Sunday, 10 December 2017

Phototcatalytic concrete


Photocatalytic Concrete


The word photocatalysis is a compound word made up of 
(1) photo or light and 
(2) catalysis or acceleration of a chemical reaction rate by addition of a catalyst. 

A catalyst is a substance which although combines with the reactants participating in a chemical reaction but remains unaltered. Hence photocatalysis is a reaction which uses light to accelerate the rate of a chemical reaction without being involved itself. Photocatalytic cements can be used as substitutes of traditional Portland cements, with no modifications in rheology, mechanical strength and structural performances of concrete products. 
Photocatalytic materials are not a total solution for the elimination of the pollution in urban environments, but can contribute for an effective reduction of gas concentration.



Some Recent Construction:
The new Jubilee Church in Italy, The Air France headquarters at Roisy Charles de Gaulle airport at Paris and the Hotel de Police in Bordeaux France have been constructed of photocatalytic concrete. In Japan, photocatalytic precast concrete pavements are constructed to depollute car exhausts.


Photocatalytic cement-based products :
  • Ready-mix concrete
Walls, columns, beams, pavements 
  • Precast concrete
Panels, columns, road barriers, sound-absorbing panels, paving blocks, slabs, tiles, GFRC (Glass Fibre Reinforced Cement) 
  • Pre-mix (coatings) 
  • Paints (thickness: 0.3-0.4 mm),Skim coats and fine coating(1-3 mm), renderings(8-15 mm).


Materials Used For Making Concrete:

When a photocatalyst is incorporated in a concrete, it decomposes organic materials like dirt, mould, algae, bacteria, allergens, air pollutants, smoke, tobacco etc in the presence of light. The catalysed compounds break down into oxygen, carbon dioxide, water, sulphates, nitrates, and other substances that are either beneficial or have a relatively minor effect on the environment. This type of concrete having a photocatalyst in it is known as photocatalytic concrete or self-cleaning concrete, which is a green construction material.

A photocatalytic concrete along with its structural qualities like an ordinary concrete is a strong depollutant. Titanium dioxide (TiO2) or titania is the photocatalyst material mixed with the concrete. In the presence of light, titania creates a charge that disperses on the surface of the photocatalyst, and reacts with external substances to decompose organic compounds. The products of the reaction can easily be washed with water. Rain or simple rinsing can easily remove the reaction products and the building looks clean and beautiful like a new one. Titanium dioxide can be employed in all types of concrete, including plaster and mortar.

Along with TiO2, other photocatalysis like ZnO, WO3, FeTiO3 and SrTiO3 can also be utilised in concrete for the same purpose. As the sunlight strikes the concrete surface, most organic pollutants are neutralised; this would otherwise discolour the concrete surfaces. As already mentioned, the photo catalyst is not spent as it breaks down the pollutants, rather it continues to work indefinitely.

Special Applications Of Concrete:

  • This technology represents one of the most innovative solution 
  • in cement industry, over the last twenty years 
  • Sustainable materials, for the future
  •  “Green” technology for high quality solutions
  •  Depolluting technology for urban environments
  • Durable materials for long lasting buildings
  • Increasing market (2010: 3,500 tons – 2011: 4,000 tons) 
  • Over 2,000,000 m2 of “active” surfaces 
  • Italcementi Group (ITC): Strong R&D activity for strengthening in the photocatalytic products in the building sector
  •  International networking with other Industries, Universities, and R&D Centres
  •  Continuous market survey to check possible infringements in defence of ITC patents portfolio
  • Active participation to International and National standardisation works (CEN, ISO), including round-robin tests.

Reference:
Journal of Chinese Ceramic Society Vol 42, No 5, May 2014. 


Phototcatalytic concrete

Photocatalytic Concrete The word photocatalysis is a compound word made up of  (1) photo or light and  (2) catalysis or...