Functionality of mortar and concrete mixes is regulated by surfactants, which act as plasticizers. The molecular structure of these admixtures can be changed during hydration of alkali-activated cements (AAC). The objective was to determine the chemical nature of plasticizers effective for property modification of mortars and concretes based on AACs with changing content of granulated blast furnace slag from 0 to 100 %. The admixtures without ester links become more effective than polyesters when content of alkaline component increase. The admixtures effective in high alkaline medium were used in dry mixes for anchoring (consistency of mortar 150 mm by Vicat cone; 1 d tensile strength in bending / compressive strength of mortar 6.6 /30.6 MPa) and in ready-mixed concretes (consistency class changed from S1 to S3, S4 with consistency safety during 60 min; 3 d compressive strength of modified concrete was not less than the reference one without admixtures).
Several approaches can be used to determine the effect of an alkaline environment on glass materials (basalt fibers). One of the most common approaches for the determination of the alkali resistance of a substance is to measure the relative mass loss after the interaction of the object of research with the alkaline environment. According to the practice guidelines, the approach involves determining the alkali resistance of a glass by measuring the mass loss per unit area of the glass under test after boiling it in an alkaline solution. But the disadvantage of this approach is it can’t be applied to basalt or another multicomponent fiberglass as it doesn’t introduce different speeds of fiber dissolution.
In the article the effect of fillers of various chemical nature on the corrosion resistance of polyester powder coatings in terms of flaking widths and corrosion expansion widths in accordance with DSTU ISO 4628-8: 2012 was reviewed. According to the results of studies, the effectiveness of the use of fillers to increase the corrosion resistance of the powder coating varies depending on the average particle size and crystalline form of the filler was found. As a rule, in order to receive a powder coating based decorative coating you should apply only one layer of paint, while liquid coatings require applying several layers; this increases the time of coating production. The powder coating can be easily utilized and recycled, thus the economic feasibility of production increases.
In the article effectiveness of the use of fillers to improve the physical and mechanical properties of the coating varied depending on the average size of the filler particles and crystalline shape was studied. According to the indicators of impact strength to back impact and bending strength of the coating, the most effective is the use of microsilica with an average size of 2.9 μm. As the average filler size increases, the gloss and impact strength of the coating reduce. To increase the bending strength of the coating, it is advisable to use fillers in the form of wollastonite, which is characterized by a fibrous crystal shape, which improves the physical and mechanical properties of the coating and prevents cracking, acting as a reinforcing agent. In addition, the analysis of the obtained study results shows that the use of the studied Ukrainian-made fillers in the powder paint composition promotes obtaining a covering with adjustable physical and mechanical characteristics.
Exhausted etching solutions are the waste of industrial enterprises and contain toxic pollutants that have a detrimental effect on the environment. Currently, the processing of these solutions to obtain marketable products is important. The paper presents the results of research on the application of the ferritization method for processing of exhausted etching solutions of steel surfaces. Energy-saving activation of the process by alternating magnetic fields was used, which has undeniable advantages compared to traditional thermal activation. The influence of the initial concentration of iron ions in the reaction mixture of ferritization process and the methods of its activation on the treatment quality of exhausted etching solutions was studied. It was established that the best degree of extraction of heavy metal ions from exhausted etching solutions by ferritization is achieved when the reaction mixture is activated by alternating magnetic fields at an initial concentration of iron ions of 6.6 g/dm3 . At the same time, the residual concentration of iron ions in purified solutions does not exceed 0.03 mg/dm3 , that corresponds to degree of purification of solutions of 99.999%. Those solutions can be reused in situ. The qualitative and quantitative composition of ferritization sediments was studied. Phases of ferroxygite δ-FeOОН, magnetite Fe3O4 and maghemite ɣ-Fe2O3 were detected by X-ray phase analysis in the sediments. It was established that at the initial concentration of iron ions of 26.6 g/dm3 with thermal activation of the reaction mixture and 16.6 g/dm3 with alternating magnetic fields activation, the sediment exclusively contains the magnetite phase. The results of the study indicate the possibility of further use of sediments for the production of important industrial products and materials containing ferromagnetic compounds. The implamitation of improved ferritization process in industrial enterprises will allow to achieve decrease of energy consumption compared to known technologies of exhausted etching solutions processing.
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