## 1 Introduction  
In recent years, various methodologies have been established to stimulate the circular economy and the implementation of green public procurement (GPP). The main objectives of these guidelines are to increase the reuse of materials and reduce the environmental impacts caused by state purchases, helping them to simultaneously achieve environmental and development policy objectives [1; 2; 3]. As the World Road Association (PIARC) [4] has also recently recommended (even without having analyzed the techniques that \"minimize recovery time\"), pavements should also be designed and built to be more resilient, not only taking into account traffic and climate changes but also using \"innovative materials\" and techniques. Therefore, it is necessary to encourage the use of recycled materials and the production of more comprehensive technical guidelines and standards that take circular design into account (including the possibility of maintenance and disassembly, as well as the quality assessment of products before and after reuse/recovery). Thus, for example, using recycled concrete aggregates (RCAs) fits in perfectly with these policies and tendencies. For these reasons, it is crucial to continue developing the study and application of all materials that incorporate such aggregates, and their use must be better regulated/standardized. In this regard, some standardization systems already cover \"nontraditional\" aggregates and their complete characterization (as is the case with ASTM). For example, ASTM D6155-19 (\"_Nontraditional Coarse Aggregates for Asphalt Paving Mixtures_\") [5] specifies that the results obtained in the following test methods should be evaluated: grading (C136/C136M) [6], unit weight (C29/C29M) [7], soundness (C88/C88M) [8], degradation (C131/C131M) [9], expansion (D4792/D4792M) [10], friable particles (C142/C142M) [11], coating (D2489/D2489M) [12], fractured particles (D5821) [13], leaching (EPA SW846 131) [14], and stripping (D4867/D4867M) [15]. In the pursuit of these crucial objectives, a project called \"_CirMat_\" [[[https://cirmat.pt/en_GB](https://cirmat.pt/en_GB)]([https://cirmat.pt/en_GB](https://cirmat.pt/en_GB)) (accessed on 24 December 2023)]. was recently organized and developed for almost three years, leading to several relevant conclusions. This article describes the mechanical and environmental characterization of a \"nontraditional\" asphalt concrete (AC) with a high content of RCAs (resulting from the processing of construction and demolition waste, CDW) suitable for use as a surface course and developed as part of the \"_CirMat_\" project. The use of RCAs has been reported in several works, especially in granular layers [16], but also in asphalt mixtures [17] and concrete, mortars, grouts, and so on (e.g., using recycled concrete fines (mostly non-reactive) as specified in EN 197-6:2023 standard [18]). In fact, these aggregates have already attracted interest for application in different layers and types of mixtures, mainly in bituminous base and binder courses [19], as well as in dense/semi-dense asphalt mixtures [20], in stone mastic asphalt (SMA) [21], and even in porous asphalt (PA) [22]. In the meantime, its use has been extended to a wide variety of production methods, namely, cold asphalt mixes (CMAs) [23], foamed asphalt mixtures (FAMs) [24], and warm mix asphalt (WMA) [25; 26; 27], in addition to \"traditional\" hot mix asphalt (HMA) [28; 29; 30; 31; 32]. However, it was also noted that its use in high percentages of incorporation in mixtures for surface layers has not been shared, with only two references describing laboratory studies [21; 33]. With regard to the technical and environmental characterization of paving materials, several studies have recently been published on asphalt mixtures incorporating RCAs [27; 30; 34; 35], including some reviews that concisely systematize the knowledge at the time [17; 19; 36]. In the \"_CirMat_\" project, the environmental performance of these mixtures was measured through a life cycle assessment (LCA).