Development of 3D printable engineered cementitious composites with ultra-high tensile ductility for digital construction

The current 3D concrete printing (3DCP) technology is limited by the reinforcing methods. Conventional steel reinforcement is hard to be incorporated in the 3DCP process. To overcome this limitation, this study aims to develop 3D-printable engineered cementitious composites (ECCs) exhibiting ultra-high tensile strain capacity of more than 8%, which can be used for digital construction of 'self-reinforced' concrete structures, reducing the reliance on the conventional steel reinforcement. Different volume fractions of polyethylene fibers (1%, 1.5% and 2%) were used to reinforce the ECC matrix. The fresh properties (including the workability, rheological properties and buildability) and the hardened properties (including the compressive and flexural strengths, and the uniaxial tensile performance), along with the microstructure of the developed 3D printable ECCs were experimentally investigated. Conventionally mold-cast ECCs were also prepared and tested for comparison purposes. The results showed that the developed 3D printable PE-ECCs exhibited strong strain-hardening behavior with the tensile strength and tensile strain capacity of up to 5.7 MPa and 11.4%, respectively. In addition, the results showed that the 3D printed PE-ECCs exhibited superior tensile performance to the conventionally mold-cast PE-ECC counterparts. This finding is in good agreement with the results of the microstructural analysis. (C) 2019 The Authors. Published by Elsevier Ltd.