Topic
Ettringite
About: Ettringite is a research topic. Over the lifetime, 2702 publications have been published within this topic receiving 67056 citations. The topic is also known as: woodfordite.
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TL;DR: In this paper, the physicochemical interaction of a high free lime (CaO) content cement kiln dust (CKD) with expansive Na-montmorillonite clay is presented.
81 citations
TL;DR: In this paper, the effect of natural and heated wood on the hydration of cement at early ages was investigated by isothermal calorimetry, thermogravimetry (TGA) and Fourier transform infrared (FTIR) spectroscopy.
Abstract: Heat treatments of wood are widely used for the reduction of wood swelling and dimensional instability of wood-cement composites. The effect of natural and heated wood on the hydration of cement at early ages was investigated by isothermal calorimetry, thermogravimetry (TGA) and Fourier transform infrared (FTIR) spectroscopy. The addition of wood strongly delays and inhibits the hydration of the silicate phases. Consequently, the amount of portlandite is lower in composites than in neat cement. Approximately 30% of the inhibition of portlandite precipitation is due to an increase of calcium carbonate content in cement paste. The absorption of a part of water by wood produces a decrease in gypsum consumption. Nevertheless, the ettringite formation is not significantly affected since a diffusion of sulfate ions from wood occurs.
81 citations
TL;DR: In this article, the deterioration of slag cement blends to those of plain Portland cement was compared and it was shown that this occurs more through loss of surface than macroscopic expansion.
80 citations
TL;DR: In this article, Petrographic scanning electron microscope (SEM) and energy-dispersive analytical X-ray (EDAX) studies were conducted to determine the abundance, spatial location, and morphology of ettringite and the spatial relationship of ETTringite to the occurrence of oxidized pyrite and coarse/fine carbonate aggregate.
80 citations
TL;DR: In this paper, the main hydrates formed during the hydration of the low-alkali cement "ESDRED" consisting of 60% CEM I, 40% microsilica and 4.8% set accelerator are shown to be stable in contact with the clay-based barriers of a repository for radioactive waste.
Abstract: Ettringite and C–S–H are the main hydrates formed during the hydration of the low-alkali cement “ESDRED” consisting of 60% CEM I, 40% microsilica and 4.8% set accelerator. Small quantities of portlandite and hemicarbonate present as intermediate phases destabilise within a few weeks. The use of a set accelerator leads to massive ettringite precipitation, a moderate decalcification of C–S–H and reduction of pH due to presence of dissolved formate. The slow reaction of the silica fume during hydration decalcifies the C–S–H and decreases the alkali concentration to 30 mM and the pH value of the pore solution to 11.5 after 1 year and longer. The further reaction of the silica fume is expected to be slow and to result in a decrease of pH to 11. Further, the destabilisation of ettringite to thaumasite is expected. The long-term stability of C–S–H and the pH of approximately 11 make ESDRED a good candidate for usage in contact with the clay-based barriers of a repository for radioactive waste.
80 citations