Technical Paper ISSN 1996-6814 Int. J. Pavement Res. Technol. 6(4):423-430 Copyright @ Chinese Society of Pavement Engineering Vol.6 No.4 Jul. 2013 International Journal of Pavement Research and Technology 423 Assessment of CO 2 Emission Reduction in Road Construction Using Recycled Concrete Materials Kuang-Yi Wei 1+ , Jyh-Dong Lin 2 , and I-Hung Yu 3 ─────────────────────────────────────────────────────── Abstract: Climatic change is a grave threat for human life. After the industrial revolution, the rapid increase in atmospheric greenhouse gases, most notably carbon dioxide (CO 2 ), is primarily responsible for global warming over the past 50 years. Particularly, the high emission of CO 2 in civil works becomes a critical issue for urban development and construction due to its high energy demand and fuel consumption. Therefore, it is important to make the effort to reduce the CO 2 emission from each quality construction project. Based on product-category rules (PCR), two major road construction materials, asphalt concrete and cement concrete, were studied in this paper. Carbon footprints of the studied materials were examined through the cradle-to-gate life cycle assessment (LCA) from raw material mining and transportation to factory manufacturing. Our results showed that the primary factor controlling the CO 2 emission factor of recycled concrete is the proportion of recycled materials in the mixture of cement and fine-grained aggregates. The amount of CO 2 emission of road construction using recycled asphalt concrete was 4.533 kg CO 2 less than those using normal asphalt concrete. DOI:10.6135/ijprt.org.tw/2013.6(4).423 Key words: Asphalt concrete; Carbon Footprint; Concrete; Reduce Carbon Emissions. ─────────────────────────────────────────────────────── Introduction 12 Over the past half a century, the earth’s temperature has risen yearly and carbon dioxide concentration in the atmosphere continued to rise. The succession of various natural disasters is all related to the overuse of the earth’s resources [1]. In this time of climatic changes, reducing carbon emission is a common goal all the countries in the world strive for. The great energy consumption of asphalt concrete, cement, reinforcing steel, concrete and other bulk engineering materials in the manufacturing industry causes a lot of greenhouse gas emission. Asphalt concrete and cement concrete are still the main materials involved in pavement engineering, so reducing the carbon emission of these two materials will have crucial influences on the carbon emission in road engineering construction [2]. This study leads the preparation of recycled and reused concrete materials of the road engineering in the project according to the concrete code in Taiwan, carries out carbon footprint calculation and example verification, and constructs the carbon emission standards tried out by the road engineering in Taiwan. Concrete Products Evaluation Model Preparation The concrete product evaluation model is divided into the raw materials stage, factory production energy consumption stage, product transport stage, and so on according to the Product Category Rules (PCR), then the emission of the products at various stages is 11 Judong Township Office, Hsinchu County, Taiwan. 22 Department of Civil Engineering, National Central University, Jhongli, Taoyuan, Taiwan 32001.. 33 Hsinchu Science Park Administration, Hsinchu, Taiwan 300. + Corresponding Author: E-mail weiky0500@yahoo.com.tw Note: Submitted January 24, 2013, Year; Revised June 26, 2013; Accepted June 27, 2013. calculated and finally the unit carbon emission could be concluded through totaling [3]. The raw materials stage could be categorized into raw materials production and transport, while the factory production is calculated through two parts, which are the part for coordinating the design and the production process stage, respectively. Finally, the product transport stage is calculated through the motor freight investigation report and investigation results [4]. Research Object Among various concrete products, the study mainly has the two major products of cement concrete and asphalt concrete as the research object. For the cement concrete part, traditional concrete and self-compacting concrete (SCC) is the research object, while the asphalt concrete is categorized into normal hot mix asphalt concrete and hot mix recycling asphalt concrete. Data Source In recent years, the greenhouse gas inventory of the industry has been promoted gradually at home to coordinate with the international trend. However, the domestic civil construction industry has no public industry database at present, so the study collects data from various types of manufacturers in the product system and compares with the same industry abroad. The categories of the manufacturers that provide data are shown in Table 1. The fuel and power usage carbon emission factor during the carbon emission calculation process adopt the data announced by the Bureau of Energy. During the research period, the national power emission factor is 0.612kg-CO 2 e/ degree, the heavy oil emission factor is 3.11kg- CO 2 /L, and the diesel oil emission factor is 2.61kg- CO 2 /L [5].