## 2 State-of-Art Review
### The Effect of Varying RFA Incorporation Ratio on Environmental Impact of Concrete
#### 2.3.2 Life Cycle Assessment of RFA in Concrete
\begin{table}
\begin{tabular}{c c c c} \hline
**LCA Boundaries** & **Life Cycle Stages** & & **Life Cycle Stage** \\ \hline \multirow{4}{*}{Cradle to gate} & & A1 & Raw material extraction and processing, processing of secondary material input \\  & Product stage (A1–A3) & & Transport to the manufacturer \\  & & A3 & Manufacturing \\ \hline \multirow{4}{*}{Gate to grave} & Construction process stage (A4–A5) & A4 & Transport to the building site \\  & & A5 & Installation into the building \\ \cline{2-3}  & Use stage—information modules related to the building fabric (B1–B5) & B1 & Use or application of the installed \\  & & B2 & Maintenance \\  & & B3 & Repair \\ \cline{2-3}  & Use stage—information modules related to the operation of the building (B4–B5) & B4 & Operational energy use \\ \cline{2-3}  & & C1 & De-construction, demolition \\  & End-of-life stage (C1–C4) & C2 & Transport to waste processing \\  & & C3 & Waste processing for reuse, recovery and/or recycling (3R) \\  & & C4 & Disposal \\ \hline \end{tabular}
\end{table} 
Table 2: Life cycle assessment (LCA) system boundary. The EI of producing aggregates could be attributed to two main processes; the energy of extracting natural aggregates versus recycling CDW in addition to the transportation to the concrete batch plant. Although the EI assessment data vary widely, there is a unanimous agreement in the references that the EI of recycled aggregates in concrete is proportional to the transportation distances whether a mobile or a normal stationary plant was used (since the distance of transporting CDW would still be the same). [PERSON]' et al. [18] compared the EI of two types of concrete mixes, one using NA and the other using RA, in the Serbian context. The study was based on two transportation scenarios: the first had the concrete batch plant only 15 km away from the recycling plant for RA, while the second considered it as 100 km. The study concluded that the EI of NA and RAC are mostly dependent on travel-distances and transport-type of aggregates between construction sites and recycling plants. Moreover, when transport distances of RA are smaller than that of NA, the EI of the resulting RAC is less than that of NAC even if the former had 3% extra cement in the mix [18]. It is known that the transportation distance changes between the supplier of raw material and the concrete plant based on the region considered. Therefore, a sensitive analysis is recommended before considering the transportation scenario. For example, the method developed by study of [PERSON] et al. [105] can be used to obtain a sensitive analysis. According to ELCD core database V3.0, two main types of lorries (medium sized lorry transport, low impact, maximum capacity of 17.3 tonnes; articulated lorry transport: high impact, maximum capacity of 27 tonnes) are used to transport raw materials to concrete plant (Table 4). \begin{table}
\begin{tabular}{l c c c c c c c c} \hline \hline \multirow{2}{*}{**Source**} & \multirow{2}{*}{**County**} & \multirow{2}{*}{**ADP**} & **GWP** & **ODP** & **POCP** & **AP** & **EP** & **Pe-NeRe** \\ \cline{3-8}  & & & **kg** & **5b** & **5c** & **5d** & **5e** & **5e** & **5e** & **5e** \\ \hline \hline \multirow{8}{*}{Braga [102]} & \multirow{8}{*}{Portugal} & \(3.37\times 10^{-10}\) & \(9.87\times 10^{-3}\) & \(1.71\times 10^{-11}\) & \(2.80\times 10^{-6}\) & \(4.58\times 10^{-5}\) & \(1.08\times 10^{-5}\) & \(1.35\times 10^{-1}\) \\  & & \(1.24\times 10^{-9}\) & \(2.79\times 10^{-2}\) & \(2.26\times 10^{-10}\) & \(9.06\times 10^{-6}\) & \(1.59\times 10^{-4}\) & \(3.54\times 10^{-5}\) & \(3.92\times 10^{-1}\) \\  & & \(1.09\times 10^{-9}\) & \(2.44\times 10^{-2}\) & \(2.43\times 10^{-10}\) & \(7.83\times 10^{-6}\) & \(1.44\times 10^{-4}\) & \(3.18\times 10^{-5}\) & \(3.44\times 10^{-1}\) \\  & & \(1.39\times 10^{-9}\) & \(3.14\times 10^{-2}\) & \(2.09\times 10^{-10}\) & \(1.03\times 10^{-5}\) & \(1.75\times 10^{-4}\) & \(3.90\times 10^{-5}\) & \(4.41\times 10^{-1}\) \\ \hline \multirow{2}{*}{[PERSON] et al.