Evaluation Analysis of the CO2 Emission and Absorption Life Cycle for Precast Concrete in Korea

Abstract

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 CO 2 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 CO 2 is produced, causing an environmental problem. Therefore, this study proposes a method to assess CO 2 emissions (including absorption) throughout the PC life cycle by using a life cycle assessment (LCA) method. Using the proposed assessment method, CO 2 emissions during the life cycle of a precast concrete girder (PCG) were assessed. In addition, CO 2 absorption was assessed against a PCG using conventional carbonation and CO 2 absorption-related models. As a result, the CO 2 emissions throughout the life cycle of the PCG were 1365.6 (kg-CO 2 /1 PCG). The CO 2 emissions during the production of raw materials among the CO 2 emissions throughout the life cycle of the PCG were 1390 (kg-CO 2 /1 PCG), accounting for a high portion to total CO 2 emissions (nearly 90%). In contrast, the transportation and manufacture stages were 1% and 10%, respectively, having little effect on total CO 2 emissions. Among the use of the PCG, CO 2 absorption was mostly decided by the CO 2 diffusion coefficient and the amount of CO 2 absorption by cement paste. The CO 2 absorption by carbonation throughout the service life of the PC was about 11% of the total CO 2 emissions, which is about 16% of CO 2 emissions from ordinary Portland cement (OPC) concrete.

Discussion on the effectiveness of cement replacement for carbon dioxide (CO2) emission reduction in concrete

“…Considering the carbon emissions resulting from the transportation of raw materials and concrete to the site, the literature has several inventories of CO 2 emissions and energy consumption related to a unit of concrete production . The results found from the previous studies in the literature differ significantly.…”

“…As the world is striving towards increased environmental awareness and sustainable development, the major contributors to CO 2 emissions should be quantified . Carbon dioxide emissions are recognized as a significant aspect inherent to concrete production, as concrete is the most widely used construction material and consumption of concrete is about 1 ton CO 2 per year per each person .…”

“…Building materials are closely related to the energy consumed in the production and manufacturing process of building materials. Many studies carried out on cement, concrete, and other concrete ingredients have noted phases of their life cycles that have significant environmental impacts …”

Commentary on Sequestering Atmospheric CO2 Inorganically: A Solution for Malaysia’s CO2 Emission

“…More importantly, the concept of a sequestration service in the mitigation of climate change is based on the differences in sequestration by the alternative ecosystem or state sequestered or emitted over climatic scales [5,6]. For wastes, from processes and concrete structures, which have already been produced, the sequestration mitigation service then becomes the difference between the uptake of CO 2, over the centennial lifetime of the product or structure [7]. As this happens in any event, additions of these wastes to soils would not result in a net gain or a least a substantially reduced gain in the sequestration services, be it to some unknown extent.…”

Efficiency Gap Caused by the Input Data in Evaluating Energy Efficiency of Low-Income Households’ Energy Retrofit Program

“…The building sector accounted for 23% of the total final energy consumption [2]. The Korean government announced its goals, which is a 2030 mitigation target of a 37% reduction in greenhouse gas (GHG) emissions (315 million tons), compared to the business as usual (BAU) emission of 851 million tons at the Conference of the Parties (COP21) of the United Nations Framework Convention on Climate Change (UNFCCC) [3,4]. The building sector aims to reduce greenhouse gas by 132.7 million tons, which is 32.7% of building BAU (197.2 million tons), by 2030, since Korea's building energy consumption is rapidly increasing and its impact on GHG emission is large compared to other sectors.…”