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The object of research is fine-grained concrete with carbon black additive obtained from the recycling of rubber tires. This study aims to determine a method for introducing carbon black into fine-grained concrete that achieves the best strength characteristics. The first method involves the preliminary preparation of a suspension by mixing a superplasticizer, carbon black, and part of the water. The second is the granulation of carbon black together with a superplasticizer in the ratio water: superplasticizer = 9: 1, followed by its introduction into the dry mixture and the addition of water at the last stage of mixing the raw material mixture. The addition of carbon black in powder form to the concrete mixture resulted in a decrease in strength from 35.1 MPa (without carbon black) to 34.9–25.6 MPa (with 4–12% carbon black). The effectiveness of the method of introducing granular carbon black was established, with an increase in strength by 40% in relation to the mixture obtained by the first method. The best strength of 50 MPa was demonstrated by the mix with 4% granular carbon black, which was 6% higher than that of the reference mix. Granulation of carbon black makes it possible to reduce its hydrophobicity and solve the problem of uniform distribution of carbon particles during homogenization of the raw material mixture in the presence of water.

The building materials science at the present stage is aimed at expanding the components of composites. At the same time, these components acquire special value with the simultaneous disposal of various wastes. One of such materials that have not been studied before are molten spherical basalt particles (beads) formed as waste in the production of heat-insulating materials. The aim of the article was to study the effect of balls on the structure formation of cement materials. The vibration spectra of basalt balls, which differ from the spectra of pure silica, were studied, which makes it possible to form silicates with different contents of aluminum and iron. The revealed features of the particle surface morphology, grain composition and the presence of amorphous silicate phases in this material confirm its effective use as an active mineral additive in cement concretes of normal and autoclaved hardening. The activity of this binder component is confirmed by the fact that after 180 min 15 mg/g calcium hydroxide is absorbed. SEM images confirmed compaction of the microstructure of cement composites containing crushed basalt granules. As a result of the use of this new additive, the compressive strength increases, while the maximum effect is achieved when 5–10% of finely ground basalt balls are introduced into the mixture. Amorphous quartz accelerates the pozzolanic reaction, increasing the packing density of hydration products. These basalt granules are able to accumulate water, which then takes part in the hydration reaction in a dosed manner. The increased water-holding capacity of the created binder creates conditions for the consistent growth of hydrated products and for synthesis with minimal internal stresses and volumetric deformations.

Alkali-activated binders based on technogenic fibrous waste (TFW) were developed. An increase in the specific surface area (Ssp) of TFW makes it possible to change the strength parameters. Thus, at Ssp = 160 m2/kg, the strength of the binder was 1 MPa, at Ssp = 220 m2/kg, an increase in activity by almost 3 times is noted (compressive strength 3.2 MPa). With an increase in the specific surface of the particles, the microstructure of the binder samples is characterized by a higher density, with a small number of cavities not filled with hydration products. Analysis of the microstructure revealed the presence of a denser matrix in all cases compared to the compositions obtained with a lower specific surface area of TFW. The pressed sample has a dense matrix with an increased number of contact zones between particles; TFW fibers are clearly visible over the entire surface under study. When the alkaline activator NaOH is introduced into the system, the solubility of the crystalline phases of pyroxenes (albite, anorthite) and quartz increases, which is noted by a decrease in the intensity of diffraction reflections. The main chemical composition in the binder is represented by oxides of SiO2, Na2O, CaO, MgO, Al2O3. The presence of sodium-calcium hydroaluminosilicate compounds in the synthesized system of compounds is confirmed by differential thermal analysis. The endothermic peak at 733 °C is associated with the decomposition of sodium-calcium hydroaluminosilicates. The exoeffect peak at 900 °C is associated with the crystallization of tobermorite-like compounds C–A–S–H and C–S–H into wollastonite. The presence of hydrosilicate tobermorite-like compounds is also confirmed by microstructural analysis, where almost the entire surface of waste particles is covered with fibrous new growths, which, most likely, belong to calcium silicate hydrates of tobermorite type C–A–S–H.

