Comparison between methods for indirect assessment of buildability in fresh 3D printed mortar and concrete

Abstract

This paper presents a comparison between indirect methods for assessing the buildability of 3D printed cementitious materials, including constant rotational velocity (CRV) or constant shear rate (CSR) test using rotational rheometry, unconfined uniaxial compression test (UUCT), a newly proposed confined uniaxial compression test (CUCT), and fast penetration test. The experimental program was conducted on the extruded samples of six printable mortars and two printable concretes with various rheological behavior achieved by the use of different additives and admixtures. Predictions of the material failure and the stability failure in hollow cylindrical structures are provided and compared with the results of the direct printing test. Benefits and disadvantages of the employed test methods are discussed, also taking into consideration a perspective of their use for automated in-situ control of the materials' buildability.