*3.3. Life Cycle Assessment (LCA)*

According to the results of the technological tests, LCA studies were directed on the environmental impacts associated with obtaining the mortar incorporated with 30% of OSPW and cement CPV type. For the analysis of the environmental impacts associated with the mortar production process, OSPW was considered as an alternative raw material to substitute the use of sand, which allows obtaining an avoided impact with the reduction of the extraction of this input.

The LCA study was compiled considering the geographic limitation of the states of Rio de Janeiro and Espírito Santo, in the Brazilian context, in addition to the chemical composition and morphological characteristics of the sand and OSPW found in the studied region. The study was conducted in a comparative way between the two products: the mortar produced in a conventional way (0% OSPW), and the mortar incorporated with 30% OSPW. For this study, the use of CPV-type cement was also considered.

The mortar production process considered at the system boundary consisted of traditional operations and equipment. Thus, studies that direct efforts to analyze the effects of new technologies are recommended. In addition, the present LCA study is dedicated only to analyzing the environmental impacts caused by the products of interest, recommending future analyses on economic and social impacts.

Figure 12 presents the environmental impact of the conventional mortar production process, without the incorporation of OSPW (the characterized analysis can be seen in Table S1 of the Supplementary Materials). Eighteen impact categories were analyzed at midpoint. In a global analysis, it is possible to realize that the cement and sand inputs significantly contribute to the impact associated with obtaining the mortar, as presented by Sánchez et al. [19]. Cement has an intensive impact on the global warming categories, accounting for about 75% of the CO<sup>2</sup> emissions considered in this production process, and also on the mineral resource scarcity category, corresponding to 91% of the impacts

0 10 20

recorded in this category. Jiménez et al. [43] state that cement is the material with the greatest influence in all categories of impacts considered in their studies, in addition to being the main contributor to emissions to air. *Sustainability* **2022**, *14*, x FOR PEER REVIEW 21 of 26

To highlight the main impacts associated with alternative mortar composed of cement type CPV, 30% of OSPW and sand, the LCA was analyzed (Figure 13). It was possible to identify that the replacement of sand by OSPW contributed to the reduction in the associated impacts in most categories, such as in the categories of land use −5%, freshwater eutrophication −9%, marine eutrophication −6% and global warming −5%. The most significant record of impacts associated with the use of OSPW is in the water con-The sand has its largest impact contribution associated with the water consumption category, with over 77%. In addition, the cement used, identified as packing in the study, has considerable impacts on point categories, such as the land use category, reaching 76% of the relative impact. This can be attributed to the area needed to obtain wood that will supply the pulp industry for the manufacture of cement packages. **Figure 12.** Impact life cycle assessment—mortar with 0% OSPW—CPV. GW SOD IR OFHH FP OFTE TA FE ME TE FEC MEC HCT HNC LU MR FR WC CPV Cement Conveyor belt Electricity Industrial machine Packing, cement Sand

sumption category, totaling 2.3% (the characterized analysis can be seen in Table S2 of the Supplementary Materials). To highlight the main impacts associated with alternative mortar composed of cement type CPV, 30% of OSPW and sand, the LCA was analyzed (Figure 13). It was possible to identify that the replacement of sand by OSPW contributed to the reduction in the associated impacts in most categories, such as in the categories of land use −5%, freshwater eutrophication −9%, marine eutrophication −6% and global warming −5%. The most significant record of impacts associated with the use of OSPW is in the water consumption category, totaling 2.3% (the characterized analysis can be seen in Table S2 of the Supplementary Materials). To highlight the main impacts associated with alternative mortar composed of cement type CPV, 30% of OSPW and sand, the LCA was analyzed (Figure 13). It was possible to identify that the replacement of sand by OSPW contributed to the reduction in the associated impacts in most categories, such as in the categories of land use −5%, freshwater eutrophication −9%, marine eutrophication −6% and global warming −5%. The most significant record of impacts associated with the use of OSPW is in the water consumption category, totaling 2.3% (the characterized analysis can be seen in Table S2 of the Supplementary Materials).

