HIGH FINE SAND CONTENT ASPHALT MIXES REDUCE RUTTING IN ASPHALT PAVEMENTS IN MANITOBA

摘要

This paper presents findings from studies conducted on asphalt mixes placed on three of Manitoba's highest volume asphalt roads: PTH No. 100 and No. 101 (the Perimeter Highway); PTH No. 1 (the TransCanada Highway); and PTH No. 16 (the Yellowhead Highway). Rutting studies conducted by the Manitoba Department of Highways and Government Services in the mid-1980s resulted in some major changes to asphalt mixes designed to improve resistance to rutting, reduce lifetime maintenance costs, and extend the life span of Manitoba's asphalt pavements. The paper will focus on the improvements in pavement rut resistance, as this improvement is the easiest to measure. Changes made include the systematic addition of substantial amounts of clean rounded sand which the Department calls VMA Additive Sand (material passing the 425 μm sieve and retained on the 180 μm sieve) and the move to larger top size aggregate asphalt mixes. These changes produced asphalt pavements with a high resistance to rutting when subjected to lifetime loading of up to 30 million Equivalent Single Axle Loads (ESALs). An examination of factors that directly and indirectly influence an asphalt pavement's resistance to rutting revealed that conditions commonly accepted as affecting rut formation do not.