Screed assembly for road paving machines, and a method for repaving road surfaces

Abstract

A new and improved method and apparatus for use in conjunction with the free floating paving screed used for road paving is disclosed. The method of forming a bituminous mixture into a smooth flat paved mat comprising some areas with a given nominal mat density and some selected areas with a predeterminedly higher mat density is described wherein problems posed by a reduced compaction ratio occurring subsequently to paving the mat where the roller drum bridges over recesses in the subbase are addressed. The modified paving screed described employs a new adjustable screed plate that allows localized areas of increased angle of attack and a device to increased material entry density in localized areas in front of a screed plate leading edge. Either method is used to create an increase in mat density in the desired area. The method and apparatus teach that by pairing differences in compaction ratio that inherently occur due to subbase irregularities with correspondingly predetermined and different mat densities in the paved mat, a good consistent final density can be achieved notwithstanding the limitations of the compaction rolling. A forward looking vision system is described that identifies subbase recesses, a digital controller quantifies the density increase required, and a GPS system maps locations where the mat density increases are to be applied.