is the classification system for asphalt cement, defined in AASHTO (American Association of State Highway Transportation Officials) Specification M20, and based on tests for penetration (asphalt), flash point, ductility, purity, etc., as specified in test method ASTM-D-946. There are five standard grades, ranging from hard to soft: 40-50, 60-70, 85-100, 120-150, and 200-300. Asphalt cement is also classified by viscosity grading.