Browsing by Keyword "Metakaolin"
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Item Freeze-thaw resistance of blended cements containing calcined paper sludge(2009-08) Vegas, I.; Urreta, J.; Frías, M.; García, R.; GENERAL; Infraestructuras y Servicios CorporativosThis work deals with the frost resistance of blended cements containing calcined paper sludge (source for metakaolin) as partial Portland cement replacements. Freeze-thaw tests were performed on blended cement mortars containing 0%, 10% and 20% waste paper sludge calcined at 650 °C for 2 h. Cement mortar specimens were exposed to freezing and thawing cycles until the relative dynamic modulus of elasticity fell below 60%. The performance of the cement mortars was assessed from measurements of weight, ultrasonic pulse velocity, compressive strength, mercury intrusion porosimetry and SEM. Failure of the control cement mortar occurred before 40 freeze/thaw cycles, while cement mortar containing 20% calcined paper sludge failed after 100 cycles. After 28 and 62 freezing and thawing cycles, cement blended with 10% and 20% calcined paper sludge exhibited a smaller reduction in compressive strength than the control cement.Item Obtención de una adición puzolánica a partir de la calcinación controlada de lodos de destintado de papel: Estudio de prestaciones en matrices de cemento(2006-07) Vegas, I.; Frías, M.; Urreta, J.; San José, J. T.; GENERAL; Infraestructuras y Servicios CorporativosMineralogically, the paper mill sludge consists essentially of calcite, kaolinite, talc and other philosilicates (illite, chlorite). When such sludge is subjected to controlled thermal treatment, its kaolinite component may be transformed into metakaolin, yielding a product with high pozzolanic reactivity. This study was designed to analyze a number of scientific questions around the production of pozzolanic additions via controlled thermal activation of paper mill sludge and to evaluate the performance of such additions when included in a cement matrix. The findings show that paper mill waste activation is optimal when the sludge is calcined for 2 hours at 700°C in the 700-800°C intervale. A comparative study between the cement made with the new addition and a commercial cement (CEM I-42.5R) used as a reference led to highlight the scientific and technical viability of this waste as a cementing seconding material.