Influence of Pre-Overlay Pavement Condition on Service Life and Cost-Effectiveness of Stone Matrix and Hot Mix Asphalt Overlays for Preventive Maintenance

Timely and appropriate pavement maintenance is essential for extending service life and minimizing long-term costs. Achieving these outcomes requires reliable performance models to evaluate treatment effectiveness. Pre-overlay conditions affect asphalt overlay performance, so including them in modeling is important for cost-effective selection. This study evaluates and compares the performance and cost-effectiveness of stone matrix asphalt (SMA) and hot mix asphalt (HMA) overlays in Indiana, U.S., using the International Roughness Index (IRI) as a deterioration indicator to estimate service life. A central focus is the influence of pre-overlay conditions on service life and economic viability. Both deterministic and probabilistic life cycle cost analysis (LCCA) are employed: the former uses fixed input parameters, while the latter accounts for uncertainty in performance, costs, and discount rates through Bayesian inference and Markov chain Monte Carlo simulation. The results indicate that HMA overlays deteriorate significantly faster than SMA overlays. Additionally, SMA performance is more sensitive to pre-overlay IRI levels. Despite higher unit costs, SMA is more cost-effective over the evaluation period, yielding a slight (2.08%) saving over HMA. An IRI threshold of approximately 111 in./mi was identified where the life cycle costs of SMA and HMA converge. Below this threshold, SMA is more cost-effective; above it, HMA becomes the more economical option for severely deteriorated pavements. Although the cost difference is small below the threshold, it becomes increasingly pronounced as pavement deteriorates. Probabilistic LCCA revealed substantial variability in outcomes, with equivalent uniform annual cost uncertainty increasing with pre-overlay IRI, particularly for SMA, which indicates elevated financial risk when applied to poorly maintained pavements.