Title: Predicting the Microstructure Stabilization Time from Electrical Resistivity Measurements

Author(s): Thomas Bernard and William Wilson

Publication: Symposium Paper

Volume: 362

Issue:

Appears on pages(s): 453-460

Keywords: bulk electrical resistivity, durability, Fick’s second law, hyperbolic law, microstructure stabilization time

DOI: 10.14359/51741002

Date: 6/14/2024

Abstract:
There is no accepted test to determine the time needed for a cement paste microstructure to stabilize (and thus, for its diffusion coefficient to stabilize). This stabilization time is crucial when applying Crank's solution to Fick's law of diffusion of deleterious ions, as an important hypothesis is a constant diffusion coefficient. One potential approach involves utilizing the hyperbolic law to fit the evolution of bulk electrical resistivity, which is directly related to microstructural changes. This approach could provide a rapid means of determining the stabilization time and the final resistivity value. The objective of this work is to validate if this law is appliable for different types of cement and different types of curing and to determine the stabilization time for the different types of cement pastes: Ordinary Portland Cement (OPC) and blends with Supplementary Cementitious Materials (SCMs, i.e., slag, fly ash, silica fume, and limestone). Results show that the hyperbolic law for Portland cement allows predicting in 56 days the resistivity after 120 days with an error of less than 1%. Moreover, this law can be useful to estimate the time necessary for stabilization of the resistivity. However, it appears that this law is not applicable to every type of SCM especially silica fume and fly ash.