To determine the Flexural Strength of Concrete, which comes into play when a road slab with inadequate sub-grade support is subjected to wheel loads and / or there are volume changes due to temperature / shrinking.

Specimen:

Tamping bar (40 cm long, weighing 2 kg and tamping section having size of 25 mm x 25 mm)

Flexural  test machine– The bed of the testing machine shall be provided with two steel rollers, 38 mm in diameter, on which the specimen is to be supported, and these rollers shall be so mounted that the distance from centre to centre is 60 cm for 15.0 cm specimens or 40 cm for 10.0 cm specimens. The load shall be applied through two similar rollers mounted at the third points of the supporting span that is, spaced at 20 or 13.3 cm centre to centre. The load shall be divided equally between the two loading rollers, and all rollers shall be mounted in such a manner that the load is applied axially and without subjecting the specimen to any torsional stresses or restraints.

Span 300mm, adjustable.

Roller width 260mm.
Roller diameter (up 15mm, lower 10mm)

EN 12390-5 Testing hardened concrete-Part5: Flexural strength of test specimens