## 3 Materials and Methods
### Life Cycle Inventory
#### 3.3.3 Manufacturing (A3)
For REF1, REF2 and DELTA mortars, scenario B generates an increase in the production of GWP of +26% compared to scenario A; for HP the increase is +22%. Cement production is the process that mostly affects the GWP of mortars, being responsible for more than 63% of the total GWP for all mixtures. The contribution related to benefits of nonoccurrence of landfill disposal is also significant: especially for DELTA mortar, which negatively affects GWP by 34% in scenario A and 27% in scenario B. However, the beneficial contribution of HP mortar is smaller (8% and 7% in A and B scenarios, respectively). The LCA results related to the other examined environmental categories are presented in Supplementary Information SI-1. However, a summary of all impacts differences between mortars, in scenarios A and B, is shown in Table 5 for REF1 and DELTA mortars and in Table 6 for REF2 and HP mortars. From the results reported in the tables, it appears that the environmental performance of DELTA mortar is always better than REF1 mortar, for every impact category and in both scenarios A and B. Albeit with smaller differences, also HP mortar shows a better environmental performance than REF2 mortar, except for ADP-minerals & metals, scenario A, where the performance is comparable (0.07% difference). In general, the performance difference between DELTA and REF1 mortar is more noticeable than that between HP and REF2, due to the total replacement of natural aggregates with recycled materials in DELTA mortar (versus a partial replacement in the HP mixture). \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & & \multicolumn{2}{c}{**REF2-HP Comparison**} & \multicolumn{2}{c}{**Scenario A–B Comparison**} \\ \cline{3-6}  & **A** & **B** & **REF2** & **HP** \\ \hline GWP & kg CO2 eq. & \(-\)8\% & \(-\)11\% & 26\% & 22\% \\ ODP & kg CFC11 eq. & \(-\)3\% & \(-\)13\% & 136\% & 111\% \\ POCP & kg NMVOC eq. & \(-\)3\% & \(-\)10\% & 65\% & 54\% \\ AP & mol H + eq. & \(-\)3\% & \(-\)8\% & 46\% & 37\% \\ EP–freshwater & kg P eq. & \(-\)3\% & \(-\)8\% & 46\% & 37\% \\ EP–marine & kg N eq. & \(-\)174\% & \(-\)11\% & 59\% & 64\% \\ EP–terrestrial & mol N eq. & \(-\)2\% & \(-\)9\% & 59\% & 48\% \\ ADP–minerals \& cells Ste Ste eq. & \(+\)0.07\% & \(-\)2\% & 11\% & 8\% \\ ADP–fossil & MJ & \(-\)3\% & \(-\)9\% & 60\% & 49\% \\ PE-Nre & MJ & \(-\)3\% & \(-\)9\% & 60\% & 49\% \\ PE-Re & MJ & \(-\)11\% & \(-\)11\% & 6\% & 5\% \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Environmental impacts difference between REF2 and HP mortars (in both scenarios A and B) and between scenarios A and B (within each mortar typology). \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & & \multicolumn{2}{c}{**REF1–DELTA Comparison**} & \multicolumn{2}{c}{**Scenario A–B Comparison**} \\ \cline{3-5}  & **A** & **B** & **REF1** & **DELTA** \\ \hline GWP & kg CO2 eq. & \(-\)26\% & \(-\)26\% & 26\% \\ ODP & kg CFC11 eq. & \(-\)18\% & \(-\)22\% & 136\% & 124\% \\ POCP & kg NMVOC eq. & \(-\)13\% & \(-\)18\% & 65\% & 56\% \\ AP & mol H + eq. & \(-\)9\% & \(-\)14\% & 46\% & 38\% \\ EP–freshwater & kg P eq. & \(-\)9\% & \(-\)14\% & 46\% & 38\% \\ EP–marine & kg N eq. & \(-\)523\% & \(-\)338\% & 59\% & 11\% \\ EP–terrestrial & mol N eq. & \(-\)10\% & \(-\)16\% & 59\% & 49\% \\ ADP–minerals \& metals Ste Ste eq. & \(-\)0.50\% & \(-\)3\% & 11\% & 8\% \\ ADP– fossil & MJ & \(-\)11\% & \(-\)16\% & 60\% & 51\% \\ PE-Nre & MJ & \(-\)14\% & \(-\)14\% & 6\% & 5\% \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Environmental impacts difference between REF1 and DELTA mortars (in both scenarios A and B) and between scenarios A and B (within each mortar typology). As better detailed in S1, in scenario A the incidence of cement is the most relevant for almost all the impact categories, and especially for: GWP (more than 80%), POPC (more than 76%), AP (more than 75%), EP-freshwater (more than 85%), EP-terrestrial (more than 79%), and ADP-Mineral & Metals (98%).