There are many equations; some of them are famous and the other from researchers. See the attachment.

There are many equations; some of them are famous and the other from researchers. See the attachment.

Thank you so much

Dear Mr. Wissam Nadir, thank you for sharing this question.

As I know, there is no general approved equation (till now) that links the ultrasonic test with the compressive strength property of concrete. There are many formulae in the literature produced for particular works. It is difficult to do that because the concrete is a heterogeneous material and there are various parameters (such as type and quantity of its constituents, curing, age, environmental conditions....etc.) can affect its behavior.

Best Regards

Dear Dr. Mohammed, thank you very much.