Abstract
To comply with recent international trends and initiatives, and in order to help achieve sustainable development, Korea has established a greenhouse gas (GHG) emission reduction target of 37% (851 million tons) of the business as usual (BAU) rate by 2030. Regarding environmentally-oriented standards such as the IGCC (International Green Construction Code), there are also rising demands for the assessment on CO2 emissions during the life cycle in accordance with ISO (International Standardization Organization’s Standard) 14040. At present, precast concrete (PC) engineering-related studies primarily cover structural and construction aspects, including improvement of structural performance in the joint, introduction of pre-stressed concrete and development of half PC. In the manufacture of PC, steam curing is mostly used for the early-strength development of concrete. In steam curing, a large amount of CO2 is produced, causing an environmental problem. Therefore, this study proposes a method to assess CO2 emissions (including absorption) throughout the PC life cycle by using a life cycle assessment (LCA) method. Using the proposed assessment method, CO2 emissions during the life cycle of a precast concrete girder (PCG) were assessed. In addition, CO2 absorption was assessed against a PCG using conventional carbonation and CO2 absorption-related models. As a result, the CO2 emissions throughout the life cycle of the PCG were 1365.6 (kg-CO2/1 PCG). The CO2 emissions during the production of raw materials among the CO2 emissions throughout the life cycle of the PCG were 1390 (kg-CO2/1 PCG), accounting for a high portion to total CO2 emissions (nearly 90%). In contrast, the transportation and manufacture stages were 1% and 10%, respectively, having little effect on total CO2 emissions. Among the use of the PCG, CO2 absorption was mostly decided by the CO2 diffusion coefficient and the amount of CO2 absorption by cement paste. The CO2 absorption by carbonation throughout the service life of the PC was about 11% of the total CO2 emissions, which is about 16% of CO2 emissions from ordinary Portland cement (OPC) concrete.
Highlights
Greenhouse gases (GHGs) are arguably the most prevalent global environmental problem
Carlo et al focused on the analysis of the entire main input inventory data used for assessing the environmental impacts linked to the life cycle of a precast concrete shed: great importance was given to the use of on-site collected specific data which was carefully verified in order to assure its quality and reliability [14]
The CO2 emissions and CO2 absorption capacity by carbonation were assessed for precast concrete girders (PCGs) manufactured by a PC concrete manufacturer (Figure 3) in the Republic of Korea [33,34,35]
Summary
Greenhouse gases (GHGs) are arguably the most prevalent global environmental problem. The building construction industry has played a role in impoverishing the environment; developments have occurred for the sake of improving our quality of life, but at a great cost of impact to the environment [2]. The system boundaries designed to assess CO2 emissions throughout the concrete life cycle were drawn between the following stages: raw material, transportation, manufacture, use. PC engineering is defined as a process of transporting the manufactured concrete member to a construction and civil-engineering site and assembling it properly It is widely used in construction sites, such as in the underground spaces of apartments and stadiums due to its easy process management and great constructability. CO2 absorption was assessed for PCGs, using conventional carbonation and CO2 absorption-related models
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