Abstract

With the continuous limitations in budgets for pavement preservation and maintenance, Nevada road agencies expressed interest in learning about the performance of cape seal treatments with either a slurry seal or a micro surfacing, and their abilities to extend pavement life at the least cost. Accordingly, this study evaluated the long-term performance of cape seals that have been constructed in Northern Nevada during the past 15 years. Among the six factors that were evaluated (construction, materials, traffic, structure, environment, and pre-PCI), only the pre-PCI value (i.e., PCI value prior to the application of cape seal) had a significant impact on the long-term performance of the cape seals. Micro surfacing cape seals exhibited very consistent long-term performance regardless of the conditions of the existing pavement as expressed by the pre-PCI level. This was shown by the narrow range of the final PCI values of all micro surfacing cape seals of 70-80. The effective performance life of micro surfacing cape seals ranged from 5 years in Incline Village (base elevation of 6,350 feet) to 7 years in the Truckee Meadows (base elevation of 4,400 feet). On the other hand, the effective performance life of slurry seal cape seals was 3.0 and 3.5 years in the Incline Village and Truckee Meadows, respectively. The LCCA indicated that the micro surfacing cape seal is more cost effective than the slurry seal cape seal. Based on the excellent long-term performance and the significantly higher benefit-cost ratio of the micro surfacing cape seals as compared to the slurry seal cape seals, it was recommended to continue the use of the micro surfacing cape seal as a preventive maintenance treatment.

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