Factores de prevención de la reacción álcali-sílice en los áridos del hormigón

Resumen

Alkali-silica reaction occurs between certain aggregate types and the alkali's in the pore solutions of the cement paste in concrete to form a silica gel. In the presence of free moisture, the gel will expand and manifest in cracking and differential movements in structures as well as other deleterious effects such as reduction in freeze-thaw durability and compressive and tensile strength. The microstructural features of various Spanish alkali-reactive rock types used as concrete aggregate, and other Spanish rock types with possible potential reactivity, have been studied and quantified with petrographic techniques and methods of digital analysis of microscopic and macroscopic image. This results have been related to alkali reactivity as measured by an accelerated mortar bar test. The study demonstrated that the grain size reduction of quartz promoted by metamorphic processes enhances alkali reactivity by increasing the surface area of quartz grain boundaries available for reaction.