CIP 16 - Flexural Strength Concrete WHAT is Flexural Strength ?Flexural strength is one measure of the tensile strengthof concrete. It is a measure of an unreinforced con-crete beam or slab to resist failure in bending.gencies not using flexural strength for field con-trol generally find the use of compressive strength con-venient and reliable to judge the quality of the concreteas delivered.Beam specimens must be properly made in the field.Pavement concrete mixtures are stiff (1/2 to 2 1 / 2 -inchslump).