Construction and demolition waste as drainage in landscaped roofs

Abstract

Since 1990, the world has seen an increased gathering of its population in urban areas. this trend is not new, but relentless and has been marked by a remarkable increase in the absolute numbers of urban dwellers. In 1990, 43 per cent (2.3 billion) of the world?s population lived in urban areas, by 2015, this had grown to 54 per cent (4 billion). As the urban population increases, the land area occupied by cities has increased at an even higher rate. it has been projected that by 2030, the urban population of developing countries will double, while the area covered by cites would triple. Thus, cities must play a greater role, because urban areas have the potential to reduce ecological footprints and to connect rural and natural environments , and this is the reason why cities are included in the 2030 agenda for sustainable development, in the goal 11: to make cities and human settlements inclusive, safe, resilient and sustainable. In this sense, green or landscaped roofs can be an important asset for the recovery of disused spaces in the city, and an opportunity for the development of more sustainable cities. In addition, the incorporation of vegetation into the urban system generates benefits in all three aspects of sustainability: social, economic and environmental. On the other hand, and according to the UK Green Building Council the construction sector uses more than 400 million tons of material each year, much of which has a negative environmental impact. Therefore, in recent years there have been numerous researches that have aimed to find alternatives for construction and demolition waste trying to replace the costly raw material for the environment and incorporate Circular Economy criteria in the sector, but after a detailed bibliographic and documentary search, no studies have been found that attempt to analyze the possible replacement of the drainage layer of the landscaped roofs with construction and demolition waste, the objective of this study. Therefore, an experimental plan in two phases was designed. In the first phase, the ceramic wastes were selected, and their physical properties (density, water behavior), as well as their leachate were analyzed. In a second phase, the capacity of these materials as a substrate is checked. The results of the experimental plan were that waste from ceramic elements have a greater capacity for water absorption, which means a better use of rainwater and even the decrease of the water necessary for cultivation, especially matter of much interest for roofs located in dry climates.