Quality of material is an important parameter in structural design. Quality of concrete as a widely used material may be controlled by using pressure testing devices. For this purpose, standard methods are used. However, these methods are difficult, time-consuming and costly. Hence, using non-destructive methods, which are also faster and less costly, has become a must. In this study, ultrasonic pulse velocity and surface hardness values are obtained from samples prepared in the laboratory environment in the context of non-destructive methods and samples collected from an existing concrete structure. Destructive pressure testing is then used to find the compressive strength values of these samples. The study compares and contrasts results from non-destructive and destructive methods. Correlations with discrete and compound methods are obtained with non-destructive methods, and quality evaluation of these correlations is completed.