Due to global warming, in the construction sector there is aimed for a transition towards the circular economy. The past years, many utility buildings were demolished, consisting of a concrete structure. This results in concrete rubble which is often down- or recycled. For new construction projects, new concrete elements will be produced. However, instead of producing new concrete structural elements, potentially concrete structural elements can be reused. Therefore, this research focuses on the reuse potential of in-situ concrete elements whose can be dismantled from demolition projects of utility buildings. In order to stimulate structural engineers to reuse concrete structural elements in practice, this research presents the Reusability Tool. This tool assesses the reuse potential of in-situ concrete structural elements based on structural safety, environmental impact, and economic impact. Based on an extensive desk research, interviews with experts from the field, and a case study, the processes of three circular strategies are analysed: reusing, upcycling, and downcycling. These processes are made operational in the Reusability Tool. Based on input information about the analysed structural element, the Reusability Tool assesses the element on structural safety, environmental impact, and economic impact. This assessment result in an advised circular strategy for the element: reuse, upcycling, or downcycling. The Reusability Tool is validated by a case study and feedback sessions with structural engineers. The Reusability Tool is a user friendly tool which can be used to assess the reuse potential of in-situ concrete structural elements from utility buildings, and will prevent valuable elements to get lost. The tool can give insight in the reuse potential in an early design stage of a future project, and can form the basis for further investigations.