Shear behavior of 3DPM-NM specimens with different interfacial locking designs

Abstract

Since 3D printed concrete has a promising application in engineering, the combination of 3D printing concrete and other building materials has become a hot research topic.This paper investigates the shear properties of 3DPM-NM specimens which use 3D printed mortar (3DPM) as the precast part and normal mortar(NM) as the cast-in-place part. Four different types of interfacial locking design were analyzed in this paper, including L-shaped, C-shaped, S-shaped and K-shaped. The shear damage law of the specimens was analyzed using digital image correlation (DIC) technology. The results show that L-shaped specimens are basically damaged along the shear surface during the loading process. Most of the initial cracks in the C-shaped, S-shaped and K-shaped specimens appeared along the interfacial bonding surface during the loading process. Then, the cracks in the C, S and K-shaped specimens continued to develop along the interfacial bonding surface or spilt through the specimens directly. The results show the shear properties of the C-shaped specimens are similar to those of L-shaped specimens. And the mechanical properties of S-shaped and K-shaped specimens are better than those of L-shaped specimens which increased by 96% (S-shaped), 78% (K-shaped) respectively. The mean slip is increased by 10% in S-shaped specimens and 28% in K-shaped specimens compared with that of L-shaped specimens. According to the AASHTO GSCB INTERIM-2003 specification, the modified formula for the shear bearing capacity of 3DPM-NM specimens is proposed in this study. The calculated resultsare in good agreement with the test results, which theoretically provide guidance for the application of 3DPM, lay the foundation for its feasibility as a structural body of a building.