# Analysis of Life Cycle Environmental Impact of Recycled Aggregate
## 4 Comparison of Life Cycle Impact Assessment
### Comparison of Environmental Impact by Aggregate Type  
As shown in Table 5, the environmental impact of recycled aggregate was compared with that of natural aggregate and artificial light-weight aggregate, slag aggregate. According to Figure 3, the environmental impact of recycled aggregate was found to be up to twice as high as that of natural aggregate. Compared to natural aggregate, the global warming potential (GWP) was approximately 106% (dry) and 166% (wet) higher, AP was 48% (dry) and 109% (wet) higher, EP was 48% (dry) and 72% (wet) higher, and ODP was 53% (dry) and 90% (wet) higher for recycled aggregate. The manufacturing process for natural aggregate consumes very little energy because it involves simple processes, such as collection, transportation, and (minimal) processing. Figure 3: Environmental impact comparison by aggregate. (**a**) GWP: Global Warming Potential; (**b**) POCP: Photochemical Ozone Creation Potential; (**c**) AP: Acidification Potential; (**d**) EP: Eutrophication Potential; (**e**) ODP: Ozone Depletion Potential; (**f**) ADP: Abiotic Depletion Potential \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Division** & \multicolumn{2}{c}{**GWP**} & **AP** & **EP** & **ODP** & **POCP** & **ADP** \\  & **(qg-CO\({}_{\text{mg}}\)/m)** & **(qg-SO\({}_{\text{mg}}\)/m)** & **(qg-PO\({}_{4}\)\({}^{-}\)\({}_{\text{mg}}\)/m)** & **(qg-C\({}_{11}\)\({}_{\text{mg}}\)/m)** & **(qg-C\({}_{5}\)H\({}_{\text{mg}}\)/m)** & **(qg-Antimony\({}_{\text{mg}}\)/m)** \\ \hline Recycled & Dry & \(2.94\times 10^{-2}\) & \(2.93\times 10^{-5}\) & \(5.44\times 10^{-6}\) & \(4.68\times 10^{-10}\) & \(1.25\times 10^{-5}\) & \(1.60\times 10^{-5}\) \\ aggregate & Wet & \(3.81\times 10^{-2}\) & \(4.13\times 10^{-5}\) & \(6.33\times 10^{-6}\) & \(5.80\times 10^{-10}\) & \(1.53\times 10^{-5}\) & \(2.10\times 10^{-5}\) \\ \hline Artificial & \multirow{2}{*}{\
\begin{tabular}{c} Lightweight \\ aggregate \\ \end{tabular} } & \(5.16\times 10^{-2}\) & \(1.73\times 10^{-4}\) & \(2.80\times 10^{-5}\) & \(4.01\times 10^{-9}\) & \(5.28\times 10^{-5}\) & \(1.94\times 10^{-4}\) \\ \hline Slag aggregate & \(2.26\times 10^{-2}\) & \(1.61\times 10^{-4}\) & \(1.61\times 10^{-4}\) & \(6.49\times 10^{-9}\) & \(2.43\times 10^{-5}\) & \(9.08\times 10^{-5}\) \\ \hline Natural aggregate & \multirow{2}{*}{
\begin{tabular}{c} \(1.43\times 10^{-2}\) \\ \end{tabular} } & \(1.98\times 10^{-5}\) & \(3.67\times 10^{-6}\) & \(3.06\times 10^{-10}\) & \(1.41\times 10^{-5}\) & \(3.82\times 10^{-4}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Environmental impact comparison by aggregate type. Recycled aggregate, on the other hand, requires a lot of energy for physical and chemical processes, such as crushing, sorting, transportation, processing, and particle adjustment. However, the abiotic depletion potential (ADP), an important environmental impact measure, was found to be approximately 20 times higher for natural aggregate than for recycled aggregate. This is because the recycled aggregate is simply recycled construction waste, but natural aggregate depletes natural resources. Among environmental impacts emitted during recycled aggregate production GWP was 43% (dry) and 26% (wet) lower than for artificial light-weight aggregate, but was 30% (dry) and 69% (wet) greater than for slag aggregate. This is because the amount of energy used, such as electricity, LNG (liquid natural gas), and coal in the mixing, molding, and plasticity processes, during artificial light-weight aggregate production was higher than the amount of energy used by recycled aggregate. This was due to the high emissions of CO\({}_{2}\), CH\({}_{4}\), and N\({}_{2}\)O, which are the main compounds impacting GWP. At the same time, the amount of energy used in the differentiation and crushing processes during recycled aggregate production was higher than the amount of energy used by slag aggregate.