Time-Dependent Evolution and Strength Modulation of 3D Printed Concrete Pore-Structure Based on Microbial Remediation (2023-09)¶

The post-hardened pore structure's characteristics and the properties of concrete are strongly connected. This study uses 3D printed concrete (3DPC) as the sample to examine how the porosity, average diameter, and printing parameters affect strength after hardened. In order to accomplish the time-dependent management of the concrete pore structure, pre-embedding microorganisms and employing recycled aggregates as carriers were used which rises concrete strength. According to the experimental findings, the porosity of 3DPC is more directly connected to strength increase, and the variation in average diameters represents the strength of anisotropy. Comparing the microbially repaired samples to the control group, the pore structure revealed a 5.66% reduction in 28 day porosity, a maximum reduction in mean pore size of 49.67 μm, and a smaller dispersed pore size for the same volume. Based on the anisotropy coefficient, a prediction model for the time-dependent strength in 3DPC was put forth, and the computed values were confirmed to be the best fit in the Y-axis with the experimental results. The strength performance in the X-axis of the printed specimens after pore structure repair was greater than that of the cast one, and the anisotropy difference was comparatively less.