What is the correlation of stress level (in stress-controlled mode) for Indirect Tensile Fatigue Test (ITFT) with that of field load on pavement?
I am trying to predict fatigue life of pavement (using different materials) in ITFT set-up at stress-controlled mode. According to some standards and literature different stress levels (kPa) have been utilized (e.g., 200, 250, 300, 350 kPa etc). In some cases, researchers used stress level of 30, 50 and 70% of Indirect tensile strength (ITS) for ITFT.
However, I am wonder how these stresses are correlated to field loading conditions. What is the equivalency in laboratory stress level for ITFT and field traffic load?
Dear Muhammad
The stress level in fatigue can be. Lower than that of the yield strength of the tested sample materials. One choses hight stress level, i.e.,60 or 70 % 0f the yield strength,because of the intention of using high stress low cycle fatigue test.In contrast, one uses low stress level ,i.e.,10 or 30 % ,of the yield strength ,because the intention of using low stress high cycle fatigue test.So.in your case the stress level varies dependent on the traffic load and on how frequent the traffic on the pavemet samples. So.you ought to use both modes of the fatigue to test the pavement sample in order to get enough data base to make a decision what best works for you.
I wish you all a happy holiday season with peace in mine, harmony with the surrounding, and progress in life for the best of man kinds.
Khaled J. Habib
Thank you for detail reply. Yes I am doing ITFT at various stress levels (high, medium and low) in order to get enough data for fatigue prediction.
However, I still have confusion that how these stress levels have relationship with the load application in field.
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