Influence of the mixing procedure on the fresh state behaviour of recycled mortars

The effect of two different mixing protocols on the fresh-state behaviour of self-compacting mortars with and without recycled sand was compared. For this purpose, the mortar mixes were designed considering three solid volume fractions, while maintaining the water to cement ratio and superplasticiser dosage constant. The results conclude that the inclusion of recycled sand harmfully affects the rheological behaviour of the mortars and this effect can be mitigated using mixing protocols with longer mixing times and delayed admixture addition times. Finally, a rheograph was developed to explain the expectable changes in a conventional mix when recycled sand is incorporated, the solid volume fraction is varied and changes are applied to the mixing procedure.

Automated summary

The study found that the inclusion of recycled sand adversely affects the rheological behavior of mortars, which can be mitigated by longer mixing times and delayed addition of superplasticizer. Furthermore, a rheograph was developed to explain the expected changes in rheological behavior when recycled sand is incorporated, solid volume fraction is varied, and changes are made to the mixing procedure.