Impact of 3D Printing Direction on Mechanical Performance of Strain-Hardening Cementitious Composite (SHCC)

Automatically adding or even printing steel reinforcements into a 3D-printed concrete structure is antithetical to the design freedom as well as construction ease and efficiency. Strain-Hardening Cementitious Composite (SHCC) is a kind of short random fibre reinforced cementitious composites exhibiting robust tensile strain-hardening and multiple cracking, which has potentials to reduce or even eliminate the need for steel reinforcements in printed concrete structures. Since one of the main disadvantages of 3D-printed structures is the anisotropy, this study aims to evaluate the impact of 3D printing directions on the tensile and compressive performance of self-reinforced SHCC materials. Four series of SHCC specimens with the same mix proportion but different printing patterns (including Parallel, Perpendicular, Cross and Normal Casting) were prepared and tested under uniaxial tension and compression, and the single-crack fibre-bridging constitutive relations were micromechanically modelled to physically support the experimental results. The findings of this study can support the future design and manufacturing of 3D-printed concrete structures using fibre-reinforced materials.