Physico-Chemical Characterization at Early-Age of 3D Printed Mortar Ilhame Harbouz 1(&) , Emmanuel Roziere 1 , Ammar Yahia 2 , and Ahmed Loukili 1 1 Ecole Centrale de Nantes, 1 rue de la Noe, 44321 Nantes, France ilhame.harbouz@ec-nantes.fr 2 Université de Sherbrooke, Sherbrooke, QC J1K 2R1, Canada Abstract. 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 mea- surements 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. Keywords: 3D printing Á Cement-based material Á Rheology Á Elastic properties Á Thixotropy Á Green strength Á Non-destructive test methods Á Structuration kinetics 1 Introduction The author ’s ongoing research is mainly focused on 3D printing as an innovative construction technic to achieve distinctive advantages over conventional construction methods. Higher construction ef ficiency, less intensive labor and waste production, as well as the improvement of architectural freedom to produce geometrically complex elements are the major benefits that can be achieved [1]. The properties at fresh state of 3D printed cement-based materials are crucial for successful printing process. The mixture design of cement-based materials needs, therefore, significant improvements to meet the requirements of 3D printing. Indeed, several rheological requirements, espe- cially structuration kinetics, should be considered to tailor a 3D printable mix design. The required properties involve adequate fluidity to facilitate the extrusion and suf ficient © RILEM 2020 F. P. Bos et al. (Eds.): DC 2020, RILEM Bookseries 28, pp. 272–279, 2020. https://doi.org/10.1007/978-3-030-49916-7_28