# Rheological Characteristics Evaluation of Bitumen Composites Containing Rock Asphalt and Diatomite
## 5 Conclusions  
In this study, a series of tests were conducted in order to evaluate the rheological characteristics of petroleum bitumen modified by rock asphalt (RA) and diatomic. Based on the results and discussion, some conclusion can be drawn as follows.  
(1) The addition of RA and diatomic significantly improved the apparent viscosity of petroleum bitumen binders. When the test temperature was 175 \({}^{\circ}\)C, the apparent viscosity of 13% RA+7% diatomic composite-modified asphalt was 212.5% higher than that of petroleum bitumen.  
(2) The master curves indicated that the addition of RA and diatomic significantly increased the dynamic shear modulus of petroleum bitumen binders. Further, a higher dosage of RA and diatomic resulted in a higher dynamic shear modulus. This increase was desirable for an improved  
Figure 5: The BBR test results: (**a**) creep stiffness and (**b**) m-value.  
high-temperature performance of bitumen. The dynamic shear modulus of the 13% RA+7% diatomic composite-modified asphalt was 427.0% higher than that of petroleum bitumen at 60 \({}^{\circ}\)C and 10 Hz.  
(3) The master curves indicated that the addition of RA and diatomite effectively enhanced the rutting performance and deformation resistance of petroleum bitumen binders. The rutting index G*/sin\(\delta\) of the 16% RA+9% diatomite-modified asphalt was approximately 20 times that of the petroleum bitumen in the temperature sweep tests.  
(4) At different temperatures, the fatigue factor \(\mid\)G*\(\mid\)\(\cdot\)sin\(\delta\) of petroleum bitumen was 5 times lower than that of the modified bitumens, which indicated that the fatigue performance of bitumen binders decreased with the addition of RA and diatomite.  
(5) At \(-\)12 \({}^{\circ}\)C, the m-value of the 13% RA+7% diatomite composite-modified asphalt was 20.7% lower than that of petroleum bitumen. The low-temperature performance of bitumen binders weakened with the addition of RA and diatomite.  
Conceptualization, W.H., Data curation, W.H., J.T. and P.Y.; Formal analysis, W.H., D.W., X.L. and B.T.; Investigation, J.T. and P.Y.; Methodology, D.W., P.H. and B.T.; Project administration, P.H. and X.L.; Writing-original draft, W.H.  
This research was funded by National Natural Science Foundation of China (Grant number [51578248, 51809046]); Research Start-up Funds of Dongguan University of Technology [ZJ20170428, GC300502-29, GC300502-32]; The Science and Technology Planning Project of Guangdong Provincial Department of Transportation [2014-02-004]; and Open Fund of Key Laboratory of Transport Industry of Bridge Detection Reinforcement Technology (Chang'an University) [300102219527, 300102219528].  
This work is supported by Higher Education Teaching Reform Project of Department of Education of Guangdong Province [2018-180], Production-University Cooperation and Education Project of Higher Education Department of Ministry of Education [201801317027], Higher Education Research Project of Dongguan University of Technology [2017 GYB06]. The authors gratefully acknowledge their financial support.  
The authors declare no conflict of interest.