Flexural Behaviors of 3D Printed Lightweight Engineered Cementitious Composites (ECC) Slab with Hollow Sections (2023-11)¶

3D concrete printing (3DCP) is a form-free construction method that offers the potential to construct load-efficient structures with unique shapes. However, 3DCP currently lacks a compatible reinforcement method. This paper aims to print self-reinforced lightweight slabs using engineered cementitious composites (ECC). By introducing honeycomb-like (HS) and rectangular hollow sections (RS) into printed ECC slabs, the self-weight of HS and RS slabs is reduced by over 30.5% and 35.7%, respectively, compared to that of a solid slab. The flexural behaviors of the printed slabs were investigated via four-point bending test and finite element modeling. Experimental results show that the printed ECC slabs exhibit typical ductile failure even in the absence of steel reinforcement. The maximum flexural strength-to-mass ratio of HS and RS slabs approaches 0.049 MPa/kg, which almost equals to the value of solid slab. The numerical models were validated using the experimental results. Furthermore, parametric analysis reveals that bond strength higher than 1.5 MPa can achieve a stable flexural behavior for HS slab. The findings lay the groundwork for load-efficient and lightweight structural design by using ECC in 3DCP.