## 3 Results and Discussion
### Microscopic Pore Structure Analysis  
The pore structures of the damaged test blocks poured under three different environments were observed using an electron microscope, as shown in Figure 11.  
Figure 10: Change in shear characteristics and their ratios of test blocks with curing time under different pouring environments: (**a**) strength; (**b**) internal friction angle and cohesion; (**c**) strength ratio; (**d**) internal friction angle ratio and cohesion ratio.  
From Figure 11a-c, it can be seen that in blocks poured in a dry environment, the number of air voids is relatively low, with most air voids having a diameter of approximately 0.1 mm. The air voids are also more dispersed within the test blocks, resulting in minimal impact on the strength loss of the blocks. This is likely because a small amount of air enters the blocks during pouring, forming air voids. However, during the vibration molding process, large air voids gradually disappear with vibration, and small air voids gradually merge into larger air voids, which then move to the surface of the blocks due to buoyancy. As a result, the surface of the block may experience damage, and the air voids gradually detach from the block matrix [43].  
As shown in Figure 11d-f, when the blocks are poured in a pure water environment, the number of air voids inside the blocks is slightly higher compared to those poured in a dry environment. The diameter of most air voids increases, but no giant air void is formed. Additionally, the distribution of air voids within the test blocks is denser. This may be due to the test blocks being surrounded by pure water during pouring. The increased external pressure and the effect of the buoyancy require more force for air voids to move to the block's surface. Large air voids cannot float and leave the block, resulting in larger and more numerous air voids in blocks poured in pure water, which ultimately leads to a reduction in block strength.  
As illustrated in Figure 11g-i, compared to blocks poured in a pure water environment, those poured in a slurry environment do not show an increase in the number of air voids, but there is a polarized distribution of air void diameters. Specifically, small air voids  
Figure 11: Micro-pore structure of test blocks under different pouring environments: (**a**) compression test specimen in a dry environment; (**b**) tensile test specimen in a dry environment; (**c**) tensile test specimen in a dry environment; (**d**) compression test specimen in a pure water environment; (**e**) tensile test specimen in a pure water environment; (**f**) shear test specimen in a pure water environment; (**g**) compression test specimen in a slurry environment; (**h**) tensile test specimen in a slurry environment; (**i**) shear test specimen in a slurry environment.  
have diameters generally less than 0.1 mm, while large air voids have diameters exceeding 0.5 mm, with some even surpassing 1 mm. This significantly affects the quality of block formation. This may be because, during the pouring process, the slurry enters the blocks along with the mortar, increasing the viscosity of the blocks and thereby reducing their flowability. Consequently, small air voids cannot coalesce into larger air voids that overflow, and reduced flowability makes it difficult to achieve a dense pour, leading to more large voids within the blocks. Additionally, the slurry contains a large number of charged ions, which, during diffusion, transfer from the high-concentration slurry to the lower-concentration test blocks, reacting strongly with the polar water molecules. This enhances the interactions between particles in the solution and increases the surface tension of the cement slurry, preventing large air voids from floating away from the matrix.