EFFECT OF PUMPING ON PROPERTIES OF BRIDGE CONCRETE

Pumping of concrete is widely used in large highway projects because of convenience and economy of placement. The short-term effects of pumping on the durability of concrete is well documented, whereas the long-term effects on concrete durability is not known. Both types of effects were studied through collection and testing of 73 concrete samples from the Florida Department of Transportation bridge construction sites before and after pumping. The tests performed were air content, slump, unit weight, compressive strength, rapid chloride permeability, and water permeability. The air content and the slump of concrete decreased by about 1% and 13 mm (0.5 in.) on average, respectively, because of pumping. The unit weight and compressive strength of concrete were found to increase by about 24 kg/cu m (1.5 pcf) and 1.83 MPa (266 psi), respectively, because of pumping. Although test results are not statistically significant, pumping decreased the water and chloride ion permeabilities in the majority of tested samples. Results show that pumping does not have detrimental effects on concrete properties. In many cases, it results in stronger, denser, and more durable concrete. It is suggested that pumping be continued as a means of concrete placement in Florida Department of Transportation projects with confidence.