Performance Engineered Concrete Mixtures: Implementation at an Interstate Rigid Pavement Project

Performance engineered concrete mixtures (PEM) include optimized mixture designs which, paired with advanced quality assurance methods, provide substantially improved durability, economy, and sustainability. One agency challenge to implementation of PEM has been engagement of contractors and other industry stakeholders in field deployment. In this case, an agency, North Carolina Department of Transportation (NCDOT), US, found a willing contractor partner to support an initial concrete paving PEM implementation project. The collaborative effort supported both agency PEM implementation initiatives and provided benefits to the contractor. PEM tests included the Box Test, Super Air Meter (SAM), and surface resistivity, as "shadow tests." The contractor found the Box Test useful for mixture development and evaluation of modifications during the project. The SAM and resistivity meter were readily implemented into standard quality control (QC) testing without additional QC staff. SAM tests were performed over the course of the project, but the data was variable, and additional training is needed to support improved results. Surface resistivity test results indicated the contractor improved concrete consistency over the two project phases, and the concrete should provide good durability performance. The contractor intends to implement PEM tests for QC on future projects to help improve pavement quality. The agency found surface resistivity tests for acceptance easy to perform. For mixtures containing fly ash, research is needed to identify a 28-day surface resistivity target that generally correlates to a 56-day or 90-day resistivity that predicts good durability performance. This experience reinforced that collaboration between agency, industry, and academia will support advancement of PEM initiatives.