5:15 PM - 6:45 PM
[AGE29-P03] Comparative evaluation of evaporation efficiency of permeable pavement blocks made from recycled concrete and autoclaved aerated concrete at different design porosity
Keywords:permeable pavement block, autoclaved aerated concrete, evaporation efficiency, solar reflectance, urban heat island
Due to rapid urbanization and population growth, the generation of construction and demolition waste (CDW) including concrete waste and autoclaved concrete (AAC) waste is increasing in developing countries. The urbanization as well as global warming cause. The urban heat island (UHI) problem. Permeable pavement (as well as water retentive pavement) contributes to mitigate the UHI effect decreasing the road surface temperature in urbanized areas and in widely spread in developing countries. The permeable pavement, however, has not been fully adopted in most of developing countries including Vietnam due to lack of reuse/recycling of CDW.
In previous studies, therefore, investigated the evaluation efficiency and solar reflectance of permeable pavement blocks made from recycled concrete aggregates (RCA) blended with AAC grains, aiming the promotion of the CDW reuse/recycling and the mitigation of UHI at urbanized areas in Vietnam. In a climate-controlled room, evaporation efficiency of tested samples was measured following a standard method (JSTM H 1001, 2015) and solar reflectance and thermal conductivity were also measured under the evaporation process. The measured evaporation efficiency and solar reflectance for permeable blocks with design porosity of 20% blended with AAC grains satisfied well the Eco-standard of permeable and water-retentive interlocking blocks in Japan.
If water retention and strength can be increased by reducing the design porosity, then more CDW can be used. From recycling perspective, it is effective that more CDW can be blended. So, in this study, the same experiment is performed on a block with design porosity of 15%. Then, the relationship between the design porosity and evaporation performance is investigated. Four types of permeable blocks with design porosity of 15% were prepared by changing the blending proportions of AAC grains (0,5,10,15%). As control blocks, a permeable block and a water-retentive block (K-Ground Coat block, ECOSYSTEM Co. Ltd., Japan) were used.
The results of the design porosity comparison between 20% and 15% are that the blocks with design porosity of 15% has greater evaporation efficiency and lower surface temperatures than the blocks with design porosity of 20%. Blocks with design porosity of 20% tend to behave more like water-retentive blocks. Further studies are needed to examine the relationships between mechanical properties such as compressive and flexural strengths and the design porosity.
In previous studies, therefore, investigated the evaluation efficiency and solar reflectance of permeable pavement blocks made from recycled concrete aggregates (RCA) blended with AAC grains, aiming the promotion of the CDW reuse/recycling and the mitigation of UHI at urbanized areas in Vietnam. In a climate-controlled room, evaporation efficiency of tested samples was measured following a standard method (JSTM H 1001, 2015) and solar reflectance and thermal conductivity were also measured under the evaporation process. The measured evaporation efficiency and solar reflectance for permeable blocks with design porosity of 20% blended with AAC grains satisfied well the Eco-standard of permeable and water-retentive interlocking blocks in Japan.
If water retention and strength can be increased by reducing the design porosity, then more CDW can be used. From recycling perspective, it is effective that more CDW can be blended. So, in this study, the same experiment is performed on a block with design porosity of 15%. Then, the relationship between the design porosity and evaporation performance is investigated. Four types of permeable blocks with design porosity of 15% were prepared by changing the blending proportions of AAC grains (0,5,10,15%). As control blocks, a permeable block and a water-retentive block (K-Ground Coat block, ECOSYSTEM Co. Ltd., Japan) were used.
The results of the design porosity comparison between 20% and 15% are that the blocks with design porosity of 15% has greater evaporation efficiency and lower surface temperatures than the blocks with design porosity of 20%. Blocks with design porosity of 20% tend to behave more like water-retentive blocks. Further studies are needed to examine the relationships between mechanical properties such as compressive and flexural strengths and the design porosity.