Showing papers by "Jordi Payá published in 2011"
TL;DR: In this article, a sonication process was applied by means of which the deagglomeration of the larger particles of densified silica fume (CSF) was achieved.
Abstract: Currently, the use of silica fume for the production of mortars and high-performance concrete is of great importance to the construction materials sector. Different applications of silica fume have generated extensive studies about its high reactivity as a pozzolanic material, in addition to its effect on the properties of some materials within which it is incorporated. In this study a sonication process was applied by means of which the deagglomeration of the larger particles of densified silica fume (CSF) was achieved. The result is a CSF treated with the ultrasound probe, which is obtained for different tests where the parameters of sonication such as sonication power level and sonication time are varied. This treatment makes it possible to increase the quantity of submicrometric particles in the sample. The effect of sonication process on CSF produces a greater quantity of very fine particles, which improve the pozzolanic reactivity of silica fume and increase the fixation of hydrated lime. This behav...
26 citations
TL;DR: In this article, the reaction between a spent fluid cracking catalyst (FC3R) residue and portlandite was monitored over 56 days using several material characterisation techniques and the results showed that the residue was heterogeneous and composed of reactive and non-reactive fractions and that both fractions contained silicon and aluminium.
Abstract: The reaction between a spent fluid cracking catalyst (FC3R) residue and portlandite was monitored over 56 days using several material characterisation techniques The results showed that the residue was heterogeneous and composed of reactive and non-reactive fractions and that both fractions contained silicon and aluminium After 56 days, the development of C–S–H gel was evident; part of the catalyst residue was pozzolanic The CH combination could be monitored by thermogravimetry or X-ray diffraction, by measuring the signal corresponding to CH However, due to the low crystallinity of cementing products and their complex stoichiometry, the above-mentioned techniques were less able to characterise C–A–S–H However, nuclear magnetic resonance techniques allowed the evolution of the pozzolanic reaction to be evaluated and the hydrate products to be characterised
17 citations
TL;DR: In this paper, the evolution of the microstructure of Portland cement mortar is analyzed, by using electrical impedance measurements Cement mortars are compared without and with two pozzolanic substitutions: spent fluid catalytic cracking catalyst (FCC) and metakaolin (MK) The measurement method is described and the model for analyzing the electrical impedance spectra is developed Three electrical parameters are defined: electrical resistivity, capacitance exponent, and capacitive factor
Abstract: In this paper the evolution of the microstructure of Portland cement mortar is analyzed, by using electrical impedance measurements Cement mortars are compared without and with two pozzolanic substitutions: spent fluid catalytic cracking catalyst (FCC) and metakaolin (MK) The measurement method is described and the model for analyzing the electrical impedance spectra is developed Three electrical parameters are defined: electrical resistivity, capacitance exponent, and capacitive factor The results show a significant increase in resistivity of the mortars with pozzolans after 7 days of curing, especially in mortars with MK This increase is correlated with lime-fixing by the pozzolans The capacitive properties evolve differently at early age, but reach the same values after 148 days The electrical and mineralogical data show that the evolution of the microstructure in the mortar with MK starts before it does in the mortars with FCC and that the final microstructure becomes different
13 citations