The cellulose-enriched tertiary cell walls present in many plant fibers have specific composition, architecture, machinery of formation, and function. To better understand the mechanisms underlying their mode of action and to reveal the peculiarities of fibers from different plant species, it is necessary to more deeply characterize the major components. Next to overwhelming cellulose, rhamnogalacturonan I (RG-I) is considered to be the key polymer of the tertiary cell wall; however, it has been isolated and biochemically characterized in very few plant species. Here, we add RG-I to the list from the phloem fibers of the Phaseolus vulgaris stem that was isolated and analyzed by nuclear magnetic resonance (NMR), dynamic light scattering, and immunolabeling, both within tissue and as an isolated polymer. Additionally, fibers with tertiary cell walls from nine species of dicotyledonous plants from the orders Malphigiales, Fabales, and Rosales were labeled with RG-I-related antibodies to check the presence of the polymer and compare the in situ presentation of its backbone and side chains. The obtained results confirm that RG-I is an obligatory polymer of the tertiary cell wall. However, there are differences in the structure of this polymer from various plant sources, and these peculiarities may be taxonomically related.

Currently, a very significant environmental problem is the increase in the accumulation of solid domestic and industrial waste, including the polymer composition. There is a need to involve these wastes in processing, including in the production of building materials. On this way, the issue of reducing the energy intensity of grinding technogenic polymeric materials is relevant. For the secondary use of technogenic fibrous waste in construction, it is necessary to use special technological mechanisms that are not currently available. To fill this gap, an apparatus with a multi-link working body was developed, which was the objective of this article. The optimal technical characteristics of the apparatus were determined when modeling the process of complex processing of technogenic fibrous materials with sizes of single pieces of 30–100 mm dimensions of the working chamber L × B × H = (420 × 350 × 400) · 10-3 m, maximum dimensions of the screening openings of the chain cloth l = (20 × 25) · 10-3 m; frequency of rotation of the output shaft of the motor-reducer n = 50–600 rpm; oscillation amplitude of the drive link А = (50–60) · 10-3 m; electric motor power N = 1.1 kW; working length of elements for the intensification of the working process of cutting 50 · 10-3 m; needle 70 · 10-3 m; unit weight m = 55 kg. The technological capabilities of the developed apparatus were established: active movement of material in the working space, high screening capacity, creation of complex spatial shear deformation of the material being processed, the implementation of the self-cleaning effect, a developed working surface, the possibility of removing waste inclusions from the technogenic charge during processing.

The current stage of development of building materials science is characterized by the widespread use of dispersed reinforcement of various compositions and sizes in mortars and concretes. In the paper, priority scientific and technical directions for the rational use of reinforcing fibers, including secondary ones, was established for the effective development of resource and energy-saving technologies and the production of competitive commercial products in the construction industry. A study of the phase formation of concrete using technogenic fibrous materials was carried out. Using scanning electron microscopy for the obtained samples, a positive effect of the introduced additive to the packing density of the new formations of the composite with a simultaneous micro-reinforcing effect was revealed. According to the results of X-ray diffraction analysis, in samples using technogenic fibrous materials, the processes of dissolution of clinker minerals are activated with a simultaneous decrease in Ca(OH)2 reflections, which indicates its binding to hydrate neoformations CSH. Identification of CSH hydrated phases is noted by differential thermal analysis, where the release of bound water from the CSH hydrogel is due to the deepest endo effect at temperatures around 90–110 ºС. The high-temperature exoeffect with a maximum at 899 °C is associated with gel crystallization into low-basic calcium silicate hydrate modifications. Thus, the structure formation of highly effective cement materials was controlled through the use of technogenic fibrous materials such recycled basalt wool. At 28 days aged, compressive strength of the cement composites rises to 26%, and flexural strength up to 62% by applying recycled basalt wool waste.

A promising method of obtaining mineral fiber fillers for dry building mixtures is the processing of waste that comes from the production of technogenic fibrous materials (TFM). The novelty of the work lies in the fact that, for the first time, basalt production wastes were studied not only as reinforcing components, but also as binder ones involved in concrete structure formation. The purpose of the article is to study the physical and mechanical properties of waste technogenic fibrous materials as additives for optimizing the composition of raw concrete mixes. To assess the possibility of using wastes from the complex processing of TFM that were ground for 5 and 10 min as an active mineral additive to concrete, their chemical, mineralogical, and granulometric compositions, as well as the microstructure and physical and mechanical characteristics of the created concretes, were studied. It is established that the grinding of TFM for 10 min leads to the grinding of not only fibers, but also pellets, the fragments of which are noticeable in the total mass of the substance. The presence of quartz in the amorphous phase of TFM makes it possible to synthesize low-basic calcium silicate hydrates in a targeted manner. At 90 days age, at 10–20% of the content of TFM, the strength indicators increase (above 40 MPa), and at 30% of the additive content, they approach the values of the control composition without additives (above 35 MPa). For all ages, the ratio of flexural and compressive strengths is at the level of 0.2, which characterizes a high reinforcing effect. Analysis of the results suggests the possibility of using waste milled for 10 min as an active mineral additive, as well as to give better formability to the mixture and its micro-reinforcement to obtain fiber-reinforced concrete.

