# 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
From the analysis conducted on RAP aggregates in different studies, it was shown that the lowest value of water absorption for RAP is 1.51% [6] when determined through the Indian IS standard method, while with American ASTM method the value falls between 1.9 and 0.08% [8; 23]. When using the European method of testing, water absorption presents an even higher value, which is about 2.5% [3]. Specific gravity and water absorption can be found in the same list of essential characteristics of EN 12620 [58] and are both tested with European method 1097-6 [82]. This suggests that the European testing method might be more conservative than the other international testing methods. Crossing all the information on aggregates for concrete that can be found in EN 12620 [58] and the minimum requirements for Italian standards described in UNI 8520-1/2 [52; 53], that are enforced by the Italian law (NTC 2018 [70]), many characteristics are not fully covered by clear indications when it comes to recycled aggregates, even more so for a bituminous aggregate. When a product is not covered or not fully covered by a harmonised standard, i.e., the performance in relation to its essential characteristics cannot be entirely assessed according to an existing harmonised standard, a possible solution for its qualification could be the drafting of a European Assessment Document (EAD). This document allows the CE marking of the product on the basis of a European Technical Assessment (ETA, see Section 3.2). Article 19 of CPR establishes the cases in which this can occur:  
* absence of harmonised standard: the product does not fall within the scope of any existing harmonised standard;assessment method not adequate: for at least one of the essential characteristics of the product, the assessment method provided for the harmonised standard is not appropriate;
* absence of assessment method: the harmonised standard does not provide for any assessment method for at least one of the essential characteristics of the product. For example, as mentioned previously in Section 3.2, the testing method for the evaluation of crushing resistance does not appear to be suitable for RAP aggregates, which therefore need to be studied in a deeper way in terms of essential characteristics and their assessment method. A specifically developed EAD could therefore indicate the cited characteristic and define a more adequate method for its assessment. In this way, a manufacturer can CE-mark its product and commercialize it in the European market. In Italy, the qualification is mandatory for structural products and materials. As a matter of fact, according to Chapter 11 of NTC 2018 [70], structural products and materials must be qualified under the responsibility of manufacturers and three different situations can occur: (i) materials and products that, for the specific intended uses, fall in the scope of harmonised standards so that the CE marking is mandatory; (ii) materials and products whose qualifications can follow the procedures indicated in the standards itself (i.e., steel rebars or concrete, to cite some); (iii) materials and products which do not fall in the previous cases, and for which the manufacturer must CE-mark on the basis of the relative ETA or, equivalently, has to obtain a Certificate of Technical Assessment (CVT in Italian), the latter issued by the President of the Superior Council of Public Works, on the basis of specifically developed guidelines. The development of an EAD could therefore be a possible way for material qualification if the use of RAP is foreseen for structural elements.