Evaluation of Early-Age Concrete Compressive Strength …
Compressive strength increased with the surface wave velocity in each case. The coefficient of determination (R 2) is 0.746 in Figure 11 a and 0.9083 in Figure 11 b. Because the concrete strength for form removal is less than 10 MPa [1,2,3,4,5,6,7], the measured values need to be compared with the fitted graph in the low-strength region.