**Figure 13.** Impact life cycle assessment—mortar with 30% OSPW—CPV. **Figure 13.** Impact life cycle assessment—mortar with 30% OSPW—CPV.

main categories of impacts that are intensely affected by the industrial activity of ob-

main categories of impacts that are intensely affected by the industrial activity of ob-

In a comparative way, the processes of obtaining the mortar with cement CPV, and the mortar with cement CPV incorporated with 30% of OSPW were analyzed. The nor-

In a comparative way, the processes of obtaining the mortar with cement CPV, and the mortar with cement CPV incorporated with 30% of OSPW were analyzed. The normalized results show the reduction in global impacts when the mortar undergoes the replacement of sand by OSPW. The normalized scale also allows the identification of the main categories of impacts that are intensely affected by the industrial activity of obtaining the product under study, namely marine ecotoxicity, freshwater ecotoxicity, human carcinogenic toxicity, human non-carcinogenic toxicity and terrestrial ecotoxicity (Figure 14). These categories are allocated into two main areas of protection, those being human health and ecosystem quality, often assessed at the endpoint. posure to toxic substances, especially through ingestion and inhalation. Values referring to acute and chronic toxicological effects provide estimates of the toxicological risk and impacts associated with the mass (kilograms) of a substance emitted to the environment, such as dichlorobenzene, for example. The categories related to ecosystem are related to the harmful, sometimes irreversible, action of substances toxic to the environment. This category can be defined for both water and soil, using chemical emissions to air, water and soil. Its indicator corresponds to the ecotoxicity potential of each emission in relation to the reference substance (for example, triethylene glycol).

taining the product under study, namely marine ecotoxicity, freshwater ecotoxicity, human carcinogenic toxicity, human non-carcinogenic toxicity and terrestrial ecotoxicity (Figure 14). These categories are allocated into two main areas of protection, those being

The categories that estimate human health impacts aim to characterize human ex-

*Sustainability* **2022**, *14*, x FOR PEER REVIEW 22 of 26

human health and ecosystem quality, often assessed at the endpoint.

**Figure 14.** Impact life cycle assessment—normalized result of the comparison between conventional and 30% OSPW mortar. **Figure 14.** Impact life cycle assessment—normalized result of the comparison between conventional and 30% OSPW mortar.

Figure 15 presents the comparison in a characteristic mode between the conventional mortar and the mortar incorporation with OSPW. It is possible to notice the decrease in environmental impacts associated with all categories when the mortar is incorporated with OSPW. According to Rebello et al. [6], the incorporation of OSPW in the elaboration of civil construction materials presented better environmental performance The categories that estimate human health impacts aim to characterize human exposure to toxic substances, especially through ingestion and inhalation. Values referring to acute and chronic toxicological effects provide estimates of the toxicological risk and impacts associated with the mass (kilograms) of a substance emitted to the environment, such as dichlorobenzene, for example.

compared to the use of sand. This can be mainly related to the reuse of an inert residue, which implies the reduction in sand extraction for the composition of this mortar, being an avoided impact. The main reductions occurred in the water consumption and terrestrial ecotoxicity categories, recording reductions of 22% and 20%, respectively. According to Santos et al. [44], the The categories related to ecosystem are related to the harmful, sometimes irreversible, action of substances toxic to the environment. This category can be defined for both water and soil, using chemical emissions to air, water and soil. Its indicator corresponds to the ecotoxicity potential of each emission in relation to the reference substance (for example, triethylene glycol).

incorporation of alternative aggregates in conventional mortars (with high environmental impact) requires less energy for production and transport. This mainly applies to the replacement of natural sand in mortars, which can also benefit the technological performance of the material. In LCA studies oriented to the production of construction materials with incorporation of waste, the geographical distance to obtain the inputs stands out. Indeed, distance Figure 15 presents the comparison in a characteristic mode between the conventional mortar and the mortar incorporation with OSPW. It is possible to notice the decrease in environmental impacts associated with all categories when the mortar is incorporated with OSPW. According to Rebello et al. [6], the incorporation of OSPW in the elaboration of civil construction materials presented better environmental performance compared to the use of sand.

and transport have a direct relationship, that is, great distances can be associated with the increase in the environmental impacts considered [45]. This can be mainly related to the reuse of an inert residue, which implies the reduction in sand extraction for the composition of this mortar, being an avoided impact. The main reductions occurred in the water consumption and terrestrial ecotoxicity categories, recording reductions of 22% and 20%, respectively. According to Santos et al. [44], the incorporation of alternative aggregates in conventional mortars (with high environmental impact) requires less energy for production and transport. This mainly applies to the replacement of natural sand in mortars, which can also benefit the technological performance of the material.

**Figure 15.** Impact life cycle assessment—characterized result of the comparison between conventional and 30% OSPW mortar. **Figure 15.** Impact life cycle assessment—characterized result of the comparison between conventional and 30% OSPW mortar.

