Investigation on the microstructure of a 3D-printed mortar through a novel leaching-subsidiary tomography

The microstructure of a 3D-printed mortar was investigated in present study. To enhance the density contrast between sand and cementitious slurry, a novel leaching strategy was used as an auxiliary method, based on which the spatial dispersion of sands in 3D-printed mortar was rendered. Meanwhile, to alleviate the problem of CT's limited resolution, X-ray attenuation method (XRAM) was introduced in this study to investigate the spatial distribution of local porosity in 3D-printed mortar. Besides, focusing on single filaments, the upper part of the filaments presented lower sand rate and higher porosity than the lower part, and the difference between the filaments located near the top of 3D-printed mortar was more significant. Finally, based on the sliding method, the interlayer width, average porosity and average sand ratio of 3D-printed mortar were estimated as 640 mu m, 21.9% and 43.1%, respectively. The research results would deepen the understanding of 3D-printed concrete.