"This paper presents comparisons of pull-out strength of concrete with compressive strength of cylinders and cores, pulse velocity and rebound number. Briefly, a pull-out test, which is relatively a new technique, measures with a special tension ram the force required to pull out a specially shaped steel rod whose enlarged end has been cast into the concrete. In this study pull-out tests were performed on 2 x 2 x 1-ft (610 x 610 x 305-mm) concrete blocks. Compressive strengths were obtained on 4 x 8-in. (102 x 203-mm) and 6 x (12-in. (152 x 305-mm) cylinders; also 4 x 8-in. (102 x 203-mm) cores were drilled from the blocks and tested in compression. In addition, pulse velocity measurements and Schmidt rebound hammer readings were also taken on the blocks. The analysis of the test data shows that a significant correlation exists between the compressive strength of cylinders cure under standard conditions and the pull-out strength of concrete. This is equally true for the compressive strength of the cores drilled from the concrete blocks. For the same concrete mix, the pull-out strength increased with increasing age, indicating the possible usefulness of these tests for comparative studies. The ratio of the pull-out strength to the cylinder compressive strength decreases with increase in the compressive strength of concrete. At 28 days, this ratio varies from 24 per cent for 2860 psi (19.7 MPa) concrete to 18 per cent for 7510 psi (51.8 MPa). In general, for any strength level, the ratio does not change significantly with age. The pull-out strength is of the same order of magnitude as the direct-shear strength of concrete indicating that the pull-out test result may be a measure of the direct-shear strength of concrete."--Synopsis, page i.