Abstract
Siliceous aggregates are characterized for presenting certain chemical reactivity opposite to the calcium hydroxide liberated in the hydration of the Portland cement. The consequence of this reaction between the aggregate and the components of the intermediate concrete phase is the formation of gels very eager for water that can generate important disruptive pressures in the deeper structure of concrete. We have assessed the potential reactivity of several siliceous aggregates (granites, gneiss, hornfels, granites, quartzite and serpentine) by means of the accelerated method in concrete bars (normalized method) and the superficial reactivity method, observing by scanning electron microscopy (SEM) the formation of silica calcium alkaline gels. On the other hand, we explore the way of minimizing this disruptive reaction employing ground clay bricks and cement type CEM IV UNE-EN 197-1.
Highlights
Siliceous aggregates are characterized for presenting certain chemical reactivity opposite to the calcium hydroxide liberated in the hydration of the Portland cement
En este trabajo se han empleado dos métodos para evaluar la reactividad potencial de áridos, el
El uso de materiales que presenten actividad puzolánica ha resultado ser una excelente vía para atenuar hasta niveles de elevada seguridad la expansión provocada por la reacción árido-álcali
Summary
Siliceous aggregates are characterized for presenting certain chemical reactivity opposite to the calcium hydroxide liberated in the hydration of the Portland cement. S/UNE-EN 146508:99 EX, empleando como arena los áridos estudiados y relacionando su reactividad con la expansión producida en dichas probetas tras ser atacadas con una disolución 1N de NaOH a 80 °C. El resultado es que las dos corneanas, el gneis y la cuarcita resultan áridos reactivos
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