3. Pathology and management of diseased structures

3.1 Description of disorders and screening

The initial presumption of the existence of alkali-reaction in a structure is generally based on the presence of visual symptoms detected during a visit or inspection. Among the best-known manifestations (figure ), we often cite mesh-like cracking, more or less dense depending on the degree of reaction evolution, or oriented when compressive forces oppose internal swelling (in the case of prestressed structures or columns, for example). But a swelling reaction can also give rise to many other forms of apparent damage to a structure, such as movements, deformations, differential swellings, small craters (pop-outs) and so on. In extreme and fortunately rare cases, such as insufficiently reinforced structures, concrete swelling...