TEMPERATURE CORRECTION OF FALLING WEIGHT DEFLECTOMETER DATA . THIRD INTERNATIONAL CONFERENCE ON BEARING CAPACITY OF ROADS AND AIRFIELDS. PROCEEDINGS, NORWEGIAN INSTITUTE OF TECHNOLOGY, TRONDHEIM, NORWAY, JULY 3-5 1990. VOLUMES 1-2

This paper examines several different methods of evaluating the effect of temperature on falling weight deflectometer (FWD) measurements performed on asphalt pavements in Sweden. It starts by reviewing the relevant literature, including Appendix L of the AASHTO Guide for Design of Pavement Structures (1986) (See IRRD 815401). The author's own method, used in the TEMPKORR computer program, uses the following procedure: (1) divide the road structure into layers; (2) use a backcalculation program to estimate the mean moduli of elasticity from the FWD data; (3) use a graph of the temperature dependence of the modulus of the asphalt pavement; (4) correct the FWD field measurements according to that dependence. Other methods considered: (1) determine the mean temperature of the pavement; (2) use reference temperatures; (3) correct the measured deflection; (4) correct the modulus of the asphalt. Field measurements, carried out at 6 test sites from 1987 to 1989, are summarised, and the use of the selected methods on their test data is discussed. This leads to the following recommendations: (1) find the thickness and preferably also the structure, age and crack status of the bitumen-bound layer; (2) find the mean temperature of the asphalt layer at the time of measurement; (3) perform the necessary corrections allowing for temperature. (TRRL)