A true mechanistic pavement design procedure should be able to correctly predict pavement response and the development of pavement distress (such as rutting and fatigue cracking) under various traffic and environmental conditions. A three-dimensional (3-D) numerical simulation procedure with realistic material models would be an effective tool that could be used to achieve such an objective. The results of a 3-D numerical simulation at the Louisiana Accelerated Loading Facility are presented. A 3-D finite-element procedure with moving wheel loads was developed for such analyses. Rate-dependent viscoplastic models were incorporated into the 3-D finite-element procedure. A creep model was used to predict rutting of the asphalt pavement. The results indicated that the 3-D finite-element procedure with viscoplastic models is capable of reflecting the pavement responses and predicting pavement rutting with reasonable accuracy.

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Pavement performance is related to resilient modulus and permanent deformation properties of pavement materials, as well as other factors such as environmental and traffic conditions. Current resilient modulus test procedures and correlations do not fully describe permanent deformation properties. This limitation signifies the need for a permanent deformation test procedure for proper material characterization. The objective of this study was to evaluate resilient and permanent deformation properties of seven base materials with a proposed permanent deformation test that can provide both resilient modulus and permanent deformation properties. The base materials used were obtained from test sections recently constructed at the Louisiana Pavement Research Facility. These included crushed limestone, blended calcium sulfate, blended calcium sulfate treated with slag, blended calcium sulfate treated with fly ash, recycled asphalt pavement, foamed asphalt–treated 100% recycled asphalt pavement, and foamed asphalt–treated blend of 50% recycled asphalt pavement and 50% soil cement. Laboratory repeated load triaxial permanent deformation and material property tests were performed on these materials. A power model that correlated the accumulated permanent strain to the number of repeated load cycles for each material considered was developed. A good correlation between resilient moduli and permanent strains was observed. Blended calcium sulfate treated with slag exhibited the highest resilient modulus and the lowest permanent deformation values of the investigated materials, followed by blended calcium sulfate treated with fly ash, blended calcium sulfate, crushed limestone, and recycled asphalt pavement.

The first full-scale accelerated pavement testing experiment in Louisiana began in February 1996. The purpose was to evaluate the historically prevalent flexible crushed-stone and in-place soil cement-stabilized base construction in comparison with several alternative base construction materials and construction processes for pavements designed for a semitropical climate. More than 6 million equivalent single-axle loads (ESALs) were applied to nine test lanes in the three phases of the project. The full-scale loading was provided by an accelerated loading facility (ALF) machine, the second of its type in the United States. Surface deflection, longitudinal and transverse profiles, surface cracking, stresses and strains in the pavement structure, as well as environmental conditions were monitored during testing. The initial findings are presented in relation to rutting, roughness, cracking, layer modulus, and stress and strain evolution. In order to account for the localized deterioration of some lanes, a method based on statistical survival analysis theory was used to assess the pavement life. Reasonable agreement was observed between the life of the tested structures and the life predicted by the current procedure, on the basis of the 1993 pavement design guide from AASHTO, for the crushed-stone base pavements. The observed lives of the pavements with a soil cement base were shorter than the predicted lives.

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