Project Overview
Since 2015, Taoyuan City has been incorporating recycled materials including oxidized slag, reclaimed asphalt pavement (RAP), incinerator bottom ash, and waste tires in public works projects. From 2016 through 2023, the city has utilized approximately 164,000 metric tons of oxidized slag, 396,000 metric tons of RAP, 375,000 metric tons of incinerator bottom ash, and 4,000 waste tires. Taoyuan also pioneered Taiwan’s first circular economy management platform for recycled materials, establishing comprehensive oversight from source control to recycling and material tracking.
Taiwan generates approximately 3 million metric tons of furnace slag, 5 million metric tons of reclaimed asphalt, 1 million metric tons of incinerator bottom ash, and 150,000 metric tons of waste tires annually. The lack of proper disposal solutions for these materials has forced steel mills to reduce production, halted public construction projects, and disrupted household waste collection services, resulting in substantial economic losses and serious disruption to daily life. To address these waste management challenges, Taoyuan City Government has implemented innovative construction methods to transform waste materials into viable construction resources for public works projects, promoting sustainable recycling while reducing natural resource extraction.
The Taoyuan City Government aims to not only expand the use of recycled materials but also build confidence among contractors and the public in using these repurposed resources. The city has revised construction specifications, developed user manuals, and established the “Taoyuan City Guidelines for Using Recycled Aggregates and Green Building Materials in Public Works.” These initiatives promote effective resource recycling, reduce construction costs, address industrial challenges, and advance Taoyuan’s development as a sustainable, low-carbon city.
Implementation Benefits
(1) Implementing Circular Economy to Achieve Environmental Protection and Sustainable Development Goals
Global annual demand for sand and gravel exceeds 15 billion tons, with Taiwan requiring over 75 million tons yearly. This consumption is second only to water usage. Sea sand extraction destabilizes underwater sand beds, while river sand mining disrupts river and coastal ecosystems, resulting in flooding and coastal erosion. By converting steel industry byproducts into new asphalt concrete materials, reusing milled asphalt in road base layers, and incorporating waste tire rubber powder in road surfaces, we can achieve zero-waste goals through recycling. This reduces extensive river and sea sand extraction, protecting ecosystems and ensuring a quality environment for future generations.
(2) Resolving Long-standing Incinerator Bottom Ash Management Issues
Taiwan primarily manages waste through incineration, supplemented by landfilling. Incineration produces large quantities of bottom ash, with the Ministry of Environment statistics showing annual production of 800,000-1,000,000 tons in recent years. Given Taiwan’s limited space and growing environmental awareness, sustainable development has become crucial. Recycling incinerator bottom ash not only reduces waste but achieves sustainable circular economy goals, addressing a major government challenge.
(3) Energy Conservation, Carbon Reduction, and Cost Savings
Using 30% steel slag to replace natural aggregates in asphalt concrete reduces carbon emissions by 1.3 KgCO2e per ton and saves NT$200 (about 3%) in material costs. Using up to 60% reclaimed asphalt pavement in road base layers reduces carbon emissions by 6.8 KgCO2e per ton and saves NT$24 (about 4%) in materials. Using incinerator bottom ash for soil improvement in a 1:1 ratio reduces carbon emissions by 3.68 KgCO2e per ton and saves NT$150 (about 15%) in materials. From 2016 to 2023, Taoyuan City Government has used approximately 935,000 tons of recycled materials, reducing carbon emissions by about 4.28 million kgCO2e, equivalent to the annual CO2 absorption of 356,000 trees.
(4) National Project - Taoyuan Aerotropolis Development’s Use of Recycled Materials
- Through circular economy and zero-waste principles, the project addresses steel and asphalt industry challenges, helping Taoyuan become a resilient city.
- Using recycled resources in construction optimizes resource circulation with short cycles (local solutions for local problems), establishing Taoyuan as a circular city.
- The Aerotropolis project includes approximately 197 kilometers of roads. Using recycled materials is expected to utilize 145,000 tons of oxidized slag, 245,000 tons of reclaimed asphalt pavement, and 314,000 tons of recycled incinerator aggregate, totaling 704,000 tons.