Characterizing strength and thermal properties of concrete for implementation of pavement mechanistic-empirical design in New Mexico

The format of the design and performance prediction of rigid pavements was reformed with the advent of Pavement mechanistic-empirical (ME) design procedure, which now serves as the state-of-the-art tool in pavement design. Various state agencies have either completed or in the process of calibration of distress prediction models and characterization of concrete materials to provide accurate inputs required by Pavement ME design software. There are numerous concrete properties for which input data is required in ME design software, but with previous research, it was found that the concrete strength and thermal properties including elastic modulus, modulus of rupture and coefficient of thermal expansion (CTE) are the most important ones that affect the design and performance of rigid pavements. Accurate rigid pavement design is heavily dependent on accuracy of these material inputs. This study is part of a New Mexico Department of Transportation (NMDOT) research project that focuses on the development of guidelines for characterizing Portland cement concrete (PCC) materials for paving mixes being used in New Mexico. Concrete mixes with 5 different coarse aggregates were tested for these pivotal concrete properties at the curing age of 7, 14, 28 and 90 days, and for CTE at 28 days. The laboratory test results represent level 1 PCC material inputs. The data collected offered an excellent opportunity to validate and refine the ME default level 2 models for estimating flexural strength and elastic modulus based on compressive strength data. The data demonstrated a slight deviation from the nationally calibrated models. CTE values of concrete based on aggregate type were established for these paving mixes. Further analysis verified the benefit of using the level 1 inputs over the default level 3 inputs for accurate pavement design and performance prediction. It was also highlighted that transverse cracking is the most significantly affected performance parameter between the pavement designed with level 1 and level 3 material inputs.