Influence of Temperature on Falling Weight Deflectometer Test Results on Concrete Pavements

During intensive investigation programme carried out on 90 km of newly constructed motorway with sections of jointed plain concrete pavements (JPCP) with dowels and continuously reinforced concrete pavement (CRCP) a number of different non-destructive tests were carried out before and within first year of their operation. Among others the deflection measurements using Falling Weight Deflectometer (FWD) were carried out in order to monitor and verify design assumptions by back-calculating the elastic layer modules and determining the load transfer efficiency (LTE) on joints. The changes in the temperature gradient in the slab (curling) during measurements have had a significant influence on variability of measured deflections and so on results on analysis. In order to define this relationship some field experiments later on were carried out. FWD load plate was placed at different slab positions and the deflections were measured at the same places at every hour of the day. Temperatures at the surface and within the slab were also recorded. Tests were carried out on JPCP slabs placed on cement treated sub-base as well as aggregate sub-base and CRCP slab. Measurements were carried out by two calibrated FWD devices in order to establish reproducibility. Article describes some results of analysis of these measurements.