| At the present work the replacement of Portland cement in pastes and mortars by spent fluid catalytic cracking catalyst (FCC) is studied. The study has been focused in four physicochemical characterization, hydrated lime/catalyst and cement/catalyst pastes and mortars studies, and environmental impact aspects.; The FCC characterization establishes that it is a silicoaluminate, having a mainly amorphous structure, with a great specific surface, and that is necessary its mechanical activation (grinding) to obtain a pozzolanic behaviour material.; The reactivity was studied by: thermogravimetry, X ray diffractometry, aqueous media electrical conductivity measurements, Fourier transform infrared spectroscopy, scanning electron microscopy, mechanical strength development evaluation and cementing effectiveness k-factor evaluation.; The very high pozzolanic activity of the material has been demonstrated, besides that this reactivity has been superior to others similar products such as the metakaolin.; The products formed in the hydration, pozzolanic and hydration catalysis of cement reactions have been studied, comparing the reactivity characteristics with others better known pozzolans.; The nature of the reaction products between FCC and hydrated lime is similar to the ones formed by the metakaolin, being fundamentally calcium silicate hydrates and hydrated gehlenite, and their formation allow to obtain microstructures with higher mechanical strength.; The possibility of preparation materials containing cement/FCC with improved mechanical strength and drying shrinkage has been demonstrated, compared to homologous materials without ground FCC.; The optimal FCC dosage for the lime fixation maximization has been determined, showing a pozzolanic behaviour similar to metakaolin, nevertheless very superior to others studied pozzolans, behaviour that is improved with the aid of certain chemical activators, and with the increasing of the curing temperature.; Measurements of electrical conductivity in aqueous media have confirmed the great FCC pozzolanic activity, being compared with matakaolin and silica fume.; Mechanical strength studies on pastes and mortars have confirmed the high pozaolanic activity of the catalyst, obtaining k-factor values bigger than the unity.; In spite that the FCC contains minority elements with potential harmful environmental impact, it has been demonstrated that those elements are fixed by the conglomerate matrix, bringing an adequate construction material also from the environmental point of view.*; *Originally published in DAI Vol. 63, No. 1. Republished here with corrected author name. |
