Method, device, and system for testing static contact angle of reagent asphalt

A method for testing static contact angle of reagent asphalt, comprising the following steps:

• acquiring a side image of a stable droplet formed by a test reagent on asphalt surface, and determining a position of a baseline in the side image, wherein a height direction of the droplet is defined as a y axis coordinate direction, and a vertical direction of the droplet is defined as an x axis coordinate direction, the baseline represents a contact surface between the reagent droplet and the asphalt, a y-coordinate value of the baseline is defined as J;
• cropping the side image to obtain a droplet image, and extracting droplet contour points in the droplet image, wherein the extracted contour points comprise a complete droplet contour, an aperture at a center of the droplet, and noise points, extracting droplet contour points in the droplet image comprising:
• extracting horizontal and vertical coordinates of all points with a pixel value of 1 in the droplet image to form a contour image, and
• assigning the horizontal and vertical coordinates of the points to variables x and y respectively as x and y coordinate values of the contour points;
• screening out effective contour points corresponding to contours of two sides of the droplet from the droplet contour points, comprising:
• exchanging x and y coordinate values of the contour image of the contour points by rotating the contour image 90° counterclockwise;
• selecting the contour points whose x-coordinate values are less than J;
• filtering out the contour points of the aperture and the noise points to maintain the complete droplet contour;
• performing cubic polynomial fitting on the effective contour points to obtain curve function of contour curves on both sides;
• calculating contact angle value from the curve function and the position of the baseline.