight, this coating acts as a catalyst to transform pollutants like nitrous oxide from car exhaust into nitrates that are not harmful to the environment. Tests showed that these air-cleaning blocks can remove 20 percent of air pollutants. This innovation won the Hong Kong Eco-Products Award and Green Building Award in 2006. Exhibited at the Hong Kong Innovation & Design Expo in November Golden Year 3 (2006), the blocks’ design is credited to the research of Lam Chi Sin, Chan Chun Wan and Wong Chi Ho of Hong Kong Polytechnic University.

These three youths have shown tremendous creativity and a strong passion for environmental causes. They have secured a local technology patent for their innovation and an agreement from their university to manufacture the paving blocks, establishing Laputa Eco-Construction Material Company, Ltd., to produce the blocks locally and to sell them.

Air-cleaning paving blocks not only effectively help protect the environment but are manufactured from environmentally friendly materials that include glass beads, ash from coal-fired power plants, and gravel. The glass beads are made from mechanically crushed recycled glass bottles and crushed sand acquired from construction waste, thereby also reducing the waste disposal needs for the local government. Laputa’s environmental concept has also attracted corporate interest and it now receives some of its glass bottles from Coca-Cola.

There has been concern that the titanium dioxide coating may slowly wash away. However, the surface layer of the blocks is a blend of titanium dioxide and concrete, which can last 10 to 20 years when exposed to natural elements as well as human and vehicular pressure.

The blocks have an anti-slip properties and are resilient to pressure. They are made to withstand a weight of 60 tons on sidewalks and 90 tons on roads. Their wide variety of designs, environmentally friendly properties and low cost have ensured their wide use in Hong Kong.

References:
http://hkheadline.com/news/headline_news_detail.asp?id=19410&hl=%BFj&section_name=wtt (Chinese)
http://www.cse.polyu.edu.hk/~cecspoon/gd.pdf (English)

Hong Kong’s three young innovators (from left to right): Chan Chun Wan, Lam Chi Sin and Wong Chi Ho, who have successfully developed air-cleaning paving blocks to support the government’s Action Blue Sky Campaign.	Roads on the Chinese University of Hong Kong campus are paved with air-cleaning paving blocks.

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