Performance and Failure Modes of Louisiana Asphalt Pavements with Soil-Cement Bases Under Full-Scale Accelerated Loading

Abstract

The performance and failure modes of conventional soil-cement base asphalt pavements and alternative pavements have been investigated under accelerated loading. Surface cracking was evaluated in terms both of the crack rate (in meters per square meter) and the AASHTO Class 1, 2, and 3 classifications. Pavement structural capacity was evaluated in terms of falling weight deflectometer (FWD) deflection-based back-calculated moduli of asphalt layer and soil-cement bases. Analysis showed that there was no significant difference in pavement performance among the soil-cement base pavements, although the cement content, strength, and construction procedures for the soil-cement bases were different. A significant improvement in pavement fatigue life was found for the “inverted” pavement structure, in which a stone crack relief layer was placed between the soil-cement base and the asphalt surfacing. The fatigue life of the inverted pavement was five to six times longer than that of pavements without the stone layer. Different failure modes were found between the inverted pavement and the others, and the corresponding failure mechanisms were analyzed on the basis of the observations from the pavement postmortem, when loading was terminated. Analysis of the FWD deflection data indicated that under accelerated loading there was a significant decrease in asphalt and soil-cement moduli for the inverted pavement, although the same trend was not observed on the other soil-cement bases. The crack data were used to evaluate two pavement fatigue life prediction models. It was found that the current models are not applicable to the soil-cement base pavement with a stone crack relief layer.