## 3 Results and Discussion  
### Environmental Results  
Numerical environmental results obtained for the production of 1 ton of NCA in a gravel pit, for the impact categories of the EPD methodology, plus the land use impact category of the ReCiPe methodology in its mid-point results, can be found in Table 2. Furthermore, Figure 2 shows how the processes and materials identified in the LCI contribute in percentage terms to the total impact (0-100%) in each category (value represented in Table 2). Therefore, the substances or processes that have the greatest negative impact can be easily identified and action can be taken in order to improve the environmental sustainability of the process. From all the results shown in Table 2, it can be summarized that the production of 1 ton of NCA from gravel pit means the emission of 4.30 kg CO\({}_{2}\) eq affecting the Global Warming Potential category. This is in addition to consuming 106.06 M] of energy from fossil fuels and a natural water consumption of 12.52 m\({}^{3}\). The following information can be extracted if the results are discussed in detail according to Figure 2. The Water Scarcity category represents natural water consumption, as can be seen by the raw material water accounting for approximately 75.83% of the impact with a value of 15.54 m\({}^{3}\) per ton of NCA. This high water consumption is justified because in the production of natural aggregates, water is essential in the production process and is used during the aggregate washing process, as well as a protective measure to avoid the emission of dust particles on the tracks from the gravel pit site to the aggregate production plant [2]. However, this category of impact is mitigated by a positive impact as the recycling process of this used water reduces the impact by 24.17%, equivalent to not using 3.03 m\({}^{3}\) of natural water per ton of NCA. The next category of impact to be analyzed is that of Fossil Fuel Depletion, where practically 92.53% (98.14 MJ/t) of the total impact is generated by the consumption of diesel fuel, i.e., its production process where diesel is obtained through the refining of oil and in which energy is used. This is in addition to their respective combustion in the AICEs of the machinery used in the gravel pit. The next process that can be considered to contribute to this impact is the internal transport of aggregates 6.79% (7.2 MJ/t), and its justification as before is related to the fact that the tanker trucks use diesel that is combusted in their engines. The transport process has a lower impact in all categories assessed compared to the activities of virgin material extraction and its aggregate production process, etc. [27]. The same result is evident in the research of [PERSON] et al., where the production of 1 t of NAs causes a consumption of 262.53 MJ for the gravel crushing process and 54.85 MJ for the transport process [27]. Further analysis of the use of diesel fuel and its combustion in the extraction of virgin material at the quarry site and its aggregate production process shows that the sum total of these processes has a very significant and even predominant impact on categories affecting air quality--Ozone Depletion with 92.72% (1.27 \(\times\) 10\({}^{-7}\) kg CFC-11 eq), Photochemical Oxidation 97.95% (5.15 \(\times\) 10\({}^{-2}\) kg NMVOC) and Acidification with 96.19% (3.77 \(\times\) 10\({}^{-2}\) kg SO\({}_{2}\) eq). Complementary to these impacts is the internal transport activity with values for the previously identified impact categories of 6.82% (9.34 \(\times\) 10\({}^{-8}\) kg CFC-11 eq), 2.10% (6.59 \(\times\) 10\({}^{-4}\) kg NMVOC),  
Figure 2: Environmental results expressed as a percentage for each impact category assessed for the production of 1 ton of NCA. and 1.26% (8.25 \(\times\) 10\({}^{-4}\) kg SO\({}_{2}\) eq), respectively.