Worldwide an increasing migration from rural to urban regions can be observed. Hence cities are growing and as a result the building density and the land sealing rise. Concrete as commonly used building material in urban structures provides a high heat storage capacity. Therefore the microclimate in cities has become warmer than in the surrounding areas. This phenomenon is called Urban Heat Island Effect. To mitigate this situation a large scale application of self-cooling concrete pavers is an approach to reduce the urban heat island effect. Making use of evaporation enthalpy, this new type of pavements counterbalances the absorption of solar radiation and the subsequent transfer of heat to the surrounding environment. The typical double-layer structure of concrete paving stones can be maintained. The mass concrete acts as a water storage layer and is covered by a permeable face concrete. As the different requirements of these layers demand different concrete mixtures, they are developed and optimised for their respective functions. This paper presents some suitable no-slump concrete mixtures that combine a sufficient compressive strength as well as good water transportation properties for the above mentioned approach.
Rising temperatures worldwide pose an increasing challenge for safe and healthy living conditions. Particularly inner cities have been affected by these environmental changes because of the materials used to build houses, streets and infrastructure. The most common building material is concrete. It shows a specific heat capacity, while the heat conductivity for Standard concrete is low. Thus, the use of concrete generates a high capacity of heat storage. In addition, extensive soil sealing also contributes to the temperature rise of inner city areas compared to
their surroundings. To mitigate this so-called urban heat island effect, a self-cooling concrete paver was developed. This paver is able to store water. The evaporation of the water at elevated temperatures provides a cooling effect. This paper focuses on determination of this new paver’s capability to cool the surface and the surrounding. The new paver’s cooling Qualities were analysed in a series of laboratory tests. To prove the results outside of laboratory conditions, two fields (12 m × 8 m) with self-cooling and reference pavers were installed in Spain.
This paper presents and discusses the results of the tests. Correlation between reduced surface temperature of the self-cooling concrete pavers and the air temperature is examined.
In the last several decades, the rural exodus has led to an increasing number of inhabitants in the urban areas. The increased building and infrastructural construction caused the transformation of the landscape and to an increased land sealing in these areas. Consequently, the increased land sealing influences the air temperatures in the cities, since houses, streets and squares heat up continuously. As a result, the city and metropolitan areas became significantly warmer than their surroundings - the effect is known as Urban Heat Island (UHI). These changes have a negative impact for the quality of life. To deal with the negative effects of UHI, a high level of technical and financial effort is necessary. The costs caused by the UHI effects are in the range of several billion US dollars worldwide per year. The recent studies on UHI showed that the established methods like parks and green spaces or bright coatings for roof areas will soon not be able to effectively cope with the UHI effect in urban areas. Therefore there is a need for additional methods to mitigate UHI effect in the cities. The streets, sidewalks and squares represent approximately 30% to 40% of the inner cities areas. If these areas are designed functionally, they can have a significant impact on the UHI. This contribution focuses on development of a concrete paving stone with self-cooling properties. For the cooling effect the evaporative cooling is used. The paving stone is able to store large quantities of water and deliver during appropriate environmental conditions. This paper deals with the results of the long-term experiments on the test-fields under different climatic conditions. To interpret the test-field-results, laboratory tests were carried out as well. The paper presents and discuss the obtained results, and points out the difficulties occurred.