Description

This postdoctoral research opportunity at the National Institute of Standards and Technology (NIST) focuses on advancing the measurement science of concrete rheology. Concrete, composed mainly of cement paste and aggregates, currently relies on semi-empirical methods (e.g., slump cone tests) to assess flow properties. This project aims to replace these with scientifically grounded tools, combining experimental techniques and multiscale simulations.

NIST's approach models cement paste as the fluid phase for mortar, which in turn forms the medium for concrete. Understanding cement paste behavior feeds into computerized simulations predicting concrete's rheological properties. NIST has developed tools such as Standard Reference Materials (SRMs) for calibrating rotational rheometers and a grout pumping station for validating predictions.

The project includes improving predictions of concrete flowability in pipes, placement, and finishability. It also involves developing new test methods for measuring rheological properties on-site or in the lab, useful for quality control or model validation. These methods may be proposed for adoption as ASTM standards.

Key References

• Ferraris CF, Martys NS: Concrete Rheometers, in Understanding the Rheology of Concrete, Woodhead Publishing, 2012.
• Ferraris CF, et al: Development of Reference Material for Cement Paste Rheometer Calibration, ASTM Advances in Civil Engineering Materials, 2013.
• Martys NS, et al: Rheologica Acta, 2010.