Pavements, when constructed on expansive subgrades, are subjected to significant environmental loads and can fail prematurely, through the formation of longitudinal cracks. In Australia, the cover method is usually adopted to limit the adverse effects of a reactive subgrade on pavement performance. AS 2870-2011 is generally adopted as a guide for determining the cover required to limit the differential heave in pavements to tolerable limits and in doing so, it is expected that the pavements are less likely to undergo premature failure due to expansive subgrade. A recent study carried out by the authors indicates that mechanically stabilised pavements undergo less differential heave when compared to non-stabilised pavements of the same thickness and therefore are less prone to longitudinal cracking. This study aims to further the initial work undertaken by the authors, by determining the differential heave in both mechanically stabilised and non-stabilised pavements for a range of pavement thicknesses, suction depths/soil reactivities and thus quantifying the reduction in differential heave that can be achieved through mechanical stabilisation. It is expected that the outcomes of this research would give practitioners confidence in adopting mechanical stabilisation as a cost-effective way of dealing with the expansive subgrade problem rather than the conventionally adopted and more expensive cover method.