Analysis of the Synthetic Fiber Influence on the Cement Stone New Formations Composition in Foam Concrete

The relevance of the search for scientifically grounded tools, with the help of which it is possible to ensure the growth of crack resistance and strength of foam concrete, is noted. The systemic need of the building complex for energy-and resource-saving operationally reliable building materials is emphasized. The positive influence of the surface energy potential of the fibrous fiber of polymer and carbon composition on the possibility of forming an improved structure of the cement stone in the composition of the interpore partitions of foam concrete has been scientifically substantiated. The article provides information on the foam mixtures formulation and the timing of their hardening. The scans of the investigated materials’ X-ray diffraction patterns and the identification table of the detected hydration neoplasms of the cement stone are presented. The scientific substantiation reliability is experimentally confirmed by the results of the analysis performed, from which it follows that all foam concretes contain quartz, portlandite, hydro-aluminates and calcium hydro-silicates. It has been established that the introduction of fiber into the foam mixture formulation creates the prerequisites for the appearance of such varieties of the hydrated silicate phase as nekoite, which has a fibrous structure at the nanoscale, and foshagite, which has an acicular structure of crystals with increased hardness. The listed mineral hydrated new formations of cement stone, due to their individual properties, should contribute to the foam concrete operational properties’ improvement.

Li and B diffusivity in hydrated silicate melts: an experimental study

<p>Magmatic volatiles play a major role in controlling magma dynamics, such as ascent characteristics and eruption style. In order to fully understand their influence in magmatic systems, it is crucial to examine their behaviour within silicate melts. Although numerous studies have been conducted on volatile solubility, exsolution and degassing, some aspects of  magma degassing such as bubble formation, bubble growth and the affect on the distribution of fluid-mobile elements are poorly understood. For instance, magma degassing is likely to affect the abundance and dispersion of fluid-mobile elements, such as Li and B, in the magma. Thus, this study focuses on the diffusivity of Li and B in hydrated silicate melt as a proxy for degassing processes.</p><p>Lithium and boron are particularly suitable as geochemical tracers of degassing processes because they are light elements, present in natural volcanic systems in low concentrations, and have similar characteristics: both elements are fluid-mobile and each has two stable isotopes with different transport behaviours due to their atomic weights, which can lead to isotope fractionation. In order to successfully model their behaviour during magmatic ascent, their diffusivities in silicate melts have to be well constrained.</p><p>Diffusion data in hydrous settings are missing or underrepresented: very little studies have been conducted on boron diffusivity, the literature gives contradictory diffusion coefficients for lithium. In this study, we focus on elemental diffusion and isotopic fractionation of lithium and boron in hydrated silica-rich melts, in order to better understand B diffusivity and solve the discrepancies about Li data.</p><p>Sets of diffusion-couple experiments on synthetic water-bearing rhyolitic glasses have been performed, using an internally heated pressure vessel, at a constant pressure of 300 MPa and temperatures of 700°, 800° and 1000° C, with durations of 0 seconds, 30 minutes, 2 hours and 4 hours. Lithium and boron elemental concentrations have been measured by LA-ICP-MS, resulting in 600 μm long profiles, while isotopic ratios are being evaluated by SIMS analysis.</p><p>The zero-hour experiment indicates that lithium diffuses very rapidly, potentially already at temperatures below 700° C (during the heating process), while boron diffusion is generally slower, hence the necessity of higher temperatures and longer experimental run durations. Overall, our experimental results confirm previous literatue findings that Li diffuses faster in water-bearing melts, and give first constraints on boron diffusivity in hydrated silicate melts, whereas previous studies only considered anhydrous samples. The determination of diffusion coefficients of the two elements gives us a better understanding of the diffusion timescales. This information allows us to interpret additional decompression experiments, simulating a wide range of magma ascent rates, and to correlate the elemental and isotopic behaviour of lithium and boron with decompression-induced bubble formation processes.</p>

Organofunctionalization of Natural Palygorskite with Ethylene Sulfide in the Absence of a Solvent

The search for functional materials has increased daily in order to improve their functionality while maintaining a low cost. Among the materials of considerable interest are clays and within them is a particular clay known as palygorskite, which contains a hydrated silicate of aluminum and magnesium with a fibrous morphology. This work achieved the organofunctionalization of palygorskite with ethylene sulfide in the absence of a solvent. Through the elemental analysis of sulphur, the incorporation of 9.73 ± 0.36 mmol g-1 was identified. A significant decrease in the crystallographic planes (110) and (040) was identified in the XRD. The FTIR showed vibrations of stretching and deformation of the methylene groups in the region below 3000 and in 1421 cm-1, respectively. The deformation related to the C-S group in the region of 700 and 600 cm-1, and the surface area (BET) showed a significant reduction from 113 to 7 m2 g-1. Additionally, the SEM presented a loss of fibrous character.

Occurrence of a skarn-type mineralogy found in Ciénaga Marbles, located in the NW foothills of the Santa Marta Massif (Colombia)

<p>The early Cretaceous Ciénaga Marbles that crop out in the NW foothills of the Santa Marta Massif (Colombian Caribbean region) present an epigenetic mineral assemblage (skarn-type), overprinting the metamorphic mineral assemblage previously developed along the regional metamorphic history that affected this unit. The skarn-type mineralogy allows at least three paragenetic contexts to be distinguished, which are represented by the following neoformed minerals: (a) garnet, forsterite, diopside, titanite, wollastonite and calcite (early anhydrous metamorphic stage), (b) actinolite, tremolite, allanite and clinohumite (metasomatic or hydrated stage), and (c) chlorite, serpentine, sepiolite and quartz (late low temperature retrograde stage, probably due to infiltration of descending meteoric waters). The skarn-type mineralogy is observed as alteration halos developed around porphyritic granodiorites emplaced as sills between anisotropy planes related to metamorphic regional foliation of rock that are considered to be the causative bodies of the skarntype mineralogy. Zircon U-Pb ages obtained from granodioritic bodies yielded an age of 55.5±0.7 Ma (Ypresian, Early Eocene). The formation of the skarn-type mineralogy in the Ciénaga Marbles is temporarily related to the formation and emplacement of hydrated silicate masses that were generated at the beginning of the subduction polarity change (i.e. when the Caribbean oceanic plate began to subduct beneath South American continental plate).</p>

Zeolite synthesis in hydrated silicate ionic liquids

Hydrated alkali silicate ionic liquids (HSIL) were prepared by hydrolysis of tetraethoxysilane (TEOS) in alkali hydroxide–water mixtures, inducing coacervation and phase separation. The resulting optically clear, homogenous silicate ionic liquid offers exceptional potential for monitoring zeolite crystallisation. This enhanced synthesis route provides access to analysis of speciation, mechanistic details of zeolite formation, and brings organic-template-free zeolite synthesis by design within reach.