# Limitations on the Use of Recycled Asphalt Pavement in Structural Concrete
## 3 Quality and Homogeneity of RAP Aggregates
### Minimum Requirements in Italy for RAP Aggregates to Be Used in Concrete
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Essential** & **Clause in EN** & **Property** & **Testing Method** & **Symbol/Category** & **Italian Requirements (a)** & **NOTES (a)** & **Experimental Values** \\
**Characteristics** & **12620** & **Property** & **Testing Method** & **Symbol/Category** & **(UNI NS20-2)** & **NOTES (a)** & **from Literature** \\ \hline \multirow{3}{*}{Durability against freeze-thaw} & 5.7.1 & Freeze-Thaw resistance & EN 1367-1 [91] & F\({}_{\rm ex}\) & For XF classes category \(\leq\) F\({}_{2}\) & - \\  & & Magnesium sulfate & EN 1367-2 [92] & MS\({}_{\rm ex}\) & For XF classes Category \(\leq\) & - \\  & & & & & & \\  & & Freeze-Thaw resistance in the presence of salt & EN 1367-6 [93] & FEC\({}_{\rm ex}\) & Category must be declared & - \\  & & & (NaCl) & & & \\ \hline \multirow{3}{*}{Resistance to polishing/baseline} & Resistance to abrasion from stacked types & EN 1097-9 [94] & AN\({}_{\rm ex}\) & No specific limits & - \\ \cline{1-1} \cline{2-6}  & Durability against alkali-silica reactivity & 5.7.3 & Al alkali-silica reactivity & UNI 8520-2 [95] & No limits for RA & UNI 8520-2 [95] & - \\ \cline{1-1} \cline{2-6}  & & & & & 1 only refers to NA & - \\ \hline \hline \end{tabular}
\end{table} 
Table 4: _Cent._Another important aspect of aggregates is the resistance to fragmentation, determined in terms of the Los Angeles (LA) value, which corresponds to the percentage of the initial mass which has passed the 1.6 mm sieve after degradation in a horizontal drum for a specific number of revolutions (500). A low LA value indicates that the material has a high abrasion resistance. Conversely, a high LA value indicates that the material has a low abrasion resistance [8; 16; 44; 45; 46]. The binding requirement is when the aggregate is destined to be used in C50/60 concrete. In this case, the maximum LA value should be less or equal to LA\({}_{30}\), which means that the resistance to fragmentation expressed with the Los Angeles coefficient shall be LA \(\leq\) 30. When evaluated with EN 1097-2 [77], the range of LA values was shown to be between 24 and 27 [44; 45; 46]. However, the LA value is heavily dependent on the quality of RAP used, especially its origin, which suggests that an appropriate selection is required in order to avoid a weak mechanical performance. Experimental values evaluated in accordance with American standards (ASTM C131 [96]) were also analysed: the Los Angeles abrasion resistance value for coarse RAP was found to be less than 38%, which implies that RAP does not have a uniform hardness [97]. However, it has to be said that testing the resistance to fragmentation with different test method standards [98] can reveal different results, which may be not directly comparable. As regards the study of composition/content in [PERSON] et al. [3], the petrographic analysis was conducted following EN 932-3 [57] and it showed no gypsum, amorphous silica or pyrite content in the RAP aggregate used. The chemical composition was also studied by [PERSON] [3] in terms of sulfate, sulfur and soluble chloride contents according to EN 1744-1 [65] and it was reported that the values were lower than the limits defined by EN 12620. However, the obtained values were not reported in this study, and therefore a direct comparison between the minimum requirements reported in UNI 8520-2 and chemical composition values was not possible. The water absorption of aggregate represents the ability of RAP to absorb water and gives an idea of the strength of aggregate: a high value of water absorption indicates high porosity of the aggregate, which make it unsuitable for concrete, unless it is found to be acceptable based on other tests like strength, hardness and impact [75]. UNI 8520-2 [79] only gives indications on absorption when the exposure class is for freeze/thaw risk, requiring a further examination of freeze and thaw when the value of water absorption is higher than 1%.