Modulus Effects $-$ Asphalt Layer

Consider a three layered elastic system with asphalt concrete as a top layer, aggregate base course $($ABC$)$ as the second layer, and soil as the bottom layer:

Increases in the modulus of the asphalt concrete layer will $($increase$/$decrease$)$ the vertical stress on top of the subgrade. This increase$/$decrease is a

$($weak$/$strong$)$ function of the increase in modulus.