Early age fracture performance of 3D printable fiber reinforced cementitious composites

The emerging digital manufacturing technologies, such as concrete 3D printing, require to pay specific attention to the “very early” and “early” performances of the employed cement-based materials, besides the “conventional” hardened state mechanical properties which are required to assess the structural serviceability and ultimate limit states of the intended applications. Indeed, it’s clear that throughout the printing process, the development of the mechanical performances, from the very early stages, can significantly affect the structural build-up and discriminate about the successful accomplishment of the structural performance of the printed object. In this context, the present paper focuses on the early stage properties of a 3D printable fiber reinforced cementitious composite to be used in layered extrusion process. In particular, the development of the stress – strain constitutive behaviour under tensile and shear load conditions has been investigated as a function of the time. In a quality control framework, the development of tensile and shear fracture properties of the investigated materials, in the considered production time frame, is fundamental to discriminate about the printability of the mix, with reference not only to the quality of the finishing, but also to the spped of the printing process.