A HISTORY OF DEFLECTION TESTING

The reasons for measuring pavement deflection are outlined. Since 1935, a greater understanding of the value of deflection readings has developed. Measurement methods have used either a rolling wheel or a simulated wheel load. The instrumentation used for rolling wheel deflectographs has progressed from the Benkelman deflection beam, LaCroix deflectograph, Curviameter, Road Deflection Tester, Flash Deflectograph, Rolling Wheel Deflectometer and High Speed Deflectograph. The emphasis of more recent research is to measure pavement deflections at high speed, incorporating the use of high-speed digital computers. Pseudo wheel deflection methods use either oscillating or pulse loads. The use of the falling weight deflectometer and the interpretation of the deflections is introduced. It is used for assessing the structural properties of new pavements, in-service pavements and rehabilitated pavements. For the covering abstract for this conference see ITRD E124961.