ABSTRACT

Stiffness is used as the principal parameter for designing pavements with the ability of the pavement to spread the load being proportional to both the stiffness and the depth, so that the thickness can be reduced as the stiffness is increased. This relationship led to a ‘great Pascal race’, in the United Kingdom, in which everybody was trying to save money by maximising the stiffness. However, this approach to pavement design risks premature failure if the stiffness is not up to the design value when constructed or if there is any loss of strength for any reason. In general, the stiffness will be expected to increase with time from binder hardening, but the stiffness can be significantly and adversely affected by high moisture susceptibility or other weathering effects.