Effect of mechanically activated recycled concrete powder on the properties of cement paste

This study investigates the effect of mechanically activated recycled concrete powder (RCP) on Portland cement mixtures with an RCP content of 20 % is investigated. The setting time tests showed that the inclusion of RCP increased the setting time in almost all cases. However, better results were achieved with the mechanically activated RCP than with the RCP raw material additive. In addition, the final setting time was reduced by almost one hour overall (from 380 min to 325 min) when the 3 minute grind was used, which had a similar setting time to Portland cement. The mixtures showed similar behavior in the rheological tests, with the initial shear stress decreasing slightly after the addition of the RCP. Overall, the compressive strength of the RCP-containing mixtures decreased compared to the cement-containing samples. However, a positive effect of milling was observed, as the lowest compressive strength reduction of 29.34 % was achieved by the RCP ground for 3 minutes.