3-point bend test and fractography analysis were carried out to study the effect of span length (40, 60, 80, 100, 120, 140 mm) on mechanical properties such as flexural strength, stiffness, strain energy and flexural modulus. The flexural strength in terms of the span length-deflection ratio was plotted to determine the transition point from shear to flexural fracture. The correlation between flexural strength, mirror strength as a function of the span length was investigated as well. The results showed the span length had affected the flexural strength as well as the mirror strength. We also reported that the mirror radius was inversely proportional to the flexural strength and the mirror constant was fluctuated in the range of 45.1MPa • (mm)1/2 to 67.4MPa • (mm)1/2.

Keywords: 3-point Bend Test, Flexural Strength, Mirror Radius, Mirror Constant, Span Length.