## 3 Result and Discussion
### Effects of Crepe Rubber and TMQ on Characteristics of Modified Marshall Asphalt
The average percentage of VFA in sample C was higher than that of sample A, but the Marshall stability sample A was higher than that of Marshall stability sample C.  
Figure 7: _Cont._  
The decrease in Marshall stability and the percentage VFA of sample C was due to several factors, including a smaller portion of optimum asphalt content. The optimum bitumen content, which is too small, will make the asphalt layer covering the aggregate thin and decrease the asphalt's adhesion properties [32]. The addition of crepe rubber and TMQ to the asphalt provides a significant change in modified asphalt density. As shown in Figure 7D, increasing the ratio of crepe rubber and TMQ changes the density of modified asphalt decreases, decreasing density is the cause of decreasing VFA percentage [33]. The increase in crepe rubber and excessive TMQ also creates instability because the binding power of asphalt with aggregates is higher than that of rubber. Combining these three things causes sample C to be no better than sample A in load-bearing stability. The percentage of VFA is closely related to the percentage of Void in mixture/air void (VIM) and void mineral aggregate (VMA). Increasing the percentage of VFA and decreasing the VMA value plays a vital role in the asphalt mixture's mechanical properties. In Figure 7B and Table 5, the increase in crepe rubber causes a decrease in VMA, the smallest VMA percentage in sample C with an average of 14.6%. The VMA percentage is too small; the mixture can experience durability problems because it forms a thin layer on the aggregate. Too large a percentage of VMA is also not good for asphalt mixtures because the stability will be very low [32]. Void in mixture/Air void (VIM) indicates the asphalt tightness and pore properties of asphalt. The percentage of VFA strongly influences VIM in the mixture. The small VFA percentage value indicates many voids between the asphalt aggregate mixture, as shown in Figure 8A. The VIM percentage represents the flexibility and durability of the asphalt and aggregate mixture. Asphal with a VIM value that is too large indicates that the asphalt is not waterproof and is susceptible to oxidation and deformation when it is loaded. The VIM value that is too small also causes the mixture to become stiff and cracking due to the absence of cavities for the shifting aggregates. The smallest VIM value was obtained by sample B, with an average of 3.302%, as shown in Figure 7C and Table 5. The filler ratio has a significant effect on the percentage of VIM because filler has a vital role in filling the voids between aggregates. Additionally, the filler functions to make the mixture waterproof, as shown in Figure 8B. Figure 7: (**A**) VFA. (**B**) VMA. (**C**) VIM. (**D**) Bulk density modification asphalt. The asphalt mixture's stability can be influenced by several factors that significantly differ from other studies' results. The factors that affect the asphalt mixture's stability include the optimum asphalt content in the mix, the gradation and composition of the aggregate in the mix, the penetration of the asphalt-rubber used, the viscosity of the mixture, and the mixing and compaction temperature [34]. Increased bitumen stability provides better asphalt durability in withstanding traffic loads, increases rutting resistance, reduces deformation at high temperatures, reduces fatigue resistance, and prevents premature aging. Based on the modified crepe rubber asphalt's characterization results, it was found that the asphalt with the addition of 10% crepe rubber and 2% TMQ (sample B2) had the most optimum conditions. Therefore, sample B2 was subjected to further testing to determine the asphalt performance after short-term aging and long-term aging.