# Recycled Eco-Concretes Containing Fine and/or Coarse Concrete Aggregates. Mechanical Performance
## 1 Introduction
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Country** & \begin{tabular}{c} **Aggregate** \\ **Type** \\ \end{tabular} & **Fraction** & \begin{tabular}{c} **Max.** \\ **Substitution** \\ **(\%)** \\ \end{tabular} & **Concrete Type** & **Strength Class** \\ \hline Australia & RCA (Class 1A) & Coarse & 30 & Structural & C40/50 \\ \hline \multirow{5}{*}{China GB/T-25177 [12]} & RCA—Type I & & 100 & Structural & No limit \\ \cline{2-6}  & RCA—Type II & Coarse & 30 & Structural & C40/50 \\ \cline{2-6}  & RCA—Type III & & 30 & Structural & C25/30 \\ \cline{2-6}  & RCA—Type I & & 100 & Structural & C40/50 \\ \cline{2-6}  & RCA—Type II & Fine & 30 & Structural & C25/30 \\ \cline{2-6}  & RCA—Type III & & 30 & Non structural & - \\ \hline Korea & \multirow{2}{*}{RCA KS-F-2573 [13]} & \multirow{2}{*}{RCA} & Coarse & 30 & Structural & 27 MPa \\ \cline{2-6}  & KSAF-2573 [13] & & Coarse + Fine & 30 & Non structural & 21 MPa \\ \hline \multirow{5}{*}{\begin{tabular}{c} Hong Kong \\ CS-3:2013/HKBD 2009/WBTC-No. \\ 12 [14] \\ \end{tabular} } & \multirow{2}{*}{RCA} & Coarse & 20 & Structural & \begin{tabular}{c} C25/30- \\ C35/45 \\ \end{tabular} \\ \cline{2-6}  & & & 100 & Non structural & \\ \cline{2-6}  & RCA—HQ & Coarse & 100 & Structural & C45/55 \\ \cline{2-6}  & & Fine & 100 & & \\ \cline{2-6}  & \multirow{2}{*}{RCA—MQ JJS-5021 [15]/JS-5022 [16]/ JJS-5023 [17]} & \multirow{2}{*}{RCA—MQ JJS-5023 [17]} & \multirow{2}{*}{RCA—MQ JJS-5023 [18]/JS-5022 [16]/ JJS-5023 [18]/ JJS-5023 [18]/ RCA—MQ JJS-5023 [18]/ RCA—MQ JJS-5023 [18]/ JJS-5023 [18]/ RCA—MQ JJS-5023 [18]/ RCA—MQ JJS-5023 [18]/ JJS-5023 [18]/ RCA—MQ JJS-5023 [18]/ RCA—MQ JJS-5023 [18]/ JJS-5023 [18]/ RCA & Coarse & 50, 30, 20 & Structural & C30/37 \\ \hline \multirow{5}{*}{\begin{tabular}{c} Belyium PTV 406-2003 [18]/NBN B 15-001 [19] \\ \end{tabular} } & \multirow{2}{*}{RCA—Type A} & Coarse & 60 & Structural & C25/30 \\ \cline{2-6}  & RCA 2 & & 15 & & C45/55 \\ \cline{2-6}  & \multirow{2}{*}{RCA 1} & Coarse & 100 & & \\ \cline{2-6}  & RCA 2 & Coarse and fine & 100 & & \\ \hline \multirow{5}{*}{\
\begin{tabular}{c} Denmark \\ DS 2426/DCA No. 34 [22] \\ \end{tabular} } & \multirow{2}{*}{RCA 2} & Coarse & 100 & & \\ \cline{2-6}  & RCA 2 & Coarse and fine & 100 & & \\ \cline{2-6}  & Netherlands & & & & \\ \cline{2-6}  & NEN-5905 [23] & & & & \\ \hline \multirow{5}{*}{
\begin{tabular}{c} Portugal \\ LNEC-E471 [24] \\ \end{tabular} } & \multirow{2}{*}{RCA 1} & Coarse & 25 & Structural & C40/50 \\ \cline{2-6}  & RCA 1 & Coarse & 100 & & \\ \cline{2-6}  & RCA 2 & Coarse & 100 & & \\ \cline{2-6}  & RCA 2 & & 100 & & \\ \hline \end{tabular}
\end{table} 
Table 1: Regulatory framework for the use of recycled aggregates in concrete manufacture. There are numerous works that have studied the use of recycled aggregates from concrete crushing in structural concrete manufacture. [PERSON] [31] statistically analysed a large database with experimental results of concretes that included a coarse fraction of recycled concrete aggregates, reaching the following conclusions: (i) the optimal substitution percentage is below 20%, where the best properties in concrete are obtained; (ii) although strength losses occur as the substitution percentage and the use of homogeneous aggregates increases (as in the case of total substitution), it provides better results as the entire fraction has the same properties; (iii) the strength of concrete with recycled aggregates is affected by an increase in the effective water/cement ratio; and (iv) fracture behaviour is unpredictable due to the notable differences in rigidity within the concrete matrix, on which point further study is required. Several authors also conclude that recycled concrete aggregates can also be used regardless of the fraction and substitution percentage if optimal quality of the new concrete is achieved.