## 1 Introduction
The authors concluded that the use of RA and recycled cement significantly improved this property, obtaining decreases in the diffusion of chloride ions between 12% and 70%, and between 23% and 29%, respectively. [PERSON] and [PERSON] [10] analysed the influence of the use of recycled cement produced from concrete waste (0%, 10%, 20%, 30% and 50% of the total weight of the binders) on the resistance to the penetration of chloride ions of cementitious composites. The authors concluded that the use of 50% recycled cement increases the permeability to chloride ions by more than 300%. However, the authors found that this increase is reduced to around 200% when the concrete is subjected to accelerated carbonation curing. Some studies have also analysed the carbonation resistance of concrete with recycled cement. [PERSON] [11] evaluated the behaviour of self-consolidating concrete with recycled cement from concrete (0%, 15%, 30% and 45% of the total mass of the binders). The author found that the use of this recycled cement causes a significant increase in the carbonation depth of the concrete (between 2.3 and 6.9 times). [PERSON] et al. [12] also evaluated the carbonation resistance of concrete with coarse RA from CDW (25% and 50% of the total coarse aggregates) and recycled cement (with 25% of ceramic wastes). Regardless of the type of cement, the average carbonation depth was slightly higher in materials with 25% or 50% recycled aggregate than in the reference concrete. The use of this partially recycled cement produced from ceramic waste led to an increase in the carbonation depth at 28 days from 4.2 mm to 5.0 mm (increase of 19%). The present investigation follows previous ones that intended to analyse the mechanical behaviour, water absorption, shrinkage and thermal performance of concrete with RA from CDW and recycled cement [13; 14; 15]. In these previous investigations, the authors observed that the use of GRC enhanced concrete environmental performance. At 10% replacement, it lowered the CO\({}_{2}\) emitted in concrete manufacture by 7.5%, and at 25% GRC by 18.7%, relative to concrete made with ordinary Portland cement (OPC). There are already some studies that address the permeability of concrete with recycled cement (mainly from ceramic wastes) or with RA from CDW. However, no previous study has evaluated the permeability to aggressive agents (chloride ions, carbon dioxide and oxygen) of concrete with simultaneous replacement of the two elements evaluated in this investigation. To fill this scientific and technical knowledge gap, this study analyses the effect of replacing Portland cement with ground recycled cement (GRC), at 10% (R10) or 25% (R25). This assessment was carried out on concrete with 100% NA, 50% NA and 50% mixed recycled aggregates (MRA). This experimental campaign involved the evaluation of the permeability to the aggressive agents of these mixes through the performance of oxygen permeability tests, resistance to the penetration of chloride ions and resistance to carbonation. Finally, the evolution of the carbonation front in these mixes was studied with the increase in the exposure time for mixes in different exposure classes, according to the forecasting model proposed by EHE-08 [16]. This assessment in this type of concrete has not yet been carried out in previous investigations.