A discrete element simulation study of paver screed and hot mix asphalt interaction

Paving hot mix asphalt (HMA) using an asphalt paver is a complex process requiring precise adjustments of compaction units such as the tamper and vibration unit to suit varying conditions. Despite decades of advancements, the process remains largely dependent on operator experience, and scientifically validated guidelines for optimizing key parameters like tamper and vibration frequency, as well as paving speed, are lacking. Field tests are costly and limited in scope, while internal material movements during compaction are difficult to observe. This study addresses these challenges by employing a full-scale simulation using a calibrated Discrete Element Method (DEM) model to analyze HMA's flow and pre-compaction behavior. Key findings include insights into the flow and distribution of asphalt material within the auger tunnel and under the screed. The study reveals that the tamper's compaction force is primarily directed toward the chamfer and has a significant depth effect, achieving considerable pre-compaction of the material. The paving process generates distinct force distributions and particle rearrangements, with key zones of high wear impact identified, especially on the tamper chamfer. Pre-compaction due to the screed's dead weight is limited, highlighting the tamper's critical role in achieving optimal compaction. These insights suggest improvements for future paver design, including potential modifications to the screed's geometry and the introduction of heating elements on the screed front wall to reduce the risk of material cooling and ensure more homogeneous paving. This research contributes to enhancing the understanding of machine-material interactions during asphalt paving, offering practical recommendations for improving paving efficiency and longevity of road surfaces.