## 3 VVCM Evaluation
### Gradation Variation  
After forming the VVTM specimens and PCT specimens, a compaction mix extraction test was conducted. The gradation changes before and after extraction can be seen in Table 7. The differences in the pass rates for each grade after extraction can be seen in Table 8.  
Based on Table 8, it is evident that the degree of aggregate damage inside the PCT specimens is significantly higher than that in the VVTM specimens. The grade with the largest change in aggregate pass rate is 37.5 mm, with a variation of 7.4%, indicating that the damage rate for the 37.5-53 mm grade aggregate reaches 17.6%. This can be attributed to several factors. During the formation of PCT specimens, there is minimal relative displacement of the aggregates. The coarse aggregates embed and intrude each other and are forcibly fractured under vertical pressures exceeding the crushing value of the material. As the primary aggregate of the LSM-50 mixture, the 37.5-53 mm grade aggregate provides a significant proportion of the specimen's embedment force. The higher the degree of damage, the greater the decline in this embedment force. Furthermore, the substantial damage to the primary aggregate disrupts the original embedment structure. This not only results in a decreased load-bearing capacity of the overall mixture but also causes the mineral aggregate framework to be propped open by the fractured aggregates. However, without excess asphalt mortar to fill these voids, the porosity of the specimen increases. This subsequently leads to a reduction in the cohesion and internal friction of the mixture, causing a decline in the strength of the specimen.  
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Contents**} & \multicolumn{8}{c}{**Percentage Passing (\%) for Sieve Size (mm)**} \\ \cline{2-10}  & **53** & **37.5** & **31.5** & **26.5** & **19** & **16** & **13.2** & **9.5** & **4.75** \\ \hline Initial gradation & 100.0 & 58.0 & 54.0 & 50.0 & 46.0 & 44.0 & 42.0 & 40.0 & 35.0 \\ VVCM & 100.0 & 59.2 & 55.6 & 51.8 & 48.1 & 46.0 & 43.6 & 40.6 & 35.6 \\ PCT & 100.0 & 65.4 & 58.4 & 55.7 & 49.4 & 47.2 & 45.0 & 42.7 & 37.2 \\ \hline \hline \end{tabular}
\end{table}
Table 7: Comparison of gradation crushing before and after compaction.  
\begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Contents**} & \multicolumn{8}{c}{**Percentage Passing (\%) for Sieve Size (mm)**} \\ \cline{2-10}  & **53** & **37.5** & **31.5** & **26.5** & **19** & **16** & **13.2** & **9.5** & **4.75** \\ \hline VVCM & 0.0 & 1.2 & 1.6 & 1.8 & 2.1 & 2 & 1.6 & 0.6 & 0.6 & 11.5 \\ PCT & 0.0 & 7.4 & 4.4 & 5.7 & 3.4 & 3.2 & 3 & 2.7 & 2.2 & 30.0 \\ \hline \hline \end{tabular}
\end{table}
Table 8: Differences in pass rates for each grade after extraction.  
In summary, specimens of LSAM-50 formed using the VVTM exhibit higher mechanical strengths, and the extent of internal aggregate damage is considerably lower. This ensures greater stability and reliability in indoor mechanical strength tests. Therefore, it is recommended to use the VVTM for molding specimens of LSAM-50 mixtures.  
Influence of Volume Parameters on the Mechanical Properties of LSAM-50 Asphalt Mixture and Design Criteria