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Papers by MONICA ALEJANDRA VILLAQUIRAN CAICEDO
Two commercial metakaolins were tested during partial geopolymerization with potassium silicate i... more Two commercial metakaolins were tested during partial geopolymerization with potassium silicate in order to emphasize the different surface reactivities. Both manual and short-term mechanical stirring were used for slurry preparation, while radiation, infrared, and microwave heating were used for curing. The metakaolins had similar compositions and specific surface areas, but different morphologies and dehydroxylation degrees due to different calcination kiln technologies. The degree of geopolymerization was checked by SEM and N 2 adsorption (BET), FTIR and 27 Al MAS NMR spectroscopy. While the dehydroxylation degrees were different, the metakaolins had similar reactivity. The metakaolin powder with rounded agglomerates and lower water demand was more sensitive to the various geopolymerization conditions than the fine dispersed lamellar one, thus giving rise to very different micro-and macrostructures of the partially geopolymerized samples. IR heating seemed to increase the geopolymerization degree slightly, while MW heating induced the fast evaporation of the water, forming porous samples.
Issue 194 by MONICA ALEJANDRA VILLAQUIRAN CAICEDO
Ternary mixtures of geopolymers obtained from the alkaline activation of metakaolin (MK), boiler ... more Ternary mixtures of geopolymers obtained from the alkaline activation of metakaolin (MK), boiler slag (BS), and rice husk ash (RHA)
using a solution of potassium hydroxide were mechanically, thermally, and microstructurally characterized. The geopolymer properties
and final microstructures indicate that the addition of BS, despite containing large amounts of unburned material (16.36%), allows for
greater densification and greater homogeneity of the geopolymeric gel, which results in greater stability in strength at long curing ages.
Substitution of 30% of MK by BS results in an increase in compressive strength of up to 21% and 122% after 28 and 180 days of curing,
respectively. These results demonstrate the possibility of the construction sector using geopolymers based on MK and adding BS and RHA
to obtain cementitious materials with a lower environmental impact.
Two commercial metakaolins were tested during partial geopolymerization with potassium silicate i... more Two commercial metakaolins were tested during partial geopolymerization with potassium silicate in order to emphasize the different surface reactivities. Both manual and short-term mechanical stirring were used for slurry preparation, while radiation, infrared, and microwave heating were used for curing. The metakaolins had similar compositions and specific surface areas, but different morphologies and dehydroxylation degrees due to different calcination kiln technologies. The degree of geopolymerization was checked by SEM and N 2 adsorption (BET), FTIR and 27 Al MAS NMR spectroscopy. While the dehydroxylation degrees were different, the metakaolins had similar reactivity. The metakaolin powder with rounded agglomerates and lower water demand was more sensitive to the various geopolymerization conditions than the fine dispersed lamellar one, thus giving rise to very different micro-and macrostructures of the partially geopolymerized samples. IR heating seemed to increase the geopolymerization degree slightly, while MW heating induced the fast evaporation of the water, forming porous samples.
Ternary mixtures of geopolymers obtained from the alkaline activation of metakaolin (MK), boiler ... more Ternary mixtures of geopolymers obtained from the alkaline activation of metakaolin (MK), boiler slag (BS), and rice husk ash (RHA)
using a solution of potassium hydroxide were mechanically, thermally, and microstructurally characterized. The geopolymer properties
and final microstructures indicate that the addition of BS, despite containing large amounts of unburned material (16.36%), allows for
greater densification and greater homogeneity of the geopolymeric gel, which results in greater stability in strength at long curing ages.
Substitution of 30% of MK by BS results in an increase in compressive strength of up to 21% and 122% after 28 and 180 days of curing,
respectively. These results demonstrate the possibility of the construction sector using geopolymers based on MK and adding BS and RHA
to obtain cementitious materials with a lower environmental impact.