Abstract:
The research aims to evaluation of a relationship between two devices used to test
the compressive strength of concrete, one of the concrete destructive tests
[Crushing machine] and the other of non-destructive tests [Schmidt hammer] and
finding equation between the test results between the two devices to help site
engineers to estimate the value of compressive strength for existing buildings.
A number of [36] concrete cubes were used for the tests, divided into [18] cubes
with a compressive strength of 25 MPa and the other [18] cubes with a
compressive strength of 40 MPa. The tests were carried out for concrete ages 7, 14,
and 28 days after treatment by immersing in water. The Schmidt hammer test was
carried out in the vertical direction on the loading of the pressure machine and then
the pressure test was performed on the pressure test machine. Finally, the results
were analyzed using the Excel program and compared the convergence of
compressive resistance between the two devices.
The more accurate equation in concrete grade 25 in 28 days is
𝑌 = .057𝑥2 − 2.713𝑥 + 58.9 and regression
𝑅2 = 0.986, the relationship between Schmidt hammer strength and crushing
machine strength controlled by quadratic equation.
The more accurate equation in concrete grade 40in 28 days is
𝑌 = −0.0072𝑥3 + 0.988 𝑥2 − 45.178𝑥 + 714.42 and regression
𝑅2 = 0.9808, the relationship between Schmidt hammer strength and crushing
machine strength controlled by cubic equation.
