# Life Cycle Carbon Assessment of Mortars with Carbonated and Non-Carbonated Recycled Aggregates
## 5 Conclusions  
Previous works aimed to investigate the CO\({}_{2}\) capture capacity of CDW so that it can advantageously be applied in mortars and concretes as an aggregate. It was concluded that mixed recycled aggregates are able to capture 0.66% of CO\({}_{2}\) per weight of aggregate used. Recycled concrete aggregates, on the other hand, are able to capture between 0.88% and 4.09%. These percentages are interesting considering that mortars and concretes are  
Figure 3: Global warming potential of mortars with carbonated recycled aggregates in comparison with a REF mortar.  
composed of a higher volume of aggregates than binders. Thus, these percentages shall be incremented if a mortar or a concrete element is considered.  
This paper presents a life cycle impact assessment of mortars with carbonated recycled aggregates in comparison with mortars with non-carbonated recycled aggregates and mortars with natural aggregates only. This LCA considers a cradle-to-gate boundary, meaning that it evaluates the environmental impacts associated with the extraction and processing of raw materials, as well as their transport and the product manufacturing process. This LCA was focused on the global warming potential (GWP) environmental impact, meaning that it quantifies the amount of CO2 equivalent sent to the atmosphere for the m3 of powder mortars produced.  
On the one hand, the recycled aggregates in raw materials eliminate the impacts associated with sand extraction, and on the other, they add necessary treatments, namely through crushing and sieving processes which also produce environmental impacts. Considering transportation impact, recycled aggregates have more transportation routes than natural aggregates, since they have to be sent to recycling plants before being sent to mortar factories. Carbonated aggregates, in addition, must come from their recycling plant to a cement plant where they are submitted to flue gases to carbonate. Only after that, these aggregates are sent to mortar plants to be incorporated as aggregates. In mortar production, recycled aggregates are favourable since they have lower bulk densities which reduce the energy used in the process. In this research, it was concluded that even though the recycled aggregates are submitted to treatment processes and to additional trips, the mortars with them present a considerable reduction in GWP in comparison with mortars without recycled aggregates.  
Recycled aggregates, when incorporated in mortars, reduce their CO2 equivalent in amounts of 3.3% and 7.5%, depending on the type and origin of recycled aggregate and proportion of incorporation designed. With carbonation, the CO2 emissions are even lower and between 4.2% and 36.8%, by comparison with the corresponding natural sand mortars. These results indicate that the carbonation of recycled aggregates, followed by their incorporation in mortars, significantly reduces the mortars' CO2 footprint, contributing to the targeted carbon neutrality of the United Nations Sustainable Development Goals.  
Conceptualization, C.B.F., C.M.P. and R.V.; Methodology, C.B.F. and C.M.P.; Formal analysis, C.B.F. and C.M.P.; Investigation, C.B.F., C.M.P., R.I.G. and D.B.; Writing--original draft, C.B.F. and C.M.P.; Writing--review & editing, R.V.; Supervision, R.V. All authors have read and agreed to the published version of the manuscript.  
This research was funded within the research project AL7.1 by c5 Lab (Interface Mission 01/C05-i02/2022.P264). The authors also acknowledge the support of National Laboratory for Civil Engineering (LNEC) through the Program RESUME (n.0803/1102/24171), and the research unit CERIS--Civil Engineering Research and Innovation for Sustainability (UIDB/04378/2020) for the support given to this research.  
Not applicable.  
Data Availability Statement: Data is contained within the article.  
The authors declare no conflict of interest.