A new preparation method and imaging parameters of asphalt binder samples for atomic force microscopy

Abstract

The sample preparation and the image acquisition method of asphalt binders are of importance to atomic force microscopy (AFM) imaging quality, especially for the peak force quantitative nanomechanical (PF-QNM) mode. Based on the heat-cast method, a new hot asphalt pouring method for asphalt binder AFM sample preparation was developed in this study. For different probe types and test parameters, samples of the commercial SK-70# asphalt binder prepared by the proposed technique were subjected to PF-QNM tests. The experimental results obtained proved the feasibility and stability of the proposed sample preparation method. Aluminum-coated probes with a nominal spring constant range from 0.4 to 6 N/m were found to furnish the optimal solution to the construction of topography and nanomechanical property maps of SK-70#. The variation of test parameters has shown that the peak force setpoint and peak force tapping (PFT) gain strongly influenced the microstructure topography and nanomechanical property maps. Using reasonable probes and imaging parameters, good AFM maps could be obtained. In this research, only one asphalt binder was tested and the effect of other probe types and test parameters on other asphalt binders need to be further studied in the future.