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Title: Coupled Pore Relative Humidity Model for Concrete Shrinkage and Creep

Author(s): Brock D. Hedegaard, Timothy J. Clement, and Mija H. Hubler

Publication: Materials Journal

Volume: 120

Issue: 3

Appears on pages(s): 103-116

Keywords: creep; shrinkage; time-dependent behavior

DOI: 10.14359/51738709

Date: 5/1/2023

A new semi-empirical concrete shrinkage and creep model called the CPRH Model is proposed and calibrated. The new model proposes a coupling between autogenous and drying shrinkage using a volume-average pore relative humidity and treats drying creep as an additional stress-dependent shrinkage, linking together all these phenomena. The proposed expressions are designed to facilitate traditional integral-type analysis, but also uniquely support ratetype calculations that can be leveraged by analysis software. Model calibration uses the Northwestern University (NU) database of creep and shrinkage tests to determine new model parameters. The proposed model uses minimal inputs that are often known or may be assumed by the design engineer. Comparison of the proposed model to historical time-dependent models indicates that the new model provides a superior fit over a wider range of inputs.