ABSTRACT
In the case of a pavement with concrete slabs, faulting of two consecutive slabs can be measured with the Faultimeter. This instrument fixed on a tripod and placed across a joint, measures the maximal relative movement B of the adjacent slabs while the 11 tons rear axle of a truck slowly passes by. Movement B is the sum of maximum B1 observed for the oncoming axle and maximum B2 observed when the axle moves on the slab behind the joint. The Falling Weight Deflectometer (FWD) is also used for the analysis of load transfer efficiency (LTE) over joints and for void detection under a slab. Results of studies at BRRC about the use of these devices for the evaluation of the stability of concrete slab pavements were published previously. In particular when comparing the results of these devices, it was noticed that sometimes the FWD identified low LTE where the Faultimeter indicated small relative slab movements. In that respect, FWD and Faultimeter are complementary.
However, these previous studies did not consider the time-history data collected by the FWD. In this contribution we report on further investigations where we do include the FWD time-history data. We will present new gained insights on the interpretation of the FWD data and how they compare to the Faultimeter data. A displacement observed by the geophones of the FWD when the charge is dropped on the slab after the joint correlates well to B2. A similar correlation can be established for the displacement observed by the geophones of the FWD when the charge is dropped on the slab before the joint and B1, except in cases where the LTE is extremely low. This observation and its consequences for the evaluation of faulting will be elaborated in the paper.