In the fibers of many plant species after the formation of secondary cell walls, cellulose-enriched cell wall layers (often named G-layers or tertiary cell walls) are deposited which are important in many physiological situations. Flax (Linum usitatissimum L.) phloem fibers constitutively develop tertiary cell walls during normal plant growth. During the gravitropic response after plant inclination, the deposition of a cellulose-enriched cell wall layer is induced in xylem fibers on one side of the stem, providing a system similar to that of tension wood in angiosperm trees. Atomic force microscopy (AFM), immunochemistry, and transcriptomic analyses demonstrated that the G-layer induced in flax xylem fibers was similar to the constitutively formed tertiary cell wall of bast (phloem) fibers but different from the secondary cell wall. The tertiary cell walls, independent of tissue of origin and inducibility, were twice as stiff as the secondary cell walls. In the gravitropic response, the tertiary cell wall deposition rate in xylem was higher than that of the secondary cell wall. Rhamnogalacturonan I (RG-I) with galactan side chains was a prominent component in cellulose-rich layers of both phloem and xylem flax fibers. Transcriptomic events underlying G-layer deposition in phloem and xylem fibers had much in common. At the induction of tertiary cell wall deposition, several genes for rhamnosyltransferases of the GT106 family were activated in xylem samples. The same genes were expressed in the isolated phloem fibers depositing the tertiary cell wall. The comparison of transcriptomes in fibers with both inducible and constitutive tertiary cell wall deposition and xylem tissues that formed the secondary cell walls is an effective system that revealed important molecular players involved in the formation of cellulose-enriched cell walls.

The goal of any plant breeding program is to improve quality of a target crop. Crop quality is a comprehensive feature largely determined by biological background. To improve the quality parameters of crops grown for the production of fiber, a functional approach was used to search for genes suitable for the effective manipulation of technical fiber quality. A key step was to identify genes with tissue and stage-specific pattern of expression in the developing fibers. In the current study, we investigated the relationship between gene expression evaluated in bast fibers of developing flax plants and the quality parameters of technical fibers measured after plant harvesting. Based on previously published transcriptomic data, two sets of genes that are upregulated in fibers during intrusive growth and tertiary cell wall deposition were selected. The expression level of the selected genes and fiber quality parameters were measured in fiber flax, linseed (oil flax) cultivars, and wild species that differ in type of yield and fiber quality parameters. Based on gene expression data, linear regression models for technical stem length, fiber tensile strength, and fiber flexibility were constructed, resulting in the identification of genes that have high potential for manipulating fiber quality. Chromosomal localization and single nucleotide polymorphism distribution in the selected genes were characterized for the efficacy of their use in conventional breeding and genome editing programs. Transcriptome-based selection is a highly targeted functional approach that could be used during the development of new cultivars of various crops.

Cell wall thickening and development of secondary cell walls was a major step in plant terrestrialization that provided the mechanical support, effective functioning of water-conducting elements and fortification of the surface tissues. Despite its importance, the diversity, emergence and evolution of secondary cell walls in early land plants have been characterized quite poorly. Secondary cell walls can be present in different cell types with fibers being among the major ones. The necessity for mechanical support upon increasing plant height is widely recognized; however, identification of fibers in land plants of early taxa is quite limited. In an effort to partially fill this gap, we studied the fibers and the composition of cell walls in stems of the sporophyte of the living fossil Psilotum nudum. Various types of light microscopy, combined with partial tissue maceration demonstrated that this perennial, rootless, fern-like vascular plant, has abundant fibers located in the middle cortex. Extensive immunodetection of cell wall polymers together with various staining and monosaccharide analysis of cell wall constituents revealed that in P. nudum, the secondary cell wall of its cortical fibers is distinct from that of its tracheids. Primary cell walls of all tissues in P. nudum shoots are based on mannan, which is also common in other extant early land plants. Besides, the primary cell wall contains epitope for LM15 specific for xyloglucan and JIM7 that binds methylesterified homogalacturonans, two polymers common in the primary cell walls of higher plants. Xylan and lignin were detected as the major polymers in the secondary cell walls of P. nudum tracheids. However, the secondary cell wall in its cortical fibers is quite similar to their primary cell walls, i.e., enriched in mannan. The innermost secondary cell wall layer of its fibers but not its tracheids has epitope to bind the LM15, LM6, and LM5 antibodies recognizing, respectively, xyloglucan, arabinan and galactan. Together, our data provide the first description of a mannan-based cell wall in sclerenchyma fibers, and demonstrate in detail that the composition and structure of secondary cell wall in early land plants are not uniform in different tissues.

