NANOSCALE STRUCTURE AS THE BASIS FOR FUNDAMENTAL MODELS OF CONCRETE DURABILITY
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 controllcd 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) andrelated pores are the most important. This phase forms the backbone of portland cement-basedconcretes, and deterioration occurs by chemical change and/or stress such as that introducedby crystallization (salts and ice) in the pores. Nanogranular models of cement paste havealready been used to quantitatively predict some relatively simple properties such as elasticmodulus 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 long-term properties of concrete.
H.M.Jennings J.J.Thomas I.Vlahinic J.J.Chen
Civil and Environmental Engineering,Northwestern University,USA;Materials Science and Engineering,No Civil and Environmental Engineering,Northwestern University,USA Lafarge Centre de Recherche,St.Quentin Fallavier,France
国际会议
南京
英文
3-14
2008-10-13（万方平台首次上网日期，不代表论文的发表时间）