Residual water reutilisation in the process of recycling left-over concrete in concrete manufacturing can be assumed to be state-of-the-art technology in quality-assured concrete production. The objective of the recycling process is to attain closed-loop material circulation. The first stage is to conduct the liquid residual concrete or incidental washing water to a recycling plant, where the bound cement fines are washed out. These reach an agitator basin together with any sand fines with a particle size < 0.2 mm and the excess water (residual water) from the recycling process. The fines are held in suspension there and subsequently recirculated into concrete production.