Speckle techniques for pavement surface analysis

Speckle techniques are investigated for the characterization of pavement surface microtexture, particularly, height variations from one up to about ten micrometers in amplitude. Using the scalar diffraction theory of Kirchhoff, some simulations of the speckle contrast were carried out to bring out some patterns in case of a subjective speckle whose grains are not resolved by CCD photodetectors and in the case of a two-scale surface texture. We deduce the possibility of characterizing the fineness of the microtexture or its evolution versus wear modifying. The method is also experimentally applied to some reference surfaces (abrasive papers with various finenesses) and some models of pavement surfaces at various steps of wear.