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Nanoscale structure as the basis for fundamental models of concrete durability



Title: Nanoscale structure as the basis for fundamental models of concrete durability
Author(s): H.M. Jennings, J.J. Thomas, I. vlahinic, J.J. Chen
Paper category : conference
Book title: International Conference on Microstructure Related Durability of Cementitious Composites
Editor(s): W. Sun, K. van Breugel, C. Miao, G. Ye and H. Chen
Print-ISBN: 978-2-35158-065-3
e-ISBN: 978-2-35158-084-4
Publisher: RILEM Publications
Publication year: 2008
Pages: 3 - 14
Total Pages: 12
Nb references: 19
Language: English


Abstract: Understanding the mechanisms of deterioration provides a basis for developing reliable models of expected lifetimes. Properties, including viscous flow, drying shrinkage, and cohesion, are controlled by mechanisms that operate at the nanoscale, which includes solid and the smallest pores. Other properties are controlled by porosity at microscopic scales and still other properties are controlled by aggregate and reinforcing materials at macroscopic scales. The most elusive aspect of concrete is the structure and properties of the hydration products in cement paste, of which the structure of calcium silicate hydrate (C-S-H) and related pores are the most important. This phase forms the backbone of portland cement-based concretes, and deterioration occurs by chemical change and/or stress such as that introduced by crystallization (salts and ice) in the pores. Nanogranular models of cement paste have already been used to quantitatively predict some relatively simple properties such as elastic modulus with good success. The next step is to tackle increasingly complex properties such as strength, creep, shrinkage, permeability, and most importantly durability. Many of these processes can be modelled in a representative volume about 100 um cube, which captures much of the relevant physics and chemistry. This paper describes the nanogranular perspective and some of the unique advantages it brings to the problem of understanding concrete. Here we discuss how the nanoscale and the micron scale are related, and how a combined analysis at these two length scales is the key to predicting both short-term and longterm properties of concrete.


Online publication: 2009-06-09
Publication type : full_text
Public price (Euros): 0.00