## 3 Results and Discussion
### Test Results of the Fiber-Reinforced LPC  
The test results of the physical and mechanical properties of the fiber-reinforced LPCs are shown in Tables 10 and 11, respectively. An appropriate mixture design can balance the porosity/permeability and mechanical properties to meet the structural and hydrological performance requirements of PC. It can be seen from Table 10 that the unit weight of the produced LPC was between 834 and 973 kg/m\({}^{3}\), which was significantly lower than that of ordinary weight PC. As can be seen from Table 10, the void ratio of the LPC was greater than 20%, mainly between 20.9% and 25.9%, which was within the range recommended by ACI 522 [12] to obtain PC with proper permeability. In addition, the permeability coefficient was between 21.8-24.5 mm/s, which met the minimum permeability coefficient (1.4 cm/s) of PC required by ACI 522 [12]. This shows that the prepared matrix had proper viscosity and its dosage was sufficient to stably adhere to the aggregate without clogging the voids of the LPC, as shown in Figure 3.  
Furthermore, in order to identify the relationship between the different physical properties of the LPC specimens, a scatter plot of the test results was drawn, as shown in Figure 4. It can be clearly observed from Figure 4 that both the unit weight and permeability coefficient had a nonlinear relationship with the void ratio of the LPC. Among them, the unit weight decreased with the increase in the void ratio, while the permeability coefficient increased with the increase in the void ratio. However, the goodness of fit between the  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Designation** & **Flow Value (mm)** & **Compressive Strength (MPa)** \\ \hline CM1 & 70.0 & 69.1 \\ CM2 & 97.3 & 87.3 \\ CM3 & 116.7 & 76.5 \\ \hline \hline \end{tabular}
\end{table}
Table 9: The flow value and compressive strength of the matrixes.  
Figure 2: The relationship between the torque and spindle speed.  
void ratio and permeability coefficient was relatively low, which was mainly due to the significant influence of other pore structure properties on the permeability. This result is consistent with the literature [68]. On the other hand, the typical failure pattern observed from the LPC specimens after the compressive strength, flexural strength, and splitting tensile strength testing are shown in Figure 5. Generally, the failure path of ordinary PC is mainly governed by the cement matrix or interfacial transition zone (ITZ). Compared with ordinary PC, because the strength of the lightweight aggregate was inferior to that of general aggregate, the failure path of the LPC specimens mainly propagated through the cement matrix and aggregate rather than the ITZ. Taking the compressive and splitting tensile strength specimens as an example, as shown in Figure 6, the fracture surfaces showed that a large area of lightweight aggregates was split and obvious cracks appeared, indicating that the specimens were destroyed.  
Figure 4: Unit weight and permeability coefficient versus void ratio.  
Figure 5: The typical failure of the LPC specimens: (**a**) compressive strength test, (**b**) flexural strength test, and (**c**) splitting tensile strength test.  
Figure 6: The fracture surface of the LPC specimens: (**a**) compressive strength test and (**b**) splitting tensile strength test.