CENTRO DE INVESTIGACIONES EN FISICA E INGENIERIA DEL CENTRO DE LA PROVINCIA DE BUENOS AIRES
Unidad Ejecutora - UE
Thermal analysis to assess pozzolanic activity of calcined kaolinitic clays
ALEJANDRA TIRONI; MÓNICA ADRIANA TREZZA; ALBERTO NESTOR SCIAN; EDGARDO FABIÁN IRASSAR
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
Lugar: Berlin; Año: 2014 vol. 117 p. 547 - 547
The use of calcined clays as partial replacement of cement is encouraged since it promotes the reduction of the green-house gas emission and the energy requeriment of cement based material, maintaining or enhacing the mechanical propierties and the durable performance of these materials. In this paper, the use of thermal methods - DTA/TG and calorimetry ? to select and to evalute two kaolinitic clays for their use as pozzolanic materials was explored. The content and cristallinity of kaolinite in clays can be determined by DTA/TG analysis and this technique is also suitable to select the calcination temperature for complete kaolinite dehydroxylation. Calorimetric analysis on blended cements (30% by weigth of replacement) can differentiate the reactivity of calcined kaolinitic clays. Results show that more reactive calcined kaolinitic clay develops the second and third peaks earlier than those of PC with great intensity and high accelaration. The reactivity of calcined clays is associated to raw materials containing kaolinite with high structural disorder that determines calcined clays with large specific surface area, high grindability and small mean particles size (d50) for the same grinding objective. Finally, the DTA/TG analysis can determine the type and the amount of hydrated phases obtained at different ages to evaluate the pozzolanic reaction of calcined clay in accordance with the standardized pozzolanic activity index.