Enthalpy of formation of ye’elimite and ternesite

Calcium sulfoaluminate clinkers containing ye’elimite (Ca4Al6O12(SO4)) and ternesite (Ca5(SiO4)2SO4) are being widely investigated as components of calcium sulfoaluminate cement clinkers. These may become low energy replacements for Portland cement. Conditional thermodynamic data for ye’elimite and ternesite (enthalpy of formation) have been determined experimentally using a combination of techniques: isothermal conduction calorimetry, X-ray powder diffraction and thermogravimetric analysis. The enthalpies of formation of ye’elimite and ternesite at 25 °C were determined to be − 8523 and − 5993 kJ mol−1, respectively

Where less may be more: how the rare biosphere pulls ecosystems strings

Rare species are increasingly recognized as crucial, yet vulnerable components of Earth’s ecosystems. This is also true for microbial communities, which are typically composed of a high number of relatively rare species. Recent studies have demonstrated that rare species can have an over-proportional role in biogeochemical cycles and may be a hidden driver of microbiome function. In this review, we provide an ecological overview of the rare microbial biosphere, including causes of rarity and the impacts of rare species on ecosystem functioning. We discuss how rare species can have a preponderant role for local biodiversity and species turnover with rarity potentially bound to phylogenetically conserved features. Rare microbes may therefore be overlooked keystone species regulating the functioning of host-associated, terrestrial and aquatic environments. We conclude this review with recommendations to guide scientists interested in investigating this rapidly emerging research area

A simple method for determining the total amount of physically and chemically bound water of different cements

ISSN:1388-6150ISSN:1588-292

Influence of calcium nitrate and sodium nitrate on strength development and properties in quicklime(CaO)-activated Class F fly ash system

The single use of CaO has been regarded as relatively unsuccessful in fly ash activation when no other additives are used together, as it produces a considerably lower strength compared to other types of activators (e.g., alkaline activators). This study investigated two potential additives of nitrate compounds (i.e., Ca(NO3)2 and NaNO3) to improve the strength of a CaO-activated fly ash system. The results showed that the use of Ca(NO3)2 was greatly beneficial in the strength improvement of the binder system primarily due to the significant increase in (1) the dissolution degree of fly ash, (2) C???S???H formation, and (3) pore size refinement from early days; however, NaNO3 was much less advantageous in strength improvement, although it also aided in dissolving fly ash