Browsing by Author "Urreta, J."
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Item Aging and durability of ternary cements containing fly ash and activated paper sludge(2014-02-15) Vegas, I.; Gaitero, J. J.; Urreta, J.; García, R.; Frías, M.; GENERAL; Tecnalia Research & Innovation; ECOEFICIENCIA DE PRODUCTOS DE CONSTRUCCIÓN; Infraestructuras y Servicios CorporativosThis research work deals with durability aspects of ternary cements containing 79 wt.% ordinary Portland cement (CEM I), 10.5 wt.% coal fly ash and 10.5 wt.% thermally activated paper sludge. Aging tests were performed to study the resistance of the new ternary cement matrixes to the following aggressive exposure conditions: accelerated freeze/thaw cycles, marine environment and Spanish plateau climate conditions. Ternary cements revealed a high resistance to accelerated freeze/thaw cycles. In addition, after 18 months of exposure, they exhibited enhanced performance under marine conditions and similar resistance to Spanish plateau's climate, compared to ordinary Portland cement.Item Conversion and re-use of paper sludge in a pozzolanic material for the construction(2005) Frías, M.; De Rojas, M. I.Sánchez; Urreta, J.; Vegas, I.; San José, J. T.; García, R.; Vigil, R.; Gaballah, I.; Mishra, B.; Solozabal, R.; Tanaka, M.; Infraestructuras y Servicios Corporativos; GENERALThis paper describes the approach and objectives of the research project as well as the results obtained in the initial phases. The starting waste used for this research is a Spanish paper sludge coming from a paper industry which uses 100% of recycled paper as raw material. The first results show that the calcining temperature and stay in furnace play an important role on the pozzolanic activity of the calcined product and in its reaction kinetics. Calcining temperatures of 700°C and 2 hours of stay were the fixed conditions in order to get the best pozzolanic properties for this calcined sludge.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.Item Reuse of waste paper sludge as supplementary cementing material(Minerals, Metals and Materials Society, 2008) Frías, M.; Rodríguez, O.; De Rojas, M. I.Sánchez; Nebreda, B.; Vegas, I.; Urreta, J.; García, R.; Vigil, R.; GENERAL; Infraestructuras y Servicios CorporativosThis paper shows the possibility of reutilize paper sludge waste as supplementary cementing material for the cement manufacture. This industrial waste consists essentially of a mixture of organic matter (30%) and inorganic compound, such as calcite and clay minerals. The raw paper sludge does not present pozzolanic properties, but once calcined at 650°C during 2 hours, exhibits high pozzolanic activity, similar to silica fume at 28 days, as a consequence of the transformation of kaolinite into metakaolinite. Calcined paper sludge was used as partial Portland cement replacements of 0, 5, 10 and 20%. Enhancement in compressive strength was appreciably obtained for 10 and 20% substitution levels from 7 days on. Furthermore, calcined paper sludge slightly reduces the initial and final setting times of cement paste.