Title:
Multi-Decade, Multi-Scale Modeling of Aging Basic Creep of Concrete
Author(s):
Brock D. Hedegaard
Publication:
Materials Journal
Volume:
117
Issue:
6
Appears on pages(s):
17-27
Keywords:
creep; dissolution precipitation; hydration; multi-scale modeling
DOI:
10.14359/51728121
Date:
11/1/2020
Abstract:
This study presents a multi-scale model for predicting multidecade basic creep of concrete. Aging of cement is modeled through hydration, densification, and polymerization of the calcium-
silicate-hydrate (C-S-H) phases. The model accounts for the separate mechanisms of viscoelastic compliance and aging viscous flow of the C-S-H, and for the dissolution-precipitation of elastic and viscoelastic phases during hydration that causes apparent creep in the composite. Upscaling is performed in the time-domain simultaneously for all loading ages. The results show that short-term
viscoelastic compliance observed from nanoindentation tests dominates short-term creep, but cannot explain long-term creep rates observed in macroscopic concrete creep tests. Such observations can only be replicated by considering viscous flow that
develops over time scales unobservable by minutes-long tests on the microscale. Dissolution creep may explain some irreversible basic creep at very early ages but rapidly diminishes in relevance as the concrete continues to age.