Rehabilitation Design of Jointed Plain Concrete Pavement

Unbonded jointed plain concrete (JPC) overlay is a viable rehabilitation technique for distressed jointed plain concrete pavement (JPCP). The design of unbonded JPC overlays requires performing minimal repairs to the existing JPCP, placement of an asphalt separator layer between the existing portland cement concrete (PCC) layer and the overlay design (determination of overlay PCC thickness), and placement of the overlay. Concrete overlay thickness typically is determined with mechanistic-based design procedures that require a knowledge of existing pavement layer types, thicknesses, and moduli. The existing PCC thickness and elastic modulus can be determined easily through coring and laboratory testing or nondestructive testing by using the falling weight deflectometer. However, establishing an appropriate PCC elastic modulus value that represents the existing damaged pavement is more challenging because coring and deflection testing typically are done on intact (uncracked or deteriorated) PCC material obtained from the sections of the existing JPCP that is in relatively good condition. Therefore, PCC elastic moduli estimated from these sources are not representative of the entire JPCP condition. Various empirical rigid pavement design procedures have been developed for adjusting intact PCC elastic modulus values into a more appropriate damaged PCC elastic modulus for JPCP overlay design. Analysis done to characterize the elastic modulus of damaged, cracked, or shattered PCC slabs based on backcalculated PCC elastic modulus and existing JPCP condition is described.