研究目的
To characterize the asphaltic cement penetration grade 30/45 based on the morphology of nanostructures called 'bee' structure and its modification when diluted in heptanes or toluene.
研究成果
The bee structures in bitumen are composed of protrusions likely made of asphaltenes, as they persist after heptane treatment (which dissolves maltenes) but are completely dissolved by toluene. This suggests that asphaltenes form the rigid parts of the bees dispersed in a maltenic matrix.
研究不足
The study is limited to surface analysis using AFM, which may not capture bulk properties. The use of specific solvents (toluene and heptane) and sample preparation methods (spin coating) could introduce artifacts. The conclusions are based on morphological observations without chemical composition analysis.
1：Experimental Design and Method Selection:
The study used Atomic Force Microscopy (AFM) in tapping mode to observe the morphology of bitumen samples. Samples were prepared by spin coating, and surface dissolution was induced with solvents to study the effect on nanostructures.
2：Sample Selection and Data Sources:
Asphaltic cement penetration grade 30/45 (CAP 30/45) was supplied by REDUC. Samples were prepared as films on glass substrates.
3：List of Experimental Equipment and Materials:
Atomic Force Microscope (JPK OA microscope, Berlin – Germany), NSC 14 (Ti-Pt) tip, heating stage, solvents (toluene and n-heptane, spectroscopic grade from VETEC), glass plates, spin coater.
4：Experimental Procedures and Operational Workflow:
CAP samples were heated to 440K and spin casted on glass to produce films. Films were cooled and stored for 24 hours. AFM analysis was performed in tapping mode. Surface attacks were done by adding 200 μL of toluene or n-heptane to the films, followed by drying and storage before AFM imaging.
5：Data Analysis Methods:
AFM images were analyzed for topographic and phase contrast features. Line profiles were used to measure heights and phase shifts of nanostructures.
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