Mineral Powder Research Articles

Performance and microstructure of ultra-high-performance concrete (UHPC) with silica fume replaced by inert mineral powders

Ultra-high-performance concrete possesses extraordinary strength and durability. However, the high preparation cost of UHPC limits its large-scale engineering application. Recently, some studies have been done on the incorporation of granite powder (GP) in UHPC. It is reported that the granite powder possesses low pozzolanic activity and could replace part of quartz powder (QP) under autoclave curing. However, the silica fume (SF) would preferentially consume the Ca(OH)2 generated from the hydration to some extent, where the inert powder like granite powder or quartz powder could hardly participate in the pozzolanic activity due to low Ca(OH)2 content. In this research, the properties of UHPC incorporated by the silica fume and the inert powders like granite and quartz powder were studied, which are SF20, GP20A, GP20B, QP20A and QP20B respectively. Then the hydration products and microstructure of them were analyzed by the X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), Energy Dispersive Spectrometer (EDS), 29Si nuclear magnetic resonance (NMR), and Mercury intrusion porosimetry (MIP). Results demonstrated that the replacement of inert powders to SF greatly lowers the rheological parameters like shear stress and apparent viscosity, and improvs the flowability. And the sample SF20 possesses the highest mechanical strength due to its dense pore structure, of which the compact tobermorite was found in the products but few Ca(OH)2 was found. Besides, the compressive strengths of samples QP20A and QP20B were close to SF20 because their similar hydration products, pore size distribution and mean chain lengths (MCL). Due to the lower reaction activity of GP-A, the sample GP20A possessed the lowest strength but the highest pore diameter and porosity. While the grounded granite powder showed the higher reaction activity, resulting in the formation of tobermorite and a finer pore size distribution and the higher strength in GP20B. Hence, it can be concluded that the pozzolanic activity of inert powders, the quartz powder and the granite powder, could be greatly improved by autoclave curing and reducing the particle size. This study provides the theoretical basis for replacement for silica fume with inert powder and the possibility to reduce the preparation cost of UHPC and to enlarge its application.

Intelligent Localization Sampling System Based on Deep Learning and Image Processing Technology.

In this paper, deep learning and image processing technologies are combined, and an automatic sampling robot is proposed that can completely replace the manual method in the three-dimensional space when used for the autonomous location of sampling points. It can also achieve good localization accuracy, which solves the problems of the high labor intensity, low efficiency, and poor scientific accuracy of the manual sampling of mineral powder. To improve localization accuracy and eliminate non-linear image distortion due to wide-angle lenses, distortion correction was applied to the captured images. We solved the problem of low detection accuracy in some scenes of Single Shot MultiBox Detector (SSD) through data augmentation. A visual localization model has been established, and the image coordinates of the sampling point have been determined through color screening, image segmentation, and connected body feature screening, while coordinate conversion has been performed to complete the spatial localization of the sampling point, guiding the robot in performing accurate sampling. Field experiments were conducted to validate the intelligent sampling robot, which showed that the maximum visual positioning error of the robot is 36 mm in the x-direction and 24 mm in the y-direction, both of which meet the error range of less than or equal to 50 mm, and could meet the technical standards and requirements of industrial sampling localization accuracy.

Effect of Curing Regime on the Mechanical Strength, Hydration, and Microstructure of Ecological Ultrahigh-Performance Concrete (EUHPC).

This paper investigates the effect of curing regimes (standard and steam curing) on the mechanical strength, hydration, and microstructure of ecological ultrahigh-performance concrete (EUHPC). The flowability, compressive strength, flexural strength, hydration, porosity, pore size distribution, and microstructure of UHPC with different contents of supplementary materials (silica fume, fly ash, and ground granulated blast furnace slag) were assessed. The test results showed that the compressive strength of EUHPC under steam curing was increased considerably compared to that under standard curing, while the flexural strength was mildly decreased. The steam curing could decrease the porosity of EUHPC, which ranged between 7% and 9% for standard curing, and between 3.5% and 5% for steam curing. The aperture of EUHPC was below 20 nm, mainly located in the range of 10 nm to 20 nm under standard curing, while it was less than 10 nm for steam curing. C–S–H gel was produced under steam curing, while unhydrated fly ash, mineral powder, and Ca(OH)2 crystal were observed in the amorphous C–S–H gel. The microstructure of EUHPC under steam curing was denser than that under standard curing, and the interfacial transition zones under both curing regimes were compact.

