Contact Forces in Non-bonded Pavement Materials

ABSTRACT We have studied macroscopic stress distributions in horizontal and vertical directions in non-bonded aggregates, as well as the contact forces (local stresses) at the contact areas ("microscopic"). A ring chamber was used to study the horizontal and vertical stresses under static vertical loads, whereas contact area stresses were measured using pressure film placed in different parts of the equipment. The pressure films reveal elevated contact forces at some contact areas in response to the applied load, and the grain size range of the particles also influences the stress (contact force) distribution: fine-grained aggregates distribute forces more evenly than coarse-grained aggregates. When an open fraction of aggregates is used, the coarse-grained aggregates have a greater role in supporting loads, as higher contact forces are transmitted across contact areas between large aggregate particles. KEYWORDS: AggregateStress DistributionNon-Bonded MaterialsRoadRing ChamberPressure Film