Material Flow Analysis of Construction and Demolition Wastes in Taiwan and their Sustainable Management

Construction is like a symbol of social development. Buildings and public infrastructures are required to support people's lives and a country's development. With the increasing construction, the waste of construction increases as well. Demolition wastes from existing buildings or urban renewal plans also increase the waste quantity. Construction and demolition wastes (CDW) are majorly inorganic materials and have high recycling potential. However, the recycling rate of CDW is not 100% and needs more methods to raise the rate. In Taiwan, the CDW has two authorities, one is CDW waste managed by the Ministry of Environment (MoE), and the other is construction spoil soils managed by the National Land Management Agency, Ministry of Interior. In 2022, the CDW waste is 2.12 million tons, and construction spoil soils are around 43 million m³. In this study, the current status of CDW in Taiwan was reviewed and material flow analysis was applied to link the materials sources to CDW. The results showed that 35% of waste concrete flowed back to the source materials and 65% was disposed of or used as secondary materials. However, 95% of waste steel was used back as raw materials and only 5% was disposed of or used in other materials. To increase the recycling of CDW, the priority method is to force the material separation onsite. Mixing CDW would increase the cost of recycling and decrease the market competition ability. New technology to collect and recycle the CDW as a new material is also recommended. Finally, a new law, the Resources Recycling Promotion Law, is coming in this year, 2024, which is expected to turn the waste into resources in Taiwan.