A potential active rheology control approach for 3D printable cement-based materials: Coupling of temperature and viscosity modifiers

Abstract

Recently, the active rheology control for 3D printable cement-based materials (3DPCM) has gained increasing attention due to the challenging rheological requirements during printing. Inspired by the influences of polymers on the temperature sensitivity of rheological properties, here we propose a concept of active rheology control for 3DPCM coupling temperature control with the utilization of viscosity modifiers. Firstly, the rheological properties associated with 3D printing in response to a temperature range from 5 °C to 45 °C were investigated through flow curve, stress growth and small-amplitude oscillatory shear tests. Subsequently, total organic carbon and isothermal calorimetry tests were performed to further analyze the mechanism. Finally, validation 3D printing tests were conducted. Results indicate that increasing temperature improves the efficacy of hydroxypropyl methylcellulose and polycarboxylate ether-based superplasticizer through accelerated dissolution and adsorption, and enhanced chain stretching, thus allowing for an intensified or a suppressed response to temperature in the apparent viscosity, thixotropic area, static yield stress and storage modulus of 3DPCM. Increasing temperature also compensates for the delay in cement hydration due to the addition of polymers. Printing experiments provide preliminary evidence of the feasibility of active rheology control for 3DPCM through coupling between temperature and viscosity modifiers to improve the printability. The thickness ratio and width ratio of top layers to bottom layers of 3DPCM with HPMC were 1.46 and 0.84 when printed at 25 °C, which are 14.1% lower and 58.3% higher compared to that printed at 15 °C.