Quality control tests of fresh 3D printable cement-based materials

Abstract

Three-dimensional concrete printing (3DCP) has emerged as a promising solution for the modernization of the construction sector. Additionally, design optimization allows for material reduction, promoting sustainable construction. Despite these advancements, there is still no standard for the assessment of the fresh state and quality control of 3DCP. This work discusses the results of quality control tests for fresh 3DCP. Specifically, seven samples with different mix designs were produced and subjected to rotational rheometry, slug tests, flow table tests, and buildability tests (i.e., the height supported prior to collapse). The results showed that the yield stress obtained from rheometry and the slug test did not match but fell within the same order of magnitude. The yield stress values obtained from rheometry were the closest to the gravity-induced stress in the buildability test. Regarding buildability prediction, the slug test exhibited the strongest correlation with the number of layers supported in buildability (R2 = 0.92); rotational rheometry also demonstrated a good correlation with that parameter (R2 = 0.80). In contrast, the results of the flow table test neither correlated with the yield stress obtained from any other tests nor proved efficient in predicting buildability. Finally, the paper presented a discussion on testing and printing challenges.