Trade Journals for the Concrete Industry

The increasing development and expansion of urban areas is leading to inner-city heat islands due to the creation of thermal storage masses. This phenomenon is widely known as the ‘Urban Heat Island effect’, or UHI for short. The use of self-cooling concrete paving stones could counteract this phe-nomenon. Such stones should store water, wherein this water should evaporate again when tem-peratures increase. The utilisation of the evaporation enthalpy results in a lowering of the surface temperature. If these paving stones are used over extensive areas, a reduction of the ambient tem-perature is possible compared to normal paving systems. The optimisation of the grading curves of suitable concretes should result in a good compromise between the necessary mechanical charac-teristics and good water or water vapour transport characteristics. Mixtures with equal portions of fine and coarse grains proved to be particularly suitable. The use of paper ash, a residue from the paper industry, represents one approach to the realisation of the storage of water in concrete paving stones.