Dear IIiya,

thank you so much for your answer, but i need whole the norme in PDF  if possible

The area beneath the load-deflection curve indicates the amount of absorbed energy and toughness indices. As per ASTM C1018, I5 is defined as the area under the load-deflection curve up to a deflection of 3 times the deflection recorded when the first crack divided by the area up to the first crack. I10 is defined as the area under the load-deflection curve up to a deflection of 5.5 times the deflection recorded when the first crack divided by the area up to the first crack. I20 is defined as the area under the load-deflection curve up to a deflection of 10.5 times the deflection recorded when the first crack divided by the area up to the first crack.

I have attached ASTM C1018 for your consideration.

Thank you sir 

Thank you sir..

This ASTM standard is withdrawn with no replacement, the currently used one is RILEM TC-80 FMT