Rheological and hydration behaviour of cement pastes containing porcelain polishing residue and different water-reducing admixtures

The pozzolanic activity and great availability of ceramic wastes (such as porcelain polishing residue - PPR) have increased their usage as supplementary cementitious material. However, studies investigating the effect of water-reducing admixtures on the early-age performance of cement-based materials containing such wastes are still lacking. This work investigated the effect of a lignosulfonate-based plasticizer (PL) and two polycarboxylate-based superplasticizers (SP1 and SP2) on the rheology and hydration kinetics of cement pastes containing PPR and quartz filler. Rheological results show that the volumetric replacement of 20% cement by PPR increased the yield stress, viscosity and thixotropy. PL and SP2 show inferior affinity with PPR, exhibiting increased yield stress, viscosity and thixotropy compared with the reference mix. By contrast, SP1 resulted in rheological properties similar to those of the reference mix and improved performance compared with the quartz filler-containing mix. Calorimetry results indicate that both SPs extended the induction period and increased the main heat flow peak compared with PL. The use of a proper water-reducing admixture can overcome workability losses caused by PPR incorporation, reinforcing the feasibility of using this residue as supplementary cementitious material. (C) 2020 Elsevier Ltd. All rights reserved.