МИНЕРАЛЬНЫЙ ПОРОШОК В СОВРЕМЕННОЙ СИСТЕМЕ ПРОЕКТИРОВАНИЯ АСФАЛЬТОБЕТОННЫХ СИСТЕМ

Within the framework of this article, the potential raw material base for obtaining mineral powders for the production of asphalt concrete mixtures is analyzed. The main stages of structure formation in asphalt concrete in the process of interaction of a bitumen binder with mineral materials are considered. Within the boundaries of modern approaches to the design of asphalt concrete mixtures, an assessment of the current regulatory framework is carried out in relation to the requirements for the indicators of the properties of mineral powders and the sampling methodology for assessing their quality. According to the research, despite the increased attention to the characteristics of mineral powders, the requirements for the methodological approach to sampling mineral powder and the quality assessment of the binary system "bituminous binder - mineral powder" or asphalt binder, which is the most significant component of asphalt concrete, is currently weak elaborated in the normative documentation. In the light of modern approaches to the design system of asphalt concrete mixtures, including the methodology of volumetric-functional design, it is of interest to develop a qualitative and quantitative assessment of the effect of mineral powders of different nature on the structuring of bituminous binders and, as a consequence, a change in their rheological properties.

Use of topical mineral powder as monotherapy for treatment of active peptic ulcer bleeding

The aim of this study was to evaluate the safety and effectiveness of Hemospray (Cook Medical, Winston-Salem, NC, USA), a hemostatic powder, as monotherapy for active peptic ulcer bleeding. In this prospective, multicenter, single-arm study, patients with Forrest Ia or Ib peptic ulcers underwent endoscopic application of Hemospray as treatment of first intent. Effectiveness endpoints were successful hemostasis at the end of the index endoscopy, recurrent bleeding within 72 hours and from 72 hours to 30 days, adverse events requiring reintervention or resulting in morbidity or mortality, and 30-day mortality. Hemospray was successfully administered in 98.5% of patients (66/67). Hemostasis was achieved at the index endoscopy in 90.9% of patients (60/66) with Hemospray alone and in an additional 4 patients treated with additional modalities, yielding an overall hemostasis rate of 97.0% (64/66). Rebleeding occurred in 13.3% of patients (8/60), 5 within 72 hours and 3 between 72 hours and 30 days. Two cases of perforation and 2 patient deaths occurred during the study, but none of these cases or any other adverse events were attributed to the use of Hemospray. The rate of early rebleeding was significantly higher in patients with Forrest Ia ulcers compared with patients with Forrest Ib ulcers. Higher rates of early bleeding in patients with Forrest Ia ulcers is consistent with results from studies where Hemospray was used as rescue after failure of conventional methods. Hemospray is an effective initial treatment for patients with active peptic ulcer bleeding, but care should be taken to monitor for recurrent bleeding. (Clinical trial registration number: NCT01306864.).

Aspects of Determining the Surface Activity of Dispersed Systems Based on Mineral Powders

Aspects of Determining the Surface Activity of Dispersed Systems Based on Mineral Powders

High Sulfate Resistance Portland Cement with Mineral Powder or Fly Ash in Marine Engineering: Effect of Nano-Silica on Structure and Properties and Mechanism Analysis Under Low-Calcium Conditions

High Sulfate Resistance Portland Cement with Mineral Powder or Fly Ash in Marine Engineering: Effect of Nano-Silica on Structure and Properties and Mechanism Analysis Under Low-Calcium Conditions

Features of determining the specific surface area of powdered quartz-containing systems

