Durability of Concrete – Degradation Phenomena Involving Detrimental Chemical Reactions Fredrik P. Glasser 1 , Jacques Marchand 2-3 and Eric Samson 3 1) Department of Chemistry, University of Aberdeen, UK 2) CRIB-Department of Civil Engineering, Laval University, Canada 3) SIMCO Technologies, Canada Abstract While interacting with its service environment, concrete often undergoes significant alterations that often have significant adverse consequences on its engineering properties. As a result, the durability of hydrated cement systems and their constituent phases has received significant attention from scientists and engineers. Cement paste deterioration by detrimental chemical reactions is discussed. First, the mechanisms that govern the transport of ions, moisture and gas are described. Then, different chemical degradation phenomena are reviewed. Microstructural alterations resulting from exposure to chlorides and carbon dioxide are discussed. Sulfate attack from external sources is described including processes resulting in the formation of ettringite and thaumasite. The mineralogy of Portland cement is sensitive to temperature and thermal cycling, particularly during the early hydration period. 1. Introduction The good durability of Portland cement compositions in normal service environments has long been recognized. However, cements and concretes made with cement binders can be attacked and, as a result, exhibit a reduced service life. Most of the adverse conditions are recognized from experience and have been the subject of numerous examinations of field concretes as well as laboratory studies. Not surprisingly, research and testing have focused on the areas of underperformance. The concept of a “service life” is not new. The ancient world used stone, brick, tile and, from Roman times onwards, concrete, because of their permanence. Today cement and Portland cement concrete are widely used and comprise the world’s major structural material.
Durability of Concrete – Degradation Phenomena Involving Detrimental Chemical Reactions
May 06, 2023
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