Effectiveness of Lime in Hot-Mix Asphalt Pavements

Abstract

The pavement community has recognized that moisture damage of hot-mix asphalt (HMA) has been a serious problem since the early 1960s. Numerous additives have been evaluated with the objective of reducing the potential of moisture damage in HMA mixtures; lime has been one of the most common ones. The Nevada Department of Transportation has been using lime in HMA mixtures since the mid-1980s. The objective of this research was to quantify the improvements in pavement performance that have been realized through the addition of lime to HMA mixtures. The program evaluated field samples and pavement performance data from untreated and lime-treated pavements. The properties of untreated and lime-treated mixtures from field projects in the southern and northwestern parts of Nevada indicate that lime treatment of Nevada's aggregates significantly improves the moisture resistance of HMA mixtures. The study showed that lime-treated HMA mixtures become significantly more resistant to multiple freeze–thaw cycles than do the untreated mixtures. Long-term pavement performance data indicate that under similar environmental and traffic conditions, the lime-treated mixtures provide better-performing pavements with fewer requirements for maintenance and rehabilitation activities. The analysis of the impact of lime on pavement life indicates that lime treatment extends the performance life of HMA pavements by an average of 3 years. This extension represents an average increase of 38% in the expected pavement life.