Rheology of cement pastes with superplasticizer and nanocellulose crystals

Abstract

The addition of nanocellulose to cement-based materials has gained significant attention in recent years due to its potential to improve concrete performance. However, the effects of nanocellulose on the rheological properties of cementitious systems are not fully understood. This work investigated the use of crystalline nanocellulose (CNC) and its effect on yield stress, plastic viscosity and structuration rate of cement pastes with and without superplasticizer admixtures (SP). Different contents of CNC were added (0.00-0.10 wt%) to pastes without and with SP. Rotational rheometry tests were conducted up to 80 min of hydration. Results showed that CNC addition increased static yield stress and structuration rate both of pastes without SP (only for contents above 0.02 wt% of CNC) and with SP (all CNC contents). These effects were more intense in pastes with SP. Regarding dynamic yield stress, only pastes with SP were affected by CNC addition. In turn, plastic viscosity decreased when CNC was incorporated, both in the presence and absence of SP. These findings suggest that CNC can be useful for applications that require relatively high structuration after the material is cast, while keeping a good pumpability (e.g. 3D printing).