Nonlinear dynamics of asphalt–screed interaction during compaction: Application to improving paving density

Abstract

Paving compaction is one of the important steps in pavement construction that significantly affects the subsequent roller compaction and the quality of asphalt pavement, which is influenced by several factors related to the paver response and the properties of asphalt mixture. Therefore, it is necessary to relate the dynamic response of screed-asphalt mixture interaction to the change of paving density during asphalt pavement compaction in order to improving paving density throughout the pavement. In this paper, a non-linear dynamical model describing the interaction between the vibratory screed and the asphalt pavement was present to simulate the screed vibration response, the force transmitted to the paving layer (contact force) and the vibration force transmission ratio. Based on the dynamical equations for the coupled system, a mathematical model of trend density to paving density in field was developed with the inputs of asphalt mixture properties, excitation frequency and other mechanical properties of the paver screed. In contrast to traditional analyses, a combination of the response amplitude factor β(ω) representing the magnitude of the screed amplitude and the force transmitting ratio H(ω) representing the ratio of contact force to excitation force was considered in the trend density model. Moreover, the model parameters including the initial density P0 and compaction capacity coefficient P1, which were dependent on the screed specifications and the material properties of the asphalt mixture were calculated using the common and simple lsqcurvefit algorithm, and the simulation model was verified by experiments. Results show that the asphalt mixture with large limit displacement needs further compaction in a relatively low frequency, which can ensure the compaction effort while improving the force transmitting ratio. Further compaction of the asphalt mixture with a small limit displacement comes at the cost of the energy transferred to the paving mat, and the screed has serious vibration. The results also indicate that the excitation frequency higher than the resonance frequency can ensure compaction efficient, while the compaction would be made more efficient and the energy efficiency significantly increases by lowering excitation frequency.