The purpose of this interagency research project with the National Institute of Standards and Technology (NIST) is to work cooperatively with the Federal Highway Administration (FHWA) on cement hydration kinetics modeling research. The focus will be on clearly defining the causes of the onset and end of the induction period of alite, which controls set, strength, and subsequent microstructural development. The researchers will simulate the presence of mineral and chemical admixtures by introducing aluminate and sulfate ions and organic retarders at ratios known to perturb normal hydration. The researchers will also use new experimental methods capable of measuring chemical and microstructural changes on the nanometer to micron scale during hydration; the goal is to use this insight to improve the ability of NIST's HydratiCA model to predict hydration kinetics and microstructure in the presence of supplementary cementing materials (SCMs), such as fly ash, slag and metakaolin, as well as in organic admixtures. This detailed understanding will also lead to the improvement of the boundary nucleation and growth (BNG) model to permit prediction of hydration kinetics and setting behavior, using a software tool that is powerful but simple enough to be used in the field.
Models of cement hydration and data for the National Institute of Standards and Technology Virtual Cement and Concrete Testing Laboratory models. [Source: FHWA, PMSS Database (2013)]