This report describes work performed by RISE within Återhus project funded by the Swedish Innovation Agency Vinnova within Challenges-Driven Innovation program. The project aimed for developing new tools for accelerating the transition to circular construction understood as reusing building parts in new buildings. The key part of that process was identified as quality assurance and tackling the challenges concerning legal regulations, certification processes, determination of material quality by non-destructive and destructive testing, as well as calculation of remaining service-life. The report discussed also the most common deterioration mechanisms affecting service-life based on the pilot cases from the project. The calculation tool included carbonation and chloride ingress as two main mechanisms leading to risk of corrosion. Additionally theoretical relation of environment relative humidity to corrosion rate was embedded in the calculation to give an estimate of the remaining propagation period after corrosion initiation. The calculation tools were applied to estimate the residual service-life of slab elements of four pilot buildings based on empirical data gathered during inventory and condition assessment using both non-destructive methods and laboratory testing. A simple classification of concrete elements was proposed with a clear link to three main factors: remaining calculated service-life, observed cracking and the target environment.