Dear Zaid:

Please see the following papers for a formula for concrete compression strength and Schmidt Rebound Number:

Article Assessing the strength of reinforced Concrete Structures Thr...

This paper indicates good correlation between the two quantities.

The is a followup paper provides similar information from an in-situ investigation:

Article Correlation between Schmidt Hammer and destructive compressi...

I hope that this helps you.

Sincerely,

Arturo

The company that manufactured Schmidt Hammer attaches the formula with it.

pl check it

Article Correlation between Schmidt Hammer and destructive compressi...

thank you for your answers, I so appreciated

The hammer test is meant to study the uniformity of concrete, not the strength. There is an ASTM about the use of this NDT. Research and producers have provided formulas that relate hammer measurements to compressive strength, but I would not trust them if they aren’t complemented with some destructive tests.

If the structure you are evaluating is old, most likely, the surface will be affected by calcium/carbon reactions, which make the surface very hard. This can cause huge errors in the interpretation of the hammer test.

Dear Dr. Victor can you send to me these researches and lectures related to hammer concern to compression strength

thank you so much

Dr. Zahra,

Please see the ASTM C805/C805M and its references.

Also, this webpage explain quite well the use and the problems: http://www.gbg.co.uk/index.php?page=strrebound

Formulas can be found in the manufacturer manual. You can directly contact Proceq for that matter.

https://www.proceq.com/compare/schmidt-hammers/

Hope, it helps.

Regards.

thank you so much Dr. Victor Aguilar Vidal

Dear Zaid,

Each concrete hammer test has several calibrated curves (also called conversion curves) provided by the manufacturer. These conversion curves display the relationship between compressive strength and rebound number. So, you just need to check the manual of the rebound hammer that you are using in your research.

For example, the link below gives detailed information about how to estimate compressive strength of concrete using Proceq-Schmidt Rebound Hammer

https://www.proceq.com/compare/schmidt-hammers/

Good Luck!

There are some misgiving in the use of Schmidt hammer to determine strength of concrete. I think the technique should not be used in isolation but with other techniques as well as core boring. Meanwhile, the correlation curves given by the manufacturer could only be used as guide because you are possibly be using different concrete.