The carbon footprints for both evaluated processes were obtained and are shown in Table 15. Thus, it was possible to identify the contribution to the environmental impacts of raw materials in the system, mainly associated with the global warming category. Predominantly, CPV cement presents itself as the main contribution to the carbon foot-In LCA studies oriented to the production of construction materials with incorporationof waste, the geographical distance to obtain the inputs stands out. Indeed, distance and transport have a direct relationship, that is, great distances can be associated with theincrease in the environmental impacts considered [45].

print in both scenarios, being responsible for 75.1% of the CO2 equivalent generated in obtaining the mortar without incorporation of OSPW, and 79.7% of the CO2 equivalent in the mortar with the incorporation of 30% of OSPW. **Table 15.** Carbon footprint. **Inputs CPV 0 W (CO2 eq. %) CPV 30 W (CO2 eq. %)**  CPV Cement 75.1 79.7 The carbon footprints for both evaluated processes were obtained and are shown in Table 15. Thus, it was possible to identify the contribution to the environmental impacts of raw materials in the system, mainly associated with the global warming category. Predominantly, CPV cement presents itself as the main contribution to the carbon footprint in both scenarios, being responsible for 75.1% of the CO<sup>2</sup> equivalent generated in obtaining the mortar without incorporation of OSPW, and 79.7% of the CO<sup>2</sup> equivalent in the mortar with the incorporation of 30% of OSPW.


Sand 19.5 14.5 **Table 15.** Carbon footprint.

#### which was recorded in different mortar compositions incorporated by the orna-**4. Conclusions**

mental stones processing waste (OSPW). • According to the tests in the fresh state, it is possible to conclude that the mortar composed of cement of the CPV type, incorporated with 30% of OSPW, stands out in comparison to the others analyzed, presenting higher density, which implies a ma-• Considering the results found in the squeeze flow test, it can be concluded that the greater the displacement achieved by the material, the better its workability level, which was recorded in different mortar compositions incorporated by the ornamental stones processing waste (OSPW).

greater the displacement achieved by the material, the better its workability level,

terial with lower porosity and good water retention index. The workability of this material also stands out, as well as the rapid release of heat that occurs in this mate-• According to the tests in the fresh state, it is possible to conclude that the mortarcomposed of cement of the CPV type, incorporated with 30% of OSPW, stands out in

rial, which positively influences the nucleation process and rapid hydration.

comparison to the others analyzed, presenting higher density, which implies a material with lower porosity and good water retention index. The workability of this material also stands out, as well as the rapid release of heat that occurs in this material, which positively influences the nucleation process and rapid hydration.


**Supplementary Materials:** The following supporting information can be downloaded at: https: //www.mdpi.com/article/10.3390/su14105904/s1, Table S1: Life Cycle Impact Assessment considering the mortar with 0% of OSPW and cement type CPV; Table S2: Life Cycle Impact Assessment considering the mortar with 30% of OSPW and cement type CPV.

**Author Contributions:** Conceptualization, P.I.M. and G.d.C.X.; methodology, G.d.C.X., C.M.V. and A.R.G.d.A.; software, J.d.O.D. and R.P.R.; validation, C.M.V., S.N.M. and J.A.; formal analysis, G.d.C.X. and R.P.R.; investigation, P.I.M. and G.d.C.X.; resources, G.d.C.X., S.N.M. and C.M.V.; data curation, A.R.G.d.A. and J.A.; writing—original draft preparation, G.d.C.X. and J.d.O.D.; writing—review and editing, R.P.R.; visualization, J.A.; supervision, G.d.C.X.; project administration, C.M.V.; funding acquisition, S.N.M. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by State University of the Northern Fluminense (UENF), partial financed by CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior—Brazil) and provided additional financial CNPq (Coordenação Nacional de Pesquisa) Code 309428/2020-3. The participation of A.R.G.A. was sponsored by FAPERJ through the research fellowships proc. no: E-26/210.150/2019, E-26/211.194/2021, E-26/211.293/2021, and E-26/201.310/2021 and by CNPq through the research fellowship PQ2 307592/2021-9.

**Institutional Review Board Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Acknowledgments:** The authors acknowledge the Brazilian governmental research agencies CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior), CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico), and FAPERJ (Fundação de Amparo à Pesquisa do Estadodo Rio de Janeiro).

**Conflicts of Interest:** The authors declare no conflict of interest.
