AASHTO PP 84-20 (2021) PDF Download

AASHTO PP 84-20 (2021) is a standard practice that focuses on developing performance engineered concrete pavement mixtures. In the past, specifications for concrete pavement mixtures were prescriptive, with State Highway Agencies (SHA) dictating specific materials and proportioning requirements. However, this approach limited innovation and placed the performance risk on the SHA.

The standard recognizes the industry's advancements, such as blending cementitious materials, reducing paste content, and using additives and admixtures, which provide opportunities to specify the performance characteristics of concrete mixtures. It promotes the use of alternative performance measures for acceptance, allowing contractors to design mixtures that meet specific performance requirements.

Section 6 of the practice respects the SHA's traditional prescriptive methods while offering options to use one or more performance measures instead. The standard aims to provide SHAs with flexibility in their approach to the use of alternative performance measures, offering a range of choices that fit their specific needs.

Reducing material and construction variability is crucial for reducing the life cycle cost of concrete pavements and extending their service life. This is achieved through a robust quality control (QC) program. The standard emphasizes the importance of QC when performance-based measures are employed, as compliance with acceptance criteria depends on a well-designed and executed QC program covering process, production, and construction control.

Though the standard includes performance values based on an average concrete pavement life of approximately 30 years, it acknowledges the presence of risk due to material and testing variability as well as contractor expertise. As service life prediction models and test methods advance, the standard expects the reduction of such risks.