## 3 Result and Discussion  
### Effects of Crepe Rubber and TMQ on Modified Asphalt Penetration  
Penetration describes the physical hardness level of the asphalt and is a parameter for classifying the quality of asphalt. Asphalt with a lower penetration value is more suitable for use in areas with hot climates. Asphalt with low penetration values generally has higher softening points and rutting resistance, thus extending the asphalt life. Asphalt test results using an automatic penetrometer as presented in Table 4. Asphalt pen grade 60/70 has an asphalt penetration value of 70.2 dmm. Modified asphalt creep rubber and antioxidant TMQ decreased and increased penetration of asphalt compared to pen grade 60/70 asphalt. Figure 1 shows that modified asphalt tends to increase penetration and the increasing ratio of creep rubber and TMQ. The penetration values of Samples A1, A2, B1, B2, C1, and C2 as a whole are lower than asphalt pen grade 60/70, while samples A3, B3, and C3 have a higher penetration value than asphalt pen grade 60/70. The lowest penetration value is in sample A1 with a penetration value of 61.30 dmm or a decrease of 12.67% from the 60/70 pen grade asphalt. The highest penetration is in the C3 sample with a penetration value of 78.30 dmm or an increase of 85.61% from the 60/70 pen grade asphalt. In general, the decrease in asphalt penetration is caused by an increase in the ratio of creep rubber in asphalt,  
Figure 1: Penetration. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Sample**} & **Optimum** & \multirow{2}{*}{**Marshall**} & \multirow{2}{*}{**VFA (\%)**} & \multirow{2}{*}{**VIM (\%)**} & \multirow{2}{*}{**VMA (\%)**} & **Flow** & **MQ** \\  & **Asphalt** & & & & & **(mm)** & **(kg/mm)** \\ \hline A1 & 5.45 & 1336.24 & 68.737 & 4.706 & 15.082 & 3.370 & 396.510 \\ A2 & 5.45 & 1426.53 & 67.928 & 5.374 & 16.555 & 3.710 & 3  
increasing the absorption capacity of the light fraction of asphalt and accelerate the distribution of melted crepe rubber [16]. The absorption of light fractions of asphalt, such as saturate and some aromatic compounds by crepe rubber, will physically change the crepe rubber to expand and form a viscous gel [17]. An increase in the ratio of crepe rubber that exceeds the optimum will cause the asphalt to become soft. The melted crepe rubber is not evenly mixed in the asphalt and accumulates on the asphalt-rubber mixture. The accumulation of rubber changes the modified asphalt mixture's surface to be softer so that the penetration value increases during testing. An increase in the ratio of crepe rubber that exceeds the optimum will cause the asphalt to become soft. The melted crepe rubber is not evenly mixed in the asphalt and accumulates on the asphalt--rubber mixture. The accumulation of rubber changes the modified asphalt mixture's surface to be softer so that the penetration value increases during testing [8]. Several factors cause the accumulation of melted crepe rubber on the asphalt surface, including the slow stirring speed during the mixing process, which is the main cause of the accumulation of melted crepe rubber on the surface asphalt mixture-crepe rubber. During the mixing process of asphalt with crepe rubber, the stirring speed plays an important role in the distribution speed of melted crepe rubber in the asphalt [8; 9]. The direct use of crepe rubber takes a very long time to melt. The solution to speed up crepe rubber's melting process is to use high temperatures, but this has drawbacks. The melting process of crepe rubber at 200 \({}^{\circ}\)C for a long time can cause degradation and damage the polymer structure of crepe rubber or asphalt. Degradation of structural damage to the crepe rubber is undesirable because it will affect the asphalt sample's physical properties to become softer [18]. Samples A1, A2, A3 has the same ratio but have a penetration value that increases with increasing levels of TMQ in the mixture.