Microstructure and Transport Properties of Concrete.
Microstructure and Transport Properties of Concrete.
(717 K)
Garboczi, E. J.
RILEM. Performance Criteria for Concrete Durability.
Proceedings. State of the Art Report prepared by RILEM
Technical Committee TC 116-PCD, Performance of Concrete
as a Criterion of Its Durability. RILEM Report 12.
Chapter 8. 1995, E & FN SPON, London,England, Kropp,
J.; Hilsdorf, H. K., Editor(s)(s), 198-212 pp, 1995.
Keywords:
concretes; transport properties; cements; mortar; sand
Abstract:
Concrete is a composite material whose microstructure is
random over a wide range of length scales. At the
largest length scale, concrete can be considered to be a
mortar-rock composite, where the randomness in the
structure is on the order of centimeters, the size of a
typical coarse aggregate. Mortar itself can be
considered to be a cement paste-sand composite, with
random structure on the order of millimeters. Cement
paste can also be considered to be a random composite
material, made up of unreacted cement, CSH, CH,
capillary pores, and other chemical phases. The
randomness in the cement paste microstructure is on the
order of micrometers. Finally, CSH is itself a complex
material, with random structure, as seen by neutron
scattering, on the order of nanometers. This range of
random structure, from nanometers (CSH) to centimeters
(concrete) covers seven orders of magnitude in size! It
is a large and difficult task to try to relate
microstructure and properties theoretically for
concrete. However, there are some simple, basic ideas
that do provide a framework for this task, with the main
difficulty being carrying these ideas through to
specific application. This chapter attempts to outline
the general principles that must be considered in trying
to understand microstructure transport property
relationships in concrete, or indeed any other random
porous material. Specific applications to cement paste,
mortar, and concrete will be considered. An earlier
review, which mentions some of the ideas discussed in
this chapter is also a helpful reference for some of the
earlier transport property data and their interpretation
in terms of pore structure.
