## 3 Result and Discussion
### Effects of Crepe Rubber and TMQ on Characteristics of Modified Marshall Asphalt  
Modified creep rubber asphalt in its application for road pavement must have the ability to withstand traffic loads better than asphalt pen grade 60/70 [28]. Measuring modified asphalt to withstand road traffic loads can be done by laboratory-scale testing with Marshall stability testing. The Marshall stability value provides an overview of the asphalt's ability to bind aggregates and prevent deformation. The modified asphalt criteria can be successful if the Marshall stability value of asphalt with creep rubber is higher than asphalt pen grade 60/70. The addition of creep rubber to asphalt in its application for road pavement has advantages such as better riding quality, resistance to moisture, higher durability, and rutting due to reduced temperature sensitivity and lower noise levels. Figure 5 shows the increase in the Marshall stability value in samples A1, A2, A3, B1, and B2 compared to pen grade 60/70 asphalt. The highest Marshall stability in samples A2 and B2 with a value of 1426.53 kg and 1403.96 kg or 20-21% of the 60/70 pen grade asphalt. In this study, the optimal asphalt content (KAO) was 5.45% for sample A and 5.50% for sample B with an aggregate composition, as shown in Table 2. Samples B3, C1, C2, and C3 experienced a decrease in the Marshall stability value  
Figure 4: (**A**) Penetration after RTFOT. (**B**) Percentage of decreased penetration after RTFOT. of asphalt pen grade 60/70 due to the penetration of the asphalt in the sample, which approaches and exceeds the asphalt pen grade 60/70. The shift in the penetration value will cause a change in the optimum asphalt content for mixing. The suboptimal bitumen content in the mixture affects the cohesion and adhesion properties of the asphalt. Inappropriate bitumen optimum content will cause the asphalt to be unable to bind the aggregate and easily deform or rutting permanently [29; 30]. In general, crepe rubber's addition to the modified asphalt mixture can harden the asphalt binding with aggregate and increase Marshall stability. However, the addition of crepe rubber that exceeds the optimum will cause the asphalt to be more flexible and create instability when given a load [31]. The addition of TMQ helps strengthen the binding of asphalt with aggregate because TMQ only acts to prevent modified asphalt oxidation. The ability of modified asphalt to fill the aggregate cavity (VFA) affects the value of Marshall stability. The compacted asphalt mixture's cavities significantly affect the asphalt's stability, as shown in Figure 6. The large cavities allow cracks, which lead to a decrease in the stability of the asphalt. In general, cavities that are too large after compaction will cause cracks during Marshall testing. Figure 6 is a piece of the Marshall sample B2 specimen. The red box shows that the large cavity between the aggregate grains causes cracks around the cavity after being loaded. Cracks that arise cause the resulting asphalt's stability is not as high as other research asphalt modifications. The value of cavities filled with asphalt or called void filled aggregate (VFA) shows the cavity's size in the asphalt. VFA has a vital role in maintaining the stability of the mixture while holding loads. Table 5 and Figure 7A shows an increase in the percentage of VFA when the ratio of crepe rubber increases, but the VFA value decreases with 12% crepe rubber. The decreased VFA percentage in sample C  
Figure 5: Marshall stability. Figure 6: Cavities between aggregates in Marshall specimens. with 12% crepe rubber was due to the decrease in the optimum asphalt content, as shown in Table 4. The decrease in the optimum asphalt content affected the aggregate filler to fill the space between the aggregates. The asphalt level that does not reach the optimum can cause a cavity, as seen in Figure 6. The highest VFA value was obtained by sample B, with a 10% crepe rubber with an average VFA of 76.922%.