Use of waste nano-silica rich sludge from photovoltaic production process in self-compacting mortars (SCM) : Survey on the replacement of cement and common fillers by waste nano-silica rich sludge (from the PV industry) for the production of SCC mixes used by Kijlstra Betonmortel B.V.

This progress report presents the last stages of the project. The activities carried out during the last six months are divided into several parts. First, the effects of adding the designed silica sludge slurries in the hydration kinetics of different binder paste were performed using an isothermal calorimeter. Second, based on the previously obtained results on the self-compacting mortars [12], two self-compacting concretes (SCC) were designed and tested, a reference SCC and another SCC modified by the replacement of CEM I 52.5 R with the silica-sludge (30 % by mass). The fresh and hardened properties of the SCC were determined at 16 hrs. As next, high amounts of stable silica sludge slurry were prepared for testing at a pilot scale. For the pilot scale test, two mixes based on the SCC prepared at laboratory scale were prepared and tested for their fresh and hardened properties at 16 hrs, 7 and 28 days. Finally, one concrete slab was cast using the first SCC mix prepared at the pilot scale. The final results demonstrated the technical viability of the replacement of 30% by mass of CEM I 52.5 R by nSS in the SCC recipe used at Kijlstra betonmortel B.V.