Mechanical Properties of Hardened 3D Printed Concretes and Mortars—Development of a Consistent Experimental Characterization Strategy

Abstract

Today, it is already foreseeable that additive manufacturing of mortar and concrete has groundbreaking potential and will revolutionize or at least fundamentally change the way we build. In recent years, 3D concrete printing (3DCP) with extrusion-based deposition methods has been pushed forward by a growing research community. Albeit being regarded one of the most promising innovations in construction industry, a consistent characterization methodology for assessing the constitutive behavior of 3D printed, hardened cementitious materials is missing, so far, which hinders its widespread use in engineering practice. The major objective of this paper is to fill this gap by developing a new experimental framework that can thoroughly describe the mechanical properties of 3D printed cementitious materials. Based on both a review of state-of-the-art test setups and a comprehensive experimental campaign, the present paper proposes a set of easy-to-use experimental methods that allow us to assess flexural, tensile, shear and compressive strength as well as fracture energy of 3D printed concretes and mortars in a reliable and reproducible manner. The experimental results revealed anisotropic material behavior for flexural, tensile, shear and compressive loading. Furthermore, they confirm that interval time (time gap between deposition of subsequent layers) has a crucial effect on investigated material properties leading to a severe reduction in strength and fracture energy for longer interval times.

Mechanical properties, durability performance and interlayer adhesion of 3DPC mixtures: A state‐of‐the‐art review

“…While it was understood that the perpendicular and parallel directions were similar at a rate of 33%, it was understood that the loads applied in the perpendicular and lateral directions at a rate of 33% gave similar strength. As a result, as stated by Bong et al, 56 and Meurer et al, 60 it was observed that parallel and lateral loadings had the highest similar strength compared to other combinations.…”

Comparison of Properties of 3D-Printed Mortar in Air vs. Underwater

“…Two mixings and two 3D printing tests were carried out separately in the same order. This is because the mechanical properties of 3DCP can be influenced by the age of the fresh mortar mixture [ 19 ]. After mixing each mortar, the slump flow test of ASTM C1437 [ 23 ] was performed immediately after mixing and at the start of 3D printing to measure the consistency of the mortar mixture.…”

“…However, the performance of hardened concrete varies depending on the method used to make the test specimen, test method and condition, specimen size, etc. [ 19 ]. Furthermore, there is still no standard for evaluating and judging the material requirements and characteristics.…”

Effects of Nozzle Details on Print Quality and Hardened Properties of Underwater 3D Printed Concrete

“…Mortar mixes based on the mixture proportions in Table 3 were used and printed using the 3DCP system similarly and in the same order in all six types of print tests. This reduced the change in the mechanical properties of 3DCP by the age of the mix material as much as possible [31]. After mixing each mortar, a slump-flow test according to ASTM C1437 was performed twice using the mortar immediately after the end of mixing and the first printed mortar to measure consistency [32].…”