Over the past decade, sodium monofluorophosphate (Na-MFP) gained attention as inorganic self-healing agent on Blast Furnace Slag Cement (BFSC) products. Recent experimental studies revealed the recovering effect of Na-MFP on the microstructure of carbonated BFSC pastes with respect to their frost-salt scaling durability. This study investigates the interactions between pore solution and hydration products of OPC and BFSC pastes that were carbonated and/or vacuum-impregnated with aqueous Na-MFP. Pore solutions of pastes were characterized through systematic E_H-pH- and main element analyses by inductively coupled optical emission spectrometry (ICP-OES). Solid hydration products were analyzed by X-ray powder diffraction (XRD). Results indicate that the impregnation of hardened carbonated cement pastes with aqueous Na-MFP results in a recovery of the initial pH of 98.85% and 79.81%, respectively. Analytical results give insight into hydration and carbonation under the influence of Na-MFP. Results are compared with literature and expose that the hypothesis of crystalline apatite formation in BFSC products must be revised.

The largest differentiation event in Earth and other terrestrial planets was the high-pressure, high-temperature process of metal core segregation from a silicate mantle. The abundant element silicon (Si) can be partially sequestered into the metallic core during metal-silicate differentiation, depending on pressure, temperature and planetary oxidation state. Knowledge of the Si content of a planet's core can constrain the conditions of core formation, but in the absence of direct samples from planetary cores, quantifying core Si content is challenging. One relatively new tool to study core formation in terrestrial planets is based on combining measurements of the Si stable isotopic composition of planetary crust and mantle samples with measurements of the Si stable isotope fractionation between metal and silicate at high-temperature and high-pressure conditions. In this study we present the results of a small set of high-pressure, high-temperature (HPT) experiments and combine these with a review of literature data to investigate how the Si isotope fractionation behaviour between metal and silicate varies as a function specifically of experimental run time and temperature. We show that although there is no debate about the sign of fractionation, absolute values for Si isotope fractionation between metal and silicate are difficult to constrain because the experimental database remains incomplete, and because Si isotopic measurements of metals in particular suffer from the absence of a true inter-laboratory comparison. We conclude that in order to derive accurate quantitative estimates of the Si content of the core of the Earth or other planets a wide range of additional experiments will be required.