Volume Change Behaviour of Engineered Lacustrine Clay Fill: Applications in Construction and Design of Highway Embankments

ABSTRACT: Early pavement distress was identified after the completion of an asphalt paving project in Southern Manitoba along Provincial Trunk Highway 59, which was founded on a high plasticity clay fill embankment. These observations prompted several studies to investigate potential geotechnical mechanisms leading to the observed cracking. The mechanisms that were considered included both the swelling of the clay subgrade and differential frost action. This was assessed in a study by MTI and KGS Group that monitored instrumentation between 2007 and 2015. Recently, representative embankment subgrade fill was sampled and laboratory testing was completed for the purpose of confirming soil behavior parameters and assessing the swell potential in a laboratory setting. Laboratory testing has been undertaken to evaluate the volume change behaviour of clay at compacted moisture contents both wet and dry of the optimum moisture content. The in-situ monitoring, laboratory testing, and some empirical calculations remain inconclusive as to what degree the swelling of the clay subgrades were affecting the pavement performance. The development of a simplified numerical model using parameters derived both in the laboratory setting and in the field is presented in order to comment on the observed behavior of the embankment and the possible geotechnical mechanisms causing the pavement distress.