If we use concrete cubes instead of concrete cylinders for finding the stress-strain curve, what effect it will produce? Will both be the same or will there be an effect of h/d ratio?
Strength of cube and cylinder (if h/d=1) will be different. It is related to the contact area of the samples and the press and form of this area. For strain measurement using samples (cylinder or prism) with h/d=4. This is done to eliminate the undue influence of contact friction on the sample behavior.
@sergey Thanks for the answer. So what's your opinion, will there be any difference in stress-strain curve or not?
Of course it will be. Strength of cube will be larger than cylinder (if h/d=1). And deformations of cube (especially transverse strain) will be larger too. If you use prism and cylinder with h/d=4 stress-strain curve will be more similar.
Why do you want to use cubes samples? As I know for take stress-strain curve according to the standards in all countries need to use prisms or cylinders.
@sergey, due to some reasons, I am not able to use cylinders/prisms. Now I want to use the cubes. Is there any relation(empirical) between stress-strain curve of cube and cylinder?
The stress strain curve of cylinder and cube will be different. Since an uniaxial compression load is applied, the cylinder will give more accurate result because the stress and strain in lateral direction will be same in all directions. This is not so with cube sample. The failure model will be different if compared with cylinder sample.
yes
significant different
the stress strain curve you speak and know is from standard cube so when your dimensions be change so your result in stress strain will be change.
The confinement effect will be more in cube sample, so the ultimate stress in cube will be greater than in cylinder.
Dear Arbab,
From the design code:
EN 1992-1-1 (2004): Eurocode 2: Design of concrete
structures - Part 1-1: General rules and rules for buildings
an approximate relationship between characteristic concrete strength for cyllinders and cubes can be deduced:
fck = 0,8 fck,cube
fck - characteristic axial compressive strength (cyllinder)
fck,cube - characteristic cube strength
See the attached file.
Best Regards,
Bartosz Grzeszykowski
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