Question
If concrete compression test not pass, So Schmidt hammer test will be adopted as an alternative test to confirm concrete strength?

Answer
Schmidt hammer test is support on elastic rebound of hammer which presses on concrete surface and it method surface hardness of concrete. Because test is too sensitive to presence of aggregates and voids at concrete surface, it is essential to take more than 10 readings over area of test. Though, it has to be noted that Schmidt hammer test process surface hardness only but not strength of concrete. So, it might not be considered a high-quality substitute for concrete compression test.