The california department of transportation (caltrans) is currently using the portland cement concrete pavement (pccp) rehabilitation technique of cracking and seating (c&s) before placement of an asphalt concrete (ac) pavement overlay to prevent or retard reflection cracking from the underlying pccp. Field measurements of differential vertical slab deflections and ac overlay performance are compared for various c&s projects. Construction techniques, specifications, pavement breaking equipment, and cracking patterns are discussed, along with problem areas and solutions. An experimental procedure for seating broken slabs is also described. Ac overlay performance data are presented for various projects constructed with and without c&s of pccp, with variable overlay thicknesses and with and without pavement reinforcing fabric (prf). It is concluded that the c&s strategy is beneficial in preventing and retarding reflection cracking in ac overlays on pccp by reducing thermal movements of existing pccp, restoring slab support, and reducing differential vertical deflections of pccp slabs. These ac overlays, with a few exceptions, are providing excellent performance after 5 to 7 years of service. This paper appears in transportation research record no. 1307, Pavement analysis, design, rehabilitation, and environmental factors 1991.
Abstract