Eco-Block

Eco-Block, which was invented by the Hong Kong Polytechnic University in 2006, is an environmental friendly brick made from recycled materials and construction waste. The major feature of Eco-Block is to catalyze the nitrogen oxide and other pollutants in air into non-hazardous substances. Eco-Block has been mainly used as paving brick in pedestrians and vehicular areas in Hong Kong and it is now the 3rd generation.

The major constituents of the Eco-Block are recycled glass and recycled aggregate from construction and demolition waste. Apart from that, a small quantity of is used on the surface layer of the eco-block.

A mechanized molding method is used for producing the Eco-Block. The materials are mixed with water and fly ash in a fixed proportion. Then the mixed materials will be molded under a combined vibrating and compacting action. Before put into use, the eco-block needs to be cured under suitable condition.

On the surface layer, there is a special coating made from titanium oxide (TiO2). When activated by the sunlight, the titanium oxide can catalyze the decomposition of nitrous oxides into oxygen, water, sulphur, nitrates and other non-toxic solid compounds which can be washed away by water.

Eco-Block has currently undergone three generations and each generation has a slightly different composition. In general, all the generations made up of local construction waste. In the second generation, recycled glass powder from recycled glass bottles were added in the incorporation in Eco-Block for making its outlook more appealing and providing a wider range of usages of it. In the third generation, a photo-catalyst was added in the production process which catalyzes a chemical reaction and helps improve the air quality in Hong Kong.

Eco-Block is a construction material and its surface layer is made of sand, glass sand, fly ash and cement while the base layer is made of coarse aggregate, sand, glass sand, fly ash and cement.

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