Compression Strength

[Lubojulo]

I understand that the ASTM method for compression strength of cement normally gives lower results than the method used in EU. Does anyone know if there is a way to estimate the difference? Does anyone know if there is a way to say that the ASTM results are, normally, X% lower that results achieved by the EU method?
Much appreciate your help!

Lubojulo

 

[csd72]

Is it because one is a cube test and one is a cylinder? If so, I have seen a direct comparison of these methods which gave a general ratio. Will see if I can find it.

 

[Lubojulo]

Thanks csd72!
I am not sure if the difference is cube v. cylinder. I think both methods use cubes but different size. But I am not sure. I am trying to put my hand on the EU method. Appreciate your help!
Lubojulo.

 

[cvg]

what ASTM test method are you interested in - there are many? And do you mean mortar or concrete? (cement has no compressive strength)

http://www.astm.org/Standards/cement-and-concrete-standards.html

 

[Lubojulo]

cvg - you are correct. I am interested in measuring the compression of mortar. The ASTM method is C-109.
Thanks!

lubojulo

 

[concretemasonry]

As I recall (actual standard not available now), ASTM C109 is a laboratory test for measuring properties of mortar. It is done using a non-absorptive cube mold and does not represent the actual strength of the mortar used in place. It is just used for laboratory compression results and does not measure other properties that may be much more important.

In the big or "over-all" picture, the compressive strength of mortar has little effect on the strength of a wall. As an example an actual 4800 psi 8x816 hollow block prism (face shell bedding) can be constructed with 2200 psi mortar.

Reading ACI 530 code will provide a good summary of the behavior of masonry and the relationship to mortar and masonry unit strengths.

Dick

Engineer and international traveler interested in construction techniques, problems and proper design.

 

[sdz]

The cube strength is about 25% higher than the cylinder strength.

 

[BigH]

Perhaps you need to think about the specification of the cement. ASTM OPC has a requirement of 12 MPa at 3 days, 19 MPa at 7 days and only 28 MPa at 28 days (optional). This is rather low when compared to OPCs from other countries. In India, they have OPC 33, OPC 43 and OPC 53 - from my last time there the OPC 43 was becoming the norm and some manufacturers were using OPC 53. What does the 33, 43 and 53 mean? It is the 28-day strength requirement of the cement and is a function of the finess of the grind. Notice that this is much different than the ASTM OPC. This is probably what you are talking about.