CIRCLY 7.0 now calculates the asphalt fatigue constant (k) based on the Shell Equation – see equation 25 on page 84 of Austroads Guide to Pavement Technology: Part 2: Pavement Structural Design.
You need CIRCLY 7.0 (16 July 2020) or later.
Download the latest CIRCLY 7.0.
If you enter VB % in the VB column, k will be calculated for you.
Leave VB as 0.0 if you want to enter your own value of k.