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Research Highlights: When investigating the sorption of water on lignocellulosic materials, the sorption or mixing enthalpy is an interesting parameter that, together with the sorption isotherms commonly measured, can be used to characterize and understand the sorption process. We have compared different methods to assess these enthalpies. Additionally, we propose a sorption nomenclature. Background and Objectives: Sorption enthalpies are non-trivial to measure. We have, for the first time, measured sorption enthalpies on the same materials with four different methods, to be able to compare the method’s strengths and weaknesses. Materials and Methods: The following four methods were used on beech and Scots pine wood: isosteric heat, solution calorimetry, sorption calorimetry, and RH perfusion calorimetry. Results: The results for beech and pine were similar, and were in general agreement with the literature. We do not recommend one of the methods over the others, as they are quite different, and they can therefore be used to elucidate different aspects of the interactions between water and, for example, novel biobased materials (modified woods, cellulose derivatives, and regenerated cellulose).

The reactivities of the binary and ternary mixtures of reactive magnesia (MgO:M), hydratable alumina (Al 2 O 3 :A) and microsilica (SiO 2 :S) micropowders were investigated by calorimetric method and other analytical techniques (X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), differential thermal/thermogravimetric (DTA-TG) analysis and scanning electron microscope (SEM) observations). Effect of water/solid mass ratio and temperature on the hydration behavior of the M-A, M-A-S, M-S, A-M-S and A-S hydratable binders were established. The methodological considerations on both in situ and ex situ mixing techniques have also been taken. The initial mixing peak was due to wetting of the binder particles and initial dissolution reactions. A second, extensive heat peak was associated with the formation of crystalline and noncrystalline hydration products, i.e., brucite Mg(OH) 2 , magnesium aluminate hydrate (MAH; H:H 2 O)-like phase, magnesium silicate hydrate (MSH)-like phase and magnesium aluminum silicate hydrate gels (MASH). Negligible heat was evolved during the hydration reaction of A-S mixture, and the second reaction peak was not observed. Nevertheless, the presence of Al 2 O 3 and SiO 2 in other combinations contributes to the consumption of Mg(OH) 2 which was formed during the initial stages of hydration and leads to the formation of cementitious products, like M-A-H, M-S-H and M-A-S-H.