## 5 Discussion  
In this study, an LCA was performed to evaluate the environmental impacts of mortars made with recycled composite materials as aggregates (DELTA and HP mortars) including how it compared with reference mortars (REF1 and REF2) entirely composed of natural aggregates and with the same strength performance. The analysis was carried out in three phases, of which the following paragraphs report and discuss the main results obtained. Figure 5: Global Warming Potential (GWP-total) in different scenarios of transport for: (**a**) mortars REF1 and DELTA; (**b**) mortars REF2 and HP. In the first phase, a specific \"local\" mortar factory, which also produces natural aggregates, was considered. The real distances between it and the suppliers of recycled aggregates have been assumed. In addition, the distance between the factory and the construction site (module A4) was set considering two alternative scenarios: 50 km (scenario A) and 500 km (scenario B). For all impact categories, and for both scenarios A and B, DELTA and HP mortars always have better performance results than their reference mortars made with raw materials (respectively REF1 and REF2). These results are in line with those obtained in similar studies [6]. A higher impacts reduction is especially obtained for: EP-marine (up to 523%), GWP (up to 26%), ODP (up to 22%), POCP (up to 18%). The improvements are instead more marginal for other categories, such as: AP, EP-freshwater, PE-Re (up to 14%), ADP-fossil, EP-terrestrial, PE-NRe (up to 16%). For ADP-Mineral & Metals, the performances of all the mixtures are practically the same (variations below 3%), given that, in this category, the impact is mostly related to cement production, and considering that cement is present in all mixtures in the same quantity. In general, the environmental benefits of using aggregates from industrial waste are more evident for DELTA mortar (in comparison with its reference REF1), rather than HP mortar (compared to REF2). This is due to the fact that in the DELTA mixture there is a total replacement of natural aggregates with recycled materials, while only a partial replacement happens in the HP mortar. In addition, the environmental benefits are more evident in scenario B, which requires higher transport distances from mortar factory to construction site and then generally higher impacts. Indeed, B scenarios entails much higher impacts than scenario A, especially for ODP (up to 136%), POCP (up to 65%), and EP-marine (up to 64%). In scenario A, the incidence of cement is the most relevant for almost all the impact categories, while the incidence of transport from mortar factory to construction site becomes very relevant, or even most influential, in B scenarios for some impact categories (for instance ODP). The benefits of nonoccurrence of waste landfill disposal are especially significant for EP-marine, providing a total positive environmental balance. In the second study phase, a stochastic approach is applied to LCA, in order to evaluate the impact of inputs' uncertainty (especially that related to materials transports) on LCA outcome variance, through an SA based on [PERSON]'s method. The probability distributions of aggregates transport distances are set with a data fitting procedure based on real delivery distances in Italy. SA results demonstrate that variances on materials transport distances highly affect the outcome variance: A main effect of 78-94% is obtained for transport of natural aggregate in reference mortars; of 29% for transport of recycled aggregate DELTA; of 17% for HP mortar. Given the high influence of transports variation on LCA outcome, a third study phase was performed, considering several transport scenarios with increasing distances between natural/recycled aggregates industries and mortar factories: 0 km, 100 km, 200 km, 300 km, 400 km and 500 km. As expected, for all the analyzed categories, the environmental impact increased with the increase of the delivery distance of aggregate transports.