The alkali–silica reaction forms bexternal C–S– and/or C–K–S–H gelsQ generally observed, but the originality of this study is to establish the consequences inside the flint aggregate. Observations by microscopy show the following points:
– the alteration faces of grains,
– the amorphization of the flint aggregate,
– the visualization of the attack mode through diffusion of potassium and calcium ions.