Our study is the first to consider the changes in the entire set of matrix plant cell wall (PCW) polysaccharides in the course of a plant infectious disease. We compared the molecular weight distribution, monosaccharide content, and the epitope distribution of pectic compounds and cross-linking glycans in non-infected potato plants and plants infected with Pectobacterium atrosepticum at the initial and advanced stages of plant colonization by the pathogen. To predict the gene products involved in the modification of the PCW polysaccharide skeleton during the infection, the expression profiles of potato and P. atrosepticum PCW-related genes were analyzed by RNA-Seq along with phylogenetic analysis. The assemblage of P. atrosepticum biofilm-like structures—the bacterial emboli—and the accumulation of specific fragments of pectic compounds that prime the formation of these structures were demonstrated within potato plants (a natural host of P. atrosepticum). Collenchyma was shown to be the most “vulnerable” tissue to P. atrosepticum among the potato stem tissues. The infection caused by the representative of the Soft Rot Pectobacteriaceae was shown to affect not only pectic compounds but also cross-linking glycans; the content of the latter was increased in the infected plants compared to the non-infected ones.

The plant cell wall is a complex structure consisting of a polysaccharide network. The rearrangements of the cell wall during the various physiological reactions of plants, however, are still not fully characterized. Profound changes in cell wall organization are detected by microscopy in the phloem fibers of flax (Linum usitatissimum) during the restoration of the vertical position of the inclined stems. To characterize the underlying biochemical and structural changes in the major cell wall polysaccharides, we compared the fiber cell walls of non-inclined and gravistimulated plants by focusing mainly on differences in non-cellulosic polysaccharides and the fine cellulose structure. Biochemical analysis revealed a slight increase in the content of pectins in the fiber cell walls of gravistimulated plants as well as an increase in accessibility for labeling non-cellulosic polysaccharides. The presence of galactosylated xyloglucan in the gelatinous cell wall layer of flax fibers was demonstrated, and its labeling was more pronounced in the gravistimulated plants. Using solid state NMR, an increase in the crystallinity of the cellulose in gravistimulated plants, along with a decrease in cellulose mobility, was demonstrated. Thus, gravistimulation may affect the rearrangement of the cell wall, which can enable restoration in a vertical position of the plant stem.

Abstract  The gelatinous type of secondary cell wall is present in tension wood and in phloem fibers of many plants. It is characterized by the absence of xylan and lignin, a high cellulose content and axially orientated microfibrils in the huge S2 layer. In flax phloem fiber, the major non-cellulosic component of such cell walls is tissue-specific galactan, which is tightly bound to cellulose. Ultrastructural analysis of flax fiber revealed that initiation of gelatinous secondary cell wall formation was accompanied by the accumulation of specific Golgi vesicles, which had a characteristic bicolor (dark-light) appearance and were easily distinguishable from vesicles made in different tissues and during the other stages of fiber development. Many of the bicolor vesicles appeared to fuse with each other, forming large vacuoles. The largest observed was 4 μm in diameter. Bicolor vesicles and vacuoles fused with the plasma membrane and spread their content in a characteristic “syringe-like” manner, covering a significant area of periplasm and forming “dark” stripes on the inner wall surface. Both Golgi derivatives and cell wall layers were labeled by LM5 antibody, indicating the presence of tissue- and stage-specific (1→4)-β-galactan. We suggest that this specific type of galactan secretion, which allows coverage of a large area of periplasm, is designed to increase the chance of the galactan meeting the cellulose microfibrils while they are still in the process of construction. The membrane fusion machinery of flax fiber must possess special components, which may be crucial for the formation of the gelatinous type cell wall. [ABSTRACT FROM AUTHOR]