## 5 Conclusions  
This study systematically investigates the influence of flowability on the mechanical properties of 3 DPC through combined experimental and theoretical analyses, with particular emphasis on evaluating and explaining anisotropic behavior under different flowabilities. The main findings are summarized as follows:  
1. All 3 DPC specimens exhibited lower compressive, flexural, and splitting tensile strengths compared to cast concrete, along with significant anisotropy: compressive strength (\(X>Y>Z\)), flexural strength (\(Y\approx Z>X2>X1\)), and splitting tensile strength (\(C>T\)). With increasing flowability, reduced porosity and enhanced interfacial bonding improved the compressive strength in all directions and flexural strength in the Y/Z directions, approaching cast concrete levels. However, the flexural strength in the X1/X2 directions and interfacial splitting tensile strength remained substantially lower due to interfacial weaknesses.
2. The anisotropy coefficient \(I_{\text{a}}\) decreased significantly with increasing flowability by 66.7% for compressive strength and 66.8% for flexural strength. Notably, flexural strength demonstrated 3.5-10 times greater anisotropy than compressive strength, reflecting its higher sensitivity to interfacial defects.
3. The aspect ratio of ellipsoidal pores significantly affects the compressive performance of 3 DPC, as quantified through [PERSON]'s fracture theory and stress intensity factor calculations. Flatter pores induce greater stress concentration and lower critical fracture stress, with \(X\) direction specimens exhibiting the most elongated pore geometries and consequently the highest compressive strength, followed by \(Y\) direction and then \(Z\) direction specimens. Notably, increased flowability promotes the transformation of elliptical pores toward more spherical morphologies with reduced flattening, thereby progressively mitigating the anisotropy in compressive performance.  
Conceptualization, X.S. ([PERSON]), H.W., and X.S. ([PERSON]); Data curation, Q.X.; Formal analysis, X.S. ([PERSON]); Investigation, X.S. ([PERSON]); Methodology, X.S. ([PERSON]); Resources, Q.X., H.W. and F.X.; Software, Q.X., H.W. and F.X.; Supervision, H.W. and X.S. ([PERSON]); Validation, X.S. ([PERSON]) and H.W.; Visualization, X.S. ([PERSON]); Writing--original draft, X.S. ([PERSON]); Writing--review and editing, H.W. All authors have read and agreed to the published version of the manuscript.  
The authors are grateful for the sustained support from the National Science Foundation of China (52279141, 52478284), the R&D Program of Zhejiang Province (2023C01154, 2022C04005, 2021C01022), the Shanxi-Zheda Institute of New Materials and Chemical Engineering (2022 SZ-TD016), and the Centre for Balance Architecture, Zhejiang University.  
Not applicable.  
The data that support the findings of this study are available from the corresponding author upon reasonable request.  
Author [PERSON] was employed by SIPPR Engineering Group Co., Ltd. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.