In connection with the construction industry´s carbon dioxide emissions and the constantly increasing demands for sustainability, the reuse of materials becomes an important part of the transition to a circular economy. This study was conducted in collaboration with NCC and examines the environmental and economic aspects of using recycled concrete as aggregate in new concrete. The aim is to compare the climate and cost impact of producing virgin ballast and recycled ballast from a life cycle perspective for a quarry in Kungälv.
To achieve the goal and answer the research question, this study has applied a life cycle analysis (LCA) and a life cycle cost analysis (LCC) in accordance with the established standards SS-EN ISO 14040 and SS-EN ISO 14044. The system boundary was set to “cradle to gate,” focusing on the climate impact and costs from raw material procurement to aggregate production. The data collection included both primary data from NCC in the form of interview studies and field visits, while secondary data was gathered from Environmental Product Declarations (EPD) and established sources as Boverket.
The results showed that the recycled ballast had a lower climate impact (GWP) than the virgin ballast. The GWP of the virgin ballast was 2,49 kgCO2e/ton, while the recycled ballast was 1,88 kgCO2e/ton. Similar results were observed for the costs, with the virgin ballast showing a cost of 19,17 SEK/ton compared to the recycled ballast, where the cost was 8.55 SEK/ton. The results for both costs and climate impact are reported per ton produced material.
The analysis showed that using recycled concrete contributes positively to both climate and economic sustainability. As the blasting moment was not considered, this resulted in a reduced GWP and a lower price for the recycled ballast. However, it was found that transport logistics are crucial for achieving significant climate and cost benefits.
Transport distances are significant for reducing both climate and cost impact, which is clearly evident in both LCA and LCC results. However, the economic analysis in this study is limited to only direct energy costs, such as electricity and diesel in the crushing process as well as transportations. Costs such as maintenance, personnel costs, et cetera, are not considered in this study. This means that the costs analysis is not complete, but despite this, the included energy costs are deemed sufficient to represent the main cost impact of the production process.