Understanding the relationship between composition and rheology in alkali-activated binders

In this work, an alkali-activated binding system based on electrometallurgical slag, as well as citrogypsum, a waste of the industrial production of citric acid, was studied. Some rheological characteristics of experimental binders were considered: the nature of the mixture flow under the action of torsional loads and their initial and final setting time

Binders from gypsum-containing waste and products based on them

Gypsum binders are among the most environmentally friendly from the point of view of their production. The raw material base for their production is represented not only by natural raw materials, but also by a wide variety of technogenic materials, phosphogypsum is the most multi-ton and studied of them. At the same time, citrogypsum is also a promising raw material for the production of gypsum binders and, in comparison with phosphogypsum, does not contain toxic impurities that require the development of additional measures for their remova

Fossil Microorganisms and Formation of Early Precambrian Weathering Profiles

Weathering crusts are the only reliable evidences of the existence of continental conditions. Often they are the only source of information about exogenous processes and subsequently about conditions under which the development of the biosphere occurred. A complex of diverse fossil microorganisms was discovered as a result of Scanning Electron Microscope investigations. The chemical composition of the discovered fossils is identical to that of the host rocks and is represented by Si, Al, Fe, Ca and Mg. Probably, the microorganisms fixed in rocks played the role of catalyst. The decomposition of minerals comprising the rocks and their transformation into clayey (argillaceous) minerals, most likely occurred under the influence of microorganisms. And may be unique weathering crusts of Early Precambrian were formed due to interaction between specific composition of microorganism assemblage and conditions of hypergene transformations. So it is possible to speak about colonization of land by microbes already at that time and about existence of single raw from weathering crusts (Primitive soils) to real soils

Heat treatment of basalt fiber reinforced expanded clay concrete with increased strength for cast-in-situ construction

Expanded clay concrete (ECC) is a promising structural material for buildings due to its light weight and heat-and sound-insulating properties. Adding basalt fibers (BFs) in ECC reduces its brittleness and enhances its mechanical properties. The heat treatment (HT) of BF-reinforced ECC can significantly accelerate the strength growth during cast-in-situ construction, which allows the reduction of the turnover of the formwork and the construction period, as well as leading to lower construction costs. This paper presents an HT technology for load-bearing structures, containing a BF-reinforced ECC mix and using infrared rays for cast-in-situ construction. The issue of the strength growth of BF-reinforced ECC during HT has been studied. Microsilica and fly ash were added to the ECC mix to obtain a compressive strength of more than 20 MPa. Four different mixes of ECC with chopped BFs in the ratios of 1:0, 1:0.0045, 1:0.009 and 1:0.012 by weight of cement were studied. Test specimens were heated by infrared rays for 7, 9, 11, 13, 16 and 24 h. Then, the heat-treated specimens were tested for compressive strength after 0.5, 4, 12 and 24 h cooling periods. The analysis and evaluation of the experimental data were carried out based on probability theory and mathematical statistics. Mathematical models are proposed for forecasting the strength growth of BF-reinforced ECC during cast-in-situ construction. © 2020 by the authors. Licensee MDPI, Basel, Switzerland