# Performance Evaluation of Recycled Asphalt
## 3 Results and Discussions for the RAP Materials
### Specimens Preparation by Using Vibration Compaction and Heavy-Duty Compaction Methods
#### 4.1.1 Specimens Preparation with Different Compaction Methods  
First, re-water was added into the emulsified asphalt, then the emulsified asphalt here comprises of matrix asphalt, emulsifier, auxiliary reagent and water; wherein the emulsifier uses cationic emulsifier, and the auxiliary reagent uses acid-base auxiliary reagent. Then added into RAP materials together,  
\begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline sieve size (mm) & 19.0 & 16.0 & 13.2 & 9.5 & 4.75 & 2.36 & 1.18 & 0.6 & 0.3 & 0.15 & 0.075 \\ \hline Pass percentage (\%) & 100 & 97.6 & 85.1 & 72.1 & 48.2 & 32.9 & 21.8 & 16.1 & 11.6 & 7.9 & 5.9 \\ \hline \end{tabular}
\end{table}
Table 2: Grading for cold recycling test and research.  
stirring for 45 s, and the specimens were molded by vibratory compaction. Two groups of experiments were carried out, and five specimens were molded in each group. Using 2% and 3% asphalt content, respectively, to obtain two groups of optimum moisture content [34].  
On the premise of optimum moisture content, vibration compaction was adopted to mold the specimens, and the influence of wetting water on the specimens was researched, that is, whether wetting water needs to be added into RAP materials first. The adding method of emulsified asphalt without adding wetting water is as follows: Firstly, the designed additional wetting water is added into emulsified asphalt, mixing for 45 s, then the mixed emulsion is added into the RAP materials and mixing for 45 s again [35]. The adding method of emulsified asphalt with adding wetting water is as follows: Firstly, the designed additional wetting water is added into the RAP materials, mixing for 45 s, then the quantitative emulsified asphalt is added and mixing for 45 s again.  
Using 2% and 3% asphalt dosage respectively, four groups of tests (2% asphalt dosage without wetting water, 3% asphalt dosage without wetting water, 2% asphalt dosage with wetting water, 3% asphalt dosage with wetting water) were carried out. Six specimens were molded in each group of tests, and the maximum dry density figures were measured and analyzed.  
The preparation process of heavy-duty compaction and vibration compaction specimens is the same, and the experimental results are analyzed [36].  
In order to compare the influence of wetting water on compressive strength furtherly, in this paper, based on the recommended gradation, appropriate changes are made, and the amount of cement added was 2%, the specimens were molded by vibratory compaction method, two specimens were prepared for each gradation. The compressive strength was measured seven days later, and the influence of the wetting water on the strength was further analyzed [37]. The gradation design is shown in Table 3.  
Five matrix asphalt contents of emulsified asphalts were selected for research, which were 0% (Pure water), 30%, 40%, 50%, and 60%, respectively. A total of 30 specimens were prepared by vibration compaction, the maximum dry density and the optimum fluid content of emulsified asphalt with different matrix asphalt contents were obtained by selecting different fluid dosages.