Effect of polyacrylamide on the workability and interlayer interface properties of 3D printed cementitious materials

Weak interlayer interface is a major drawback of three-dimensional (3D) printed cemen-titious materials technology. In this paper, the effect of anionic polyacrylamide (APAM) with different dosages on the workability, interlayer interface properties (i.e., interlayer durability, shear bond strength) and interface microstructure of 3D printed cement mortar were studied. The relationship between the workability regulated by APAM and the interlayer interface properties was analyzed. The results showed that the interlayer interface properties of printed artifacts had a good correlation with the workability of fresh cement pastes. With the increase of APAM content, the plastic viscosity and structural build-up rate of cement paste improved. Meanwhile, the interface microstructure defects increased, and the porosity became higher, hence resulting in the decline of the interlayer durability and shear bond strength. In addition, the introduction of APAM can improve the cohesiveness and layer stacking performance of 3D printed cement mortar.(c) 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).