J. L. Perez-Rodrıguez

arXiv2024

Phase transformation on heating of an aged cement paste

The standard cement paste (C-43-St) was studied previously by static heating, SH, immediately after 1 month hydration at w/c = 0.4 [J. Therm. Anal. Calorim. 69 (2002) 187]. This paste after 5-year ageing (unprotected from contact with air) was subject to thermal analysis in air and in argon (DTA, DTG and TG), to XRD at various temperatures, T, in a high temperature chamber, to mass spectroscopy (MS) and to IR spectroscopy. The aim of this study was to compare the results of SH (fresh paste) and of TG (the aged one), to verify the assumptions made on SH interpretation and to check the change in hydration products with ageing as measured by phase transformation on heating (deltaM versus the final mass).

cond-mat.mtrl-sci↗

arXiv2024

The influence of sonication on the thermal behavior of muscovite and biotite

The differences on the thermal behavior (DTA-TG) of mica samples measured before and after sonication have been studied. Sonication treatment produces important modifications in the thermal behavior of muscovite and biotite samples. For muscovite, it produces a broadening and decrease in temperature of the dehydroxylation and crystallization effects, reaching a steady stage after 40 h treatment time. For biotite, the original single peak profile for the dehydroxylation of the untreated sample is converted into a two peaks profile after sonication, the intensity of the low temperature peak increases with sonication time, while the intensity of the high temperature peak decreases. The modification of the thermal behavior for sonicated samples has been correlated to the particle size distribution effect produced by the sonication treatment. It has been also observed that the cup tip of the sonication equipment contaminates the samples releasing titanium of its composition

cond-mat.mtrl-sci↗