Pavement preservation is an important activity for state departments of transportation (DOTs) in maintaining and enhancing their highways. With the 2012 enactment of the Moving Ahead for Progress in the 21st Century Act (MAP 21) wherein DOTs must monitor the performance of their highways, the use of pavement preservation treatments is critical to meet pavement performance goals. Pavement preservation treatments do not improve the structural capacity of a pavement but do delay pavement deterioration.
Cold central plant recycling (CCPR) and cold in-place recycling (CIR) are two commonly used rehabilitation/pavement preservation treatments. CCPR and CIR treat higher severity distresses than other preservation techniques. Both techniques require topping the recycled layer with a surface treatment to produce a longer lasting pavement. CCPR and CIR treatments are part of a sustainable strategy for reducing the need for virgin aggregate and asphalt binder while using lower energy and creating fewer emissions.
AASHTO is a standard-setting body that publishes specifications, test protocols and guidelines used in highway design and construction throughout the United States. AASHTO standard specifications for pavement preservation treatments are intended to provide credibility, and more importantly, buy-in from specifying agencies. In order to implement any of these treatments in construction projects, material and construction standards must be created first. The AASHTO Committee on Materials and Pavements (COMP) has already established provisional standards for CCPR and CIR materials and mix design practice. However, as noted in NCHRP Synthesis 421: Recycling and Reclamation of Asphalt Pavements Using In-Place Methods, one barrier to greater use of these treatments is lack of construction specifications. Development of construction guide specifications accounting for the best practices of specifying agencies and contractors will greatly assist in increasing the use of these treatments, especially by agencies with little experience with CCPR and CIR.
The objective of this research was to produce proposed AASHTO Construction Guide Specifications for the application of CCPR and CIR in the standard five-part AASHTO format with supporting commentary. The specifications shall include plans for quality assurance and agree with current provisional material specifications and mix design practices for these treatments. The specifications shall enable specifying agencies to tailor their own specifications to the local conditions and environments.