Controlling method of segregation for coarse asphalt mixture

The segregation characteristics of coarse asphalt mixture were studied, AC-25C was taken as research object, the controlling principle of segregation was analyzed from the aspects of aggregate selection, material transfer, the operating parameters of paver's distribution room and paving pattern, and a controlling method of segregation was proposed.Study result indicates that for AC-25C asphalt mixture, some qualified aggregates from the specifications of S8, S9, S12, S14(S15) and S16 should be chosen.Contrasted with the conventional construction technology, the transverse temperature variable coefficient's extreme value of paving working face decreases from 4.39% to 1.06%, the mass pass rate variable coefficient's extreme value of aggregate passing every sieve size at the different positions of pavement transect decreases from 14.65% to 7.59%, the transverse density variable coefficient's extreme value of surface course reduces from 3.23% to 1.14%, the extreme value of texture transverse depth decreases from 28.14% to 13.79%, and the transverse permeability coefficient's extreme value of pavement reduces from 89.45% to 54.54%.In order to reduce the occurrence of segregation, when distribution room's thread pitch and rotate speed are fixed, the distance between material and axis should be no less 0.75 times of thread pitch.When distribution room's rotate speed and the distance between material and axis are fixed, distribution room's thread pitch should be about 1.3 times of the distance between material and axis.Narrow-size paving is an important way of maintaining uniform pavement.