The loading frequency is an important input for determining the stiffness of asphalt materials on the basis of their dynamic modulus data. This stiffness relationship is used in the Mechanistic–Empirical Pavement Design Guide (MEPDG) to calculate a pavement's structural response to loading. This response—typically maximum horizontal strain and vertical pressure—is then used to estimate the number of load repetitions to failure. The Marquette Interchange Perpetual Pavement Instrumentation Project is a research effort carried out by the Transportation Research Center at Marquette University. The project implemented different pavement sensors to provide researchers with a complete set of pavement response data for calibration of local design variables and to provide insight into the structural behavior of a perpetual pavement opened to live urban freeway traffic. An analysis of the strain and pressure data recorded from the project was conducted to measure the length of strain and pressure pulse durations. The load pulse durations for each axle were then analyzed and compared with models contained in the MEPDG software. The analysis showed that the models may broadly fit actual load durations, but the surrounding assumptions may not be adequate for all axle and load configurations.

Techniques are presented that are based on the dense-liquid foundation model for analyzing deflection data obtained at center slab, slab edge, and slab corner positions to provide indications of the quality and uniformity of support beneath jointed concrete slabs. Deflections obtained at central slab positions are used to quantify a baseline foundation k-value for each slab tested. Edge and corner deflection data are used to establish the foundation edge and corner k-values of each slab. Adjustments for slab size and temperature curling during testing are discussed. Slab support ratios are determined on a slab-by-slab basis using the ratio of edge and corner k-values to center-of-slab k-values, ke/ki, and ke/ki. When nonuniform support exists, the foundation support ratio will typically be less than 0.75. Example and field results are provided to illustrate the analysis techniques and the interpretations necessary to distinguish between poor support due to slab curling or foundation voids.

Cold in-place recycling (CIR) is a common rehabilitation practice used in Wisconsin to improve the ride quality and structural capacity of deteriorated asphalt pavements. In recent years, increased emphasis has been placed on incorporating stabilizers into the CIR materials to improve the structural capacity of the CIR base layer. This improvement can serve to increase the performance life of the completed pavement or to allow for a reduced hot-mix asphalt (HMA) surface thickness. The city of Mequon, Wisconsin, included asphalt emulsion and fly ash CIR stabilization over a portion of its CIR projects in 1997. Presented are the findings relating to the constructability of the fly ash–stabilized CIR pavement as well as performance trends for the CIR pavements based on distress and deflection testing results. CIR is a common rehabilitation practice used in Wisconsin to improve the ride quality and structural capacity of deteriorated asphalt pavements. In one type of CIR application, existing HMA layers are pulverized, graded, and compacted, then used as a base layer for a new HMA surface. The pulverization process is completed to provide uniformity of support to the HMA surface and to significantly reduce or eliminate the occurrence of reflection cracking of the HMA surface. In most CIR applications, pulverization is completed through the full thickness of the existing HMA layers, as well as through the top 25 to 50 mm of aggregate base. Penetration into unbound aggregate base materials aids in cooling of the bits on the pulverizer mandrel. After pulverization, graders typically are used to spread the materials to the desired width and shape. Compaction is achieved by using vibrating steel drum and pneumatic-tire rollers. The moisture content of the CIR materials is adjusted, as necessary, by surface spraying from a water tanker truck.

The evaluation of support conditions under jointed concrete pavement slabs is an important input into pavement analyses. Closed-form solutions are available to determine support conditions under the central portion of the slab; however, these solutions assume interior loading (infinite slab) and slab-on-grade conditions.This paper provides corrections necessary to extend these solutions to finite slab sizes.Also provided are closed form solutions for determining foundation support conditions under slab edges and corners using deflection measurements obtained at these locations.

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