MODELING THE ALKALI-AGGREGATE REACTION WI TH DESCRIPTIONS OF THE LOCAL DESTRUCTIVE PHENOMENA INVOLVED

A theoretical model of the alkali-aggregate reaction is described that involves a probabilistic approach. The first part of the model deals with the chemical processes including global and local alkali gradient s, ions substitution and conditions for equilibrium. The second part d escribes the mechanical effects that are induced by expansion due to t he chemical reaction. The probabilistic aspects concern the porosity a nd the reactive aggregates size. The third part provides an applicatio n of the proposed model. The main goals are the calculation of the min imum concentrations of reactive components and the effects of pressure as a result of the confinement of the concrete. Numerical calculation s are compared with experimental results to determine the global kinet ics, the consequences of the chemical reactions, the residual concentr ations of both reactive silica and alkalis, the pressures developed, t he expansion, the mechanical damage, and the crack lengths.