# Sustainability Enhancement and Evaluation of a Concrete Dam Using Recycling
## 5 Conclusions  
This paper conducts assessments of the LCA, CFA, and LCC for a concrete dam across construction and decommissioning scenarios. While other studies [16,28] have investigated the environmental impacts and costs of dams, this study focuses on the sustainability of dams through material recycling and dam design considerations. It further examines the impact of integrating recycling practices for demolished concrete and steel on the carbon footprint and LCC results by considering different end-of-life scenarios, including material recovery, reuse, and recycling processes. These scenarios assess the environmental benefits of reducing raw material extraction and landfill use, along with the financial implications of recycling logistics and potential savings from reusing materials. In essence, the evaluation of these stages for the dam can be summarized as follows:  
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2. Cement is the largest contributor to the carbon footprint of concrete due to its energy-intensive production. Aggregates and admixtures contribute smaller but meaningful emissions, while transportation and batching also add to the total footprint. 3. The findings highlight the significant environmental impact of concrete production and fuel usage, which are the primary contributors to carbon emissions in construction of 1 m width of the dam, with total CO\({}_{2}\) eq emissions reaching 355 ton/m. Concrete alone accounts for over 305 ton CO\({}_{2}\) eq/m. The project's non-renewable energy consumption exceeds 5,700,000 MJ/m, largely driven by concrete and fuel. 4. Climate change and human health rank as the top environmental concerns, with concrete consistently emerging as the dominant factor in these categories. These findings reinforce the importance of addressing material production and energy consumption to mitigate environmental impacts, particularly in large-scale construction projects such as dam construction. 5. The total estimated cost for the dam's construction phase is approximately USD 0.195 million, with concrete being the most significant contributor, accounting for USD 0.0959 million. Excavation is the second-largest cost at USD 0.0384 million, followed by oil usage at USD 0.0270 million. The overall cost for the decommissioning of the dam is estimated at around USD 0.138 million. Integrating the recycling of concrete and steel leads to an augmentation in the overall cost of dam demolition. To illustrate, if all the employed steel and concrete are recycled, the total cost for the dam's demolition escalates to USD 0.142 million. Figure 11: The effect of increasing the compressive strength of concrete on carbon footprint per 1 m width of the dam. The carbon footprint resulting from the decommissioning process, excluding recycling, was assessed using CFA and amounted to around 735 ton CO\({}_{2}\) eq/m. The outcomes underscore the considerable influence of material recycling on the carbon footprint, demonstrating a notable 95% reduction in greenhouse gas emissions. Recycling concrete as RCA not only reduces waste and conserves natural resources, but also significantly lowers the carbon footprint by decreasing the demand for virgin aggregate extraction. Recycled steel, similarly, can be repurposed in various construction applications, promoting a circular economy approach. These practices contribute to environmental and economic benefits by minimizing landfill usage, reducing greenhouse gas emissions, and aligning with sustainable development goals. * While lower compressive strength requires more concrete, its total carbon footprint remains lower due to its reduced cement content. Conversely, increasing compressive strength reduces concrete volume, but significantly raises carbon emissions, as cement consumption is the primary contributor to greenhouse gas emissions. While this study provides valuable insights into the environmental and economic impacts of recycling practices in the context of dam construction and decommissioning, there are some limitations that should be acknowledged.