Estimation on Compressive Strength of In Situ Concrete with Innovative Pendulum Hammering Test Method

The strength of cast-in-place concrete is obtained using the innovative pendulum hammering test method (PHTM) to reduce structural damage to concrete. A specially developed PHTM device is used to apply a fixed impact force to nails and determine the relationship between the penetration depth of nails and the compressive strength of the concrete. Adverse factors such as aggregate type and concrete moisture content on concrete strength were eliminated and their impact on PHTM test results was avoided. The compressive strength of the tested concrete cube samples ranges from 20 to 50 MPa. The reliability and repeatability of PHTM are superior to the Schmidt hammer (SRH) and pull-out testing methods used in on-site testing. Research has confirmed that PHTM is suitable for in situ testing of prefabricated buildings, beam column joints, and other densely reinforced areas, and unsuitable for coring. Compared with other testing methods, PHTM testing has high accuracy and minimal damage to concrete structures.