Browsing by Author "Vigil De La Villa, R."
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Item The combined effect of activated paper sludge and fly ash on the ternary cement properties(European Conference on Composite Materials, ECCM, 2012) Frías, M.; Vegas, I.; Goñi, S.; García, R.; Vigil De La Villa, R.; GENERALThis paper presents the main scientific and technical aspects of a pozzolans blend (activated paper sludge (APS) and fly ash (FA)) and its influence on the ternary cement behaviour. Due to the high pozzolanic activity of binary addition, the blended cements (6 and 21%) shows a different behaviour with respect to the control one. The normal consistency water content (up to 10%) and the initial setting decrease in comparison with the control paste. Finally, the compressive strength slightly decreased in the blended cements elaborated with 21% of the pozzolan blend, although the decrease in their strength is lower than the total percentage of cement that is replaced. At 90 days, a recovery of mechanical resistance is observed in the ternary cements as a consequence of the activity developed by the fly ash.Item Effect of ternary cements containing thermally activated paper sludge and fly ash on the texture of C-S-H gel(2012-05) Goñi, S.; Frias, M.; Vegas, I.; García, R.; Vigil De La Villa, R.; GENERALThe texture of the C-S-H gels formed in ternary cement blends containing thermally activated paper sludge (APS), fly ash (FA) from coal combustion and Ordinary Portland Cement (OPC) was studied by means of the specific surface area (SSA) and pore-size distribution (PSD), which were measured by the sorption isotherms of nitrogen gas and the BET method. Two differentiated zones in the PSD of the C-S-H gel at ∼10-20 nm and ∼5 nm were observed. The proportion of such zones depends on the age of hydration and amount of OPC replacement. The incorporation of the additions (APS and FA) clearly revealed an increase in both porosity and SSA. This effect decreased with the progress of hydration together with a refinement of the nano-porous structure of C-S-H. High correlations were found among these nanostructure characteristics of the C-S-H gel and mechanical strengths.Item Use of coal mining waste as pozzolanic material in new blended cement matrixes(European Conference on Composite Materials, ECCM, 2014) Vigil De La Villa, R.; García, R.; Ramírez, M.; Rubio, V.; Frías, M.; Rodríguez, O.; Lahoz, E.; Martínez-Ramirez, S.; Fernández-Carrasco, L.; Vegas, I.; GENERALResearch and eco-innovation geared to obtain alternative sources of raw materials from waste constitute pathways for enhancing the competitiveness of resource-intensive industries. Cement and concrete manufacture calls for new sources of new, highly pozzolanic products to improve the mechanical properties and durability of the resulting matrices, while at the same time reducing production costs and environmental impact. Spanish coal mining wastes generated in the extraction and washing steps from a mine in the Castilla-León region were investigated. Mineralogically, these wastes are composed by kaolinite (20-30%), illite (45-70%) and quartz (5-15). This composition is very interesting in order to activate, by controlled thermal activation, the present kaolinite that generates metakaolin, a highly pozzolanic product. Morphological, textural and microstructural changes affect the activity and reactivity of activated wastes. These first studies open up a new research line, practically unknown to the international research community, and stand out the important economic and environmental benefits associated with the recycling of these wastes as supplementary cementing materials for future commercial blended cements.