## 3 Results and Analysis
### Flexural Strength  
The failure load of the RAIW specimens at different replacement levels was obtained, and the flexural strength of the RAIW was calculated with standards GB/T 50081-2002 [26]. Due to using 100 \(\times\) 100 \(\times\) 400 (mm\({}^{3}\)) non-standard specimens made by the RAIW, the nominal flexural strength was multiplied by a conversion factor of 0.85, in accordance with the relevant Chinese standard [26].  
Details are shown in Table 5. The flexural strength of each specimen measured can be observed. Table 7 gives the analysis of the range and variance data of specimens, from which the primary and secondary impact factors on the flexural strength and their significance can be obtained. The results indicate that among the test factor levels, the water-cement ratio is the major factor that affects the flexural strength, (with the an increase in the water-cement ratio from B\({}_{2}\) to B\({}_{4}\), the flexural strength decreased by 47.76%), followed by the mixed amounts of aggregate cement and lime powder. However, other two factors showed a tendency to fluctuate. Thus, there no significant effects from the regenerated brick granule volume and the replacement rate were observed, indicating their impacts on the compressive strength. Therefore, it can be considered that strict control of the water-cement ratio is important for the mechanical properties of RAIW.  
The intuitive analysis curve of the factors impacting the flexural strength can be observed in Figure 5, from which similar tendencies can be observed for the flexural strength and the compressive strength of RAIW. With increases in the water-cement ratio, aggregate-cement ratio and the lime powder content, the mechanical properties showed a declining trend, and the order of influencing factors was revealed as the following: the water-cement ratio, the aggregate-cement ratio, lime powder, the aggregate replacement rate and the brick granule content in the aggregate.  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Factor**} & \multicolumn{4}{c}{**Level**} & \multicolumn{4}{c}{**Results**} \\ \cline{2-13}  & **1** & **2** & **3** & **4** & **\(r\)** & **Df** & **F** & **F\({}_{\mathbf{0.1}}\)** & **F\({}_{\mathbf{0.05}}\)** & **F\({}_{\mathbf{0.01}}\)** & _Sig._ \\ \hline A & 5.300 & 4.800 & 3.525 & 5.000 & 1.775 & 3 & 0.792 & 2.490 & 3.290 & 5.420 & - \\ B & 4.525 & 6.725 & 4.250 & 3.125 & 3.600 & 3 & 3.294 & 2.490 & 3.290 & 5.420 & * \\ C & 6.825 & 4.850 & 3.700 & 3.250 & 3.575 & 3 & 2.938 & 2.490 & 3.290 & 5.420 & \# \\ D & 6.600 & 4.475 & 3.600 & 3.950 & 3.000 & 3 & 2.342 & 2.490 & 3.290 & 5.420 & - \\ E & 5.475 & 4.975 & 3.925 & 4.250 & 1.550 & 3 & 0.636 & 2.490 & 3.290 & 5.420 & - \\ \hline \hline \end{tabular} Symbol \"*\" represents significant impact, symbol \"#\" represents significant secondary impact, symbol “-” represents significant. The same symbols are used below.  
\end{table}
Table 6: Analysis of the factors influencing the compressive strength.  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Factor**} & \multicolumn{4}{c}{**Level**} & \multicolumn{4}{c}{**Results**} \\ \cline{2-13}  & **1** & **2** & **3** & **4** & **\(r\)** & **Df** & **F** & **F\({}_{\mathbf{0.1}}\)** & **F\({}_{\mathbf{0.05}}\)** & **F\({}_{\mathbf{0.01}}\)** & _Sig._ \\ \hline A & 1.425 & 1.275 & 1.