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Re: Granite's Modulus of Elasticity

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Dear K Hemmatyar,

The Young's modulus is the intrinsic property of an undamaged material.  It
is constant.  Usually measured between teh 15 to 85 percentile results in a
tension or compression test.  The closure of micro cracks will cause a
higher E in compression that is now handled in Damage mechanics with a h
value of 0.2 to 0.3 
ie multiply tensil E by this to get compressive.

The Young's modulus for Salem sandstone is in the order of 25 to 50 Giga
Pascals (sorry i never learnt English Units I'm from Aussie land.)

I have recently measured E for bricks at a range of 5 to 55 GPa.  This range
is for same bricks in some cases.  Natural materials even manufactured
bricks are not linearly elastic as exactly as Hooke's Law would suggest.

The Modulus of Elasticity is a measurement of teh Young's Modulus at a
particular point in time and sapce after material has been subject to
loading.  It is only the same for purely ealstic materials or undamaged
materials.

One measures E on a representative sample  For granite your are probably
looking at the same as concrete about a 100 mm cubed to get a continuum
measurmement

If you are using the results remember
Micro results are effected by the test method so they may be high.

Meso results apply to small areas like an area beneath a building.  In hte
modelling I do at this scale I allow an E of about 10-20 GPa.  The material
is goiong to be cracked and splintered.  Your problem is what you are using
the modelling for if it is for a dynamic analysis of a building I would use
10 to 20.

If it is for a material to be used in a building I would get it measured at
a good lab.  I would send it to Abrams in Urbana.  If you are using mortar
in between it will have an E of 1 GPa tops.  This will affect the results
depending on the thickness of the two materials.  DAvidge book on ceramics
has a formula to solve this problem I can send it to you if you like.

Failing that I would ask the Coloroda School of Mines I think thats it.
Actually I would ask them anyway.

John Nichols

I trust this helps.

F
seaoc(--nospam--at)seaoc.org,Internet writes:
1.   Does any one know what is the Granite's Modulus of elasticity (roughly)
or where can I get it? (it is Sunday!)

2.   Question: Modulus of Elastisity and Young's Modulus is the same but
does "Modulus of Rupture" refer to the same property?

Thanks 

K. Hemmatyar, P. Eng. (structural)
Vancouver, B.C. 


Reference "SOIL MECHANICS" by Lambe and Whitman

Modulus of elasticity ranges from 10.6 to 12.5 x 10^6 psi

Modulus of rupture os a different property.  I can't find it in a text but if
you recall for concrete modulus of elasticity is 57,000*SQRT(f'c) and modulus
of rupture is 7.5*SQRT(f'c)


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