Physico-Chemical Disintegration of Concrete

The purpose of this paper is to list and discuss briefly some of the causes of chemical and physico-chemical disintegration of concrete and to point out some methods that can be used to study these causes. In this paper a distinction is made between physico-chemical (or chemico-physical) and mechanical causes of failure. Processes involving changes in chemical composition (chemical reactions proper), changes in phase of a component (freezing of water and crystallizing of salts in voids), capillary forces, and temperature stresses are considered to be physico-chemical; processes involving stress from the surrounding en­ vironment (traffic loads, uneven swelling of supporting medium, etc.) are considered to be mechanical. As concrete making and study have been evolving from an art to a science, more and more attention has been placed on so-called funda­ mental study of chemical and physical processes in concrete. However, so many variables are involved, and so few organizations are (or con­ sider themselves to be) vitally involved financially, that research on con­ crete has lagged. On the other hand, in the highly organized cement industry fundamental work on the nature and properties of cement has been in progress for many years. At the present time there is a tremendous upsurge of interest in the chemistry and physics of concrete, as evidenced by a voluminous literature. Engineers are realizing that chemical and physical processes of disintegration are responsible for a large portion of concrete failures.