The degree that base pavement support influences the compactibility of an asphaltic concrete (ac) overlay was determined. As a secondary objective, the faa eastern region in-place air voids compactionstandard was compared with the faa national percent marshall density compaction standard. Field data were collected on three paving projects in faa's eastern region. Nondestructive testing (ndt) was usedto quantify the stiffness of base pavements before construction of overlay. After overlay construction, the unit weights of the asphaltoverlays were determined at the same locations at which ndts were performed, and in-place air voids and percent marshall densities werecomputed. Statistical techniques were used to investigate correlations between stiffness and ac density (i.E., Unit weight, in-place air voids, and percent marshall density). Although a mild correlation between stiffness and density was found at one project, no general trends were detected for the other projects or from regression analyses performed on combined data bases. This finding may suggest that base pavement stiffness is not a primary variable affecting overlay compaction on airport pavements; however, the effect of stiffness mayhave been masked by other external variables such as temperature, rolling, mix properties, or quality control. Finally, apparent inconsistencies in acceptable quality level and payment were observed between faa eastern region and faa national density acceptance plans. A follow-up study was initiated by faa to evaluate the basis both of eastern region and national acceptance plans for ac. Recently completed, the new study made definitive recommendations for both acceptance plans with regard to (a) acceptance requirements; (b) quality control requirements; (c) acceptance limits for air voids, stability, flow, and density; and (d) a payment adjustment plan for density. Thispaper appears in transportation research record no. 1282, Transportation construction 1990.
Abstract