Physico-Chemical Characterization at Early-Age of 3D Printed Mortar (2020-07)¶

The rheology is the key factor that controls the 3D printability of cement-based materials. Indeed, the printed material should satisfy both good workability retention to ensure successful extrusion and a well-adapted green strength to support subsequent layers without collapsing. This requires a tricky control of the physico-chemical structuration kinetics. In the present study, in addition to dynamic rheology, ultrasonic wave propagation test was used to monitor the evolution of the elastic and shear moduli with time. Furthermore, isothermal calorimetry measurements were carried out to quantify the chemical evolutions underlying the early-age behavior of 3D printable cement-based material. A comparative analysis was conducted to correlate rheological measurements with those obtained using non-destructive and calorimetry test methods. Based on the obtained results, a new testing methodology combining the rheological and mechanical properties, as well as isothermal calorimetry measurements is proposed. The proposed method allows a better understanding of the physico-chemical structuration kinetics during the setting process, hence allowing proper optimization of the mixture design from rheological and mechanical points of view.