Electron paramagnetic resonance in organic binder aging in dispersely reinforced substructures

Purpose: To study the intensity of binder aging in organo-mineral mixtures using electron paramagnetic resonance. The aging intensity of the organic binder is provided by its concentration in paramagnetic centers, since asphaltenes are almost one hundred percent of paramagnet concentration and indicate to the aging intensity of the petroleum dispersion system.Approach: Dispersed reinforcement of substructures with chemical fibers made of spent sorbents containing a controlled amount of absorbed oil products allows to partially solve the problem of crack formation and fracture of road pavements designed in accordance with the regulatory documents.Research implications: The service life of substructure made of dispersely reinforced organo-mineral mixtures reduces owing to organic binder aging, which begins at the stage of preparation of organo-mineral mixtures and continues during the substructure operation. Organic binder ageing results in the formation of solvation layers on the surface of mineral materials that become more viscous and brittle.Findings: The substructure dispersed reinforcement with chemical fibers made of spent sorbents containing a controlled amount of absorbed oil products decreases the concentration of paramagnetic centers. This indicates to a decrease in the asphaltene concentration, thereby reducing the aging intensity of the oil dispersion system.

The Effect of Mineral-Based Mixtures Containing Coal Fly Ash and Sewage Sludge on Chlorophyll Fluorescence and Selected Morphological Parameters of Deciduous and Coniferous Trees

Coal fly ash (CFA), which is generated in huge quantities in coal-fired power plants, is a problem worldwide. Mixtures with ash and sewage sludge alter morphological and biochemical characteristics of plants. In this experiment, the response of pine, spruce, beech and alder growing for four years to mineral mixtures based on coal fly ash and high salinity sewage sludge (SS) was studied. The four-year experiment determined the chlorophyll a fluorescence of the tested plants, their height and yield, the salinity level of the tested mixtures and their phytotoxicity. Mixtures of coal ash with sewage sludge proved to be more beneficial to plants than their separate application. After four years, among the studied species, the highest increase in height and biomass was recorded for European alder and Scots pine. These species were also characterized by high photosynthetic indices. Mixtures containing 29% SS created optimal conditions for the development of the studied tree species. Grey alder and ponderosa pine can be recommended for reclamation of degraded areas where CFA and SS mixtures are used.

Binder courses using cold recycled mixtures – a novel concept in cold recycling

Cold recycling with cement and bituminous emulsion is one of the most environmentally friendly techniques to maximize the reuse of reclaimed asphalt (RA) collected during demolition of roads. Cold recycled mixtures are commonly used for base courses in construction or rehabilitation of flexible and semi-rigid pavements. Current experiences demonstrated that cold recycling with appropriate requirements and technical recommendations allows long-lasting pavements to be designed. Those outcomes stimulated researchers and engineers in the new challenge of using the cold recycled mixtures in binder layers that are generally more often included in maintenance planning. This paper summarizes current San Marino and Polish experiences with cold recycled mixtures designed for binder layers. The first part of the paper presents the design phase of the cold recycled mixtures in both countries. It describes and compares the composition of the mixtures, grading curves of the mineral mixtures, binding agents and requirements. The second part of the paper shows laboratory test results of mechanical properties of cold recycled mixtures for binder courses including test results in full-scale application.

Technology of 3D Printing of Light Ceramics for Construction Products

A 3D-printer for working with plastic mineral mixtures is developed, its kinematic scheme and principle of operation are described. The results of experiments on printing simple forms of plastic clay, using a piston-type extruder, are presented. In relation to an additive technology, a list of technological properties of mineral masses is defined The optimal amount of chemical additives has been established, which provides an increase in the uniformity of the raw material mass for printing products from light ceramics.

SEM-based mineralogical mapping at the submicrometer-scale of modern Sardinian stromatolites

<p>Stromatolites, i.e. macroscopically laminated carbonate rocks formed by diverse microbial communities, are particularly emblematic geobiological materials since they are the oldest evidence of life-mineral interactions, dated up to 3.5 Gyrs ago.  They are found throughout the history of the Earth and have received strong attention because they provide precious information about microbial paleobiodiversity and paleoenvironments. However, while this information is interpreted based on our knowledge about modern analogs, the latter remains very incomplete. Here, we studied recently discovered modern stromatolites from Mari Ermi<sup>1</sup>, a coastal pond in Western Sardinia, that seasonally experience severe evaporation and broad salinity variations. For this purpose, we explored the mineralogical composition of these unique sedimentary archives and its spatial variations in order to gain better insight into how mineral phases record the conditions and processes of their formation. We investigated the heterogeneous distribution of minerals using quantitative X-ray chemical maps provided by energy dispersive x-ray spectrometry analyses coupled with scanning electron microscopy (SEM-EDXS). Hyperspectral maps were analyzed using an innovative data treatment method <sup>2</sup> allowing phase recognition within the complex mineral mixtures and solid solutions encountered. This method provided quantitative data on spatial distribution, modal content and associated calculated unit formulas for each identified mineral and phase with a hundred nanometer resolution. Based on these results, we will discuss the origin of the laminations in the stromatolites.</p><p>Reference:</p><p>1. Saint Martin, J.-P. & Saint Martin, S. Geo-Eco-Marina <strong>21</strong>, 35–53 (2015a).</p><p>2. Prêt, D. et al. American Mineralogist <strong>95</strong>, 1379–1388 (2010).</p>