Dear colleagues,
I'm looking images properly destroyed samples tested using neoprene pads ASTM 1231. Interested primarily samples with a ratio h:d equal to 1:1
Does the way of destruction such as in the picture is correct?
Best Regards,
Wojtek Kubissa
The neoprene pads are to remove the confining effect of the friction at the concrete specimen/steel platen interfaces so that the strength measured is the unconfined uniaxial strength of the concrete. The fracture pattern as observed is what we expect.
Dear Wojtek,
I / WE carried out experiments to determine the effect of different materials between 1:1 specimens on the measurable compressive strength. If the orthogonal displacement is more or less free on the compressed planes, we could measure much less load bearing capacity compared to the case when nothing was in-between the steel plates and the concrete surface. At the same time the cracks became vertical and more or less parallel.
By looking at your sample, similar can be seen, so I would say, it is a correct failure shape.
Just have a look at the two pictures attached here, although they are cubes, but the effect can be seen.
I hope, I could help.
Tamás
p.s Sorry, the second picture is to be flipped by 90 degrees :-)
The neoprene pads are to remove the confining effect of the friction at the concrete specimen/steel platen interfaces so that the strength measured is the unconfined uniaxial strength of the concrete. The fracture pattern as observed is what we expect.
Dear Wojtek,
I think that the way of destruction such as in the picture is correct
hi
With 1:1 (h:d) ratio, restraining effect of the platens can not be fully avoided. Failure cracks for unconfined uniaxial strength should be ideally inclined shear cracks. Nearly vertical cracks indicates that splitting type failure may have occurred. This is common in compressive type loading but then the strength so obtained is not representing the unconfined compressive strength of concrete.
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