In the State of Texas, dry-land longitudinal cracking on the Farm-to-Market (FM) network is one of the most prevalent pavement distresses caused bythe volumetric change of expansive subgrade soils. Geogrid reinforcement and lime treatment are found to be the most effective methods to control dry-land cracks. To provide a safer and more conservative approach for the pavement structure over expansive subgrade, it is desirable to combine thetwo methods to be more effective in controlling the dry-land cracks. Thispaper appropriately integrates geogrid and lime so that both methods can contribute to the prevention of longitudinal cracks due to the shrinkage of expansive subgrade. Finite element modeling shows that the best place toinstall the geogrid should be at the interface of the lime-treated layer and the untreated soil, which is close to the initiation location of shrinkage cracks. At this location, the geogrid can effectively reduce the stress concentration at the upper crack tip. Geogrid with higher stiffness provides more benefit. Lime treatment can improve the tensile strength and fracture toughness of the expansive soil, which further reduces the possibility of cracks propagating through the lime-treated layer. Therefore, the combination of geogrid reinforcement and lime treatment offers the most benefit for the control of dry-land longitudinal cracking. The development ofmultiple shrinkage cracks helps decrease stress concentration at the crack tips when the geogrid stiffness is at a low level. If the geogrid has anextremely high stiffness, the effect of additional shrinkage cracks is not significant.
Abstract