Concrete slab analyses with field-assigned non-uniform support conditions

Intelligent compaction (IC) technologies have been used to locate and identify areas of soft, weak or non-uniform subgrade support, which can be linked to pavement performance to set realistic limits on allowable non-uniformity as identified by IC. Based on field data, finite element analyses were performed to investigate the impact of non-uniformities on concrete slab tensile stresses. Non-uniform support cases were modelled by deterministically and randomly assigning field-correlated moduli of subgrade reaction (k-values) to specific spatial areas in the foundation layer. Stresses depended on the size of the non-uniform area, the stiffness change between adjacent non-uniform areas, load location and configuration, and temperature differential. Cases with randomly assigned k-values showed as much as a 39% increase in peak slab tensile stresses relative to a uniform support condition, which could lead to premature slab failures. The ability of IC to locate foundation non-uniformities could increase the reliability of concrete pavements.