Evaluation of Grouting Condition of Post-Tensioned Concrete using R-wave Method

Abstract

Post-tensioning (PT) system is widely used not only in bridge construction, but also used as a replacement of reinforced concrete (RC) structure for slab, beam, and wall. Nowadays, many countries around the world are focusing on sustainable development in the construction industry. PT system is one of a system which able to meet the standard of sustainable building construction. Its advantages are able to save more materials, construction time and maintenance cost. To ensure the safety of PT systems during construction, some methods are implemented to evaluate the concrete condition. In this study, the Rayleigh wave (R-wave) method is used to evaluate the grouting condition of the post-tensioned concrete structure. Useful parameters of R-wave such as amplitude, time, frequency and wave velocity are identified and obtained through a series of numerical simulations and experimental tests. Different frequencies are excited to examine the behavior of R-wave propagated through a concrete medium with different grouting conditions in the simulation. In experimental testing, different diameters of steel balls are used as an impactor to generate waveform and the generated waveforms were recorded by the data logger. Three equidistance receivers are placed on top of the tested concrete specimen with different duct materials of aluminium duct and PVC duct embedded in it. As a conclusion, when voids are present in the concrete specimen, high readings of amplitude and dominant frequency are recorded and the travelling wave velocity is slow.