THE ULTRASONIC TEST FOR THE EVALUATION OF PERFORMANCE OF CONCRETE AIRPORT PAVEMENTS

none3In accelerated paving techniques, the pavement gains strength quickly, thus reducing the construction schedule. Accelerated-concrete paving also can speed reconstruction reducing the time that passenger loading gates are out of service at commercial airports for apron reconstruction. As a consequence, non-destructive testing is increasingly using to adequately determine the compressive strength at early ages. Pulse velocity is an available nondestructive test for determining concrete strength at early ages. A true nondestructive test, it measures the time required for an ultrasonic wave to pass through the concrete from one transducer to another. The distance between the transducers is divided by the travel time to obtain the pulse velocity. As pointed out by many researchers, the value of the Ultrasonic Pulse Velocity (UPV) is affected by numerous factors, including the properties and proportion of the constituent materials, aggregate content and types, age of the concrete, presence of microcracks, water content, stresses in the concrete specimen, surface condition, temperature of the concrete, path length, shape and size of the specimen, presence of reinforcement, and so on. According to scientific literature in the field of ultrasonic investigations, there are numerous experimental formulations able of correlating the concrete compressive strength with the measurement of a non-destructive parameter such as the ultrasonic pulse velocity. Among the numerous correlations proposed to limit the uncertainty of this method, three of the most reliable are usually taken into account. The aim of this study is to verify the accuracy of these formulas. To this end a number of Destructive Tests (DTs) and Non Destructive tests (NDTs) have been performed on some existing concrete structures. The above relationships have been assessed comparing NDT results to compressive strengths of core drilled in adjacent locations.noneLucio Nobile; Mario Bonagura; Mario NobileLucio Nobile; Mario Bonagura; Mario Nobil