Flexural strength
Concrete's resistance to bending, measured by loading a beam specimen until it cracks. It is the governing strength property for pavements and unreinforced slabs.
What does flexural strength mean?
Slabs and pavements fail in bending under wheel loads rather than in pure crushing, so highway agencies often specify flexural rather than compressive strength. Flexural test results are more variable and more sensitive to specimen handling and moisture condition than compressive tests, which is why many specifications correlate to compression for day-to-day control. The relationship between the two is approximate and mix-specific.
In practice
Concrete paving specifications frequently name a flexural value, and the producer then controls production with correlated compressive tests.