Evaluation by FWD and Faultimeter of Concrete Slabs Stability

In order to rehabilitate non-dowelled secondary concrete slab roads or to reduce noise caused by faulting slabs, it is necessary to have a clear understanding of their stability.. Faulting, pumping and the presence of voids must be investigated, and appropriate stabilization measures must be taken. Different investigation techniques are applied worldwide. In this paper, load transfer efficiency (LTE) and void detection data obtained with the Falling Weight Deflectometer (FWD) are compared with faulting data obtained with the Faultimeter. In the frame of a research project financed by the Flemish ministry, measurements were carried out with both devices simultaneously on several roads, both in the presence of voids and at more stable places. LTE results by the FWD and faulting results by the Faultimeter are consistent. This reassures us about the relevance of thresholds traditionally applied in the decision making process on stabilization prior to overlaying. We will discuss the accuracy of void detection criteria with the FWD. Weather conditions and the force applied on the slabs by the FWD influence the measurement results. We will discuss their impact on the interpretation of the measurements and on the threshold for void detection.