This chapter aims to establish an appropriate model for predicting the strength properties of cast-in-situ concrete and pumpable structural concrete elements using nondestructive testing methods. The widely used nondestructive testing methods like Schmidt rebound hammer tests and ultrasonic pulse velocity tests were employed to develop the new empirical model suited for the structures, which can be preserved for assessing the performance periodically. M20-grade normal concrete to M60-grade high-strength concrete were considered for cast-in-situ type concrete and pumpable concrete for establishing the models. The cube concrete specimens were prepared in a laboratory environment and also at the delivery point of concrete construction to determine the actual compressive strength by the destructive method. The nondestructive evaluations were made utilizing the same specimens before the destructive testing was conducted to develop the empirical relationship. Later, the structural elements of selected existing buildings were tested, employing the nondestructive testing methods to evaluate the performance of concrete with the aid of the predicted model. Three different model categories, such as linear, exponential, and power models, were considered to select the best-suited correlation. Finally, a linear model was suggested for rebound number and power models for the ultrasonic pulse velocity results with higher regression coefficients.