Percolation Aspects of Cement Paste and Concrete: Properties and Durability.
Percolation Aspects of Cement Paste and Concrete:
Properties and Durability.
(1234 K)
Garboczi, E. J.; Bentz, D. P.
High-Performance Concrete: Research to Practice.
American Concrete Institute Spring Convention.
Proceedings. ACI Special Publication 189. March 14-19,
1999, Chicago, IL, 147-164 pp, 1999.
Keywords:
cements; concretes; chlorides; diffusivity; durability;
materials science; microcomputers; microstructure;
percolation; permeability; simulation; transport
Abstract:
Portland cement concrete is a composite material, where
the matrix consists of portland cement paste. Cement
paste forms from the hydration reaction of portland
cement with water. The microstructure of cement paste
changes drastically over a time period of about one
week, with slower changes occurring over subsequent
weeks to months. The effect of this hydration process on
the changing microstructure can be represented using
computer simulation techniques applied to three
dimensional digitial image-based models. Percolation
theory can be used to understand the developing
microstructure of cement paste in terms of three
percolation thresholds: the set point, capillary
porosity percolation, and the percolation of the C-S-H
phase. The percolation of the interfacial transition
zones also plays an important role in concrete
microstructure, and can be dispiayed using computer
simulation models. These percolation aspects help
determinc the transport properties and therefore the
durability and service life of concrete.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899