Effects of shock vibration on concrete

The effects of shock vibration on concrete were studied using a newly developed test method that applies hammer blows to prismatic specimens in the longitudinal direction and evaluates the short- and long-term effects by observing crack formation, measuring the immediate change in ultrasonic pulse velocity and measuring the reductions in 28-day tensile and compressive strengths. A total of 198 prisms cast of typical concrete mixtures with 28-day cube strength ranging from 40 to 60 MPa had been tested at ages of 12 hours to 28 days. The tests revealed that the major effect of shock vibration is the formation of transverse cracks. Based on the test results, the shock vibration resistances of the concrete mixtures at different ages were determined and correlated to their material properties. It was found that the single most important material parameter governing the shock vibration resistance of concrete is the dynamic tensile strain capacity. Finally, several new sets of vibration control limits, which are less conservative than most existing ones, have been established.