Introduction. Mineral raw materials, mechanically dispersed to a fine-grained condition, contribute to the effective use of the energy potential in the course of the structuring of composite materials. An important parameter, characterizing the dispersion ability and allowing to evaluate the ability of the system to transform is the specific surface of the substance. The experimental value of the specific surface depends on the measurement method and may differ for the same solids when different methods are applied. The purpose of the work is to study the morphological features of the surface of powdered quartz-containing systems having varying degrees of dispersion. The work represents the experimental identification of specific surface.
 Materials and methods. Filtration and adsorption methods were used to identify the specific surface of a mechanically activated sample of polymineral sand. Fine powders of sand were obtained by dry grinding in a planetary ball mill. The analysis of the obtained results was conducted taking into account the surface tension values of the powders as the characteristics of the surface energy of a surface area unit.
 Results. It is found that dimensions of the specific surface identified using the gas filtration method are smaller than those obtained using the nitrogen adsorption method. The authors have identified a linear functional dependence between the ratio of dispersion and polarization components of the surface tension and the ratio of specific surfaces obtained using different methods for one sample of sand.
 Conclusions. Despite a difference in the values obtained for the same material sample, specific surface area indicators, identified using different methods, allow to evaluate the extent of the surface maturity, the availability of active centres, and the energy potential of mineral powders. The ratio of specific surfaces can be used as a criterion for the rational choice of the operating parameters of mechanical activation of quartz-containing powder systems to increase the energy potential of the surface.

Influence of Ferronickel Slag on Impermeability of Seawater‐Corroded Cement Soil Using an Electrochemical Test

Since the traditional penetration testing of cement soil is time‐consuming, this paper introduces a new electrochemical testing method to study the effect of ferronickel slag powder on improving the impermeability of cement soil in the corrosive seawater environment. To this end, the mercury intrusion test was employed to analyze the change in the pore characteristics of cement soil, and the variation in the impermeability of cement soil was further explained from a microscopic point of view. The test results show that using the electrochemical method to test the impermeability of cement soil dramatically improves the efficiency of testing. The impermeability of cement soil gradually rises with an increase in its ferronickel slag powder content. Moreover, the optimal mass replacement ratio of the ferronickel slag powder and mineral powder composite to cement is 40% in the testing range of 0–40%. The mercury intrusion test results also confirm that the addition of ferronickel slag powder can decrease the most probable pore size and total porosity of cement soil; further, from a microscopic perspective, the ferronickel slag powder can help reduce the corrosion of cement soil by seawater. The above test conclusions are consistent with the results of the traditional permeability test. Our findings not only imply that ferronickel slag powder can lessen the effect of seawater on the corrosion of cement soil but prove that the electrochemical test is a reliable and straightforward method for determining the impermeability of cement soil.

Green Hydrogels Composed of Sodium Mannuronate/Guluronate, Gelatin and Biointeractive Calcium Silicates/Dicalcium Phosphate Dihydrate Designed for Oral Bone Defects Regeneration.

Innovative green, eco-friendly, and biologically derived hydrogels for non-load bearing bone sites were conceived and produced. Natural polysaccharides (copolymers of sodium D-mannuronate and L-guluronate) with natural polypeptides (gelatin) and bioactive mineral fillers (calcium silicates CaSi and dicalcium phosphate dihydrate DCPD) were used to obtain eco-sustainable biomaterials for oral bone defects. Three PP-x:y formulations were prepared (PP-16:16, PP-33:22, and PP-31:31), where PP represents the polysaccharide/polypeptide matrix and x and y represent the weight % of CaSi and DCPD, respectively. Hydrogels were tested for their chemical-physical properties (calcium release and alkalizing activity in deionized water, porosity, solubility, water sorption, radiopacity), surface microchemistry and micromorphology, apatite nucleation in HBSS by ESEM-EDX, FT-Raman, and micro-Raman spectroscopies. The expression of vascular (CD31) and osteogenic (alkaline phosphatase ALP and osteocalcin OCN) markers by mesenchymal stem cells (MSCs) derived from human vascular walls, cultured in direct contact with hydrogels or with 10% of extracts was analysed. All mineral-filled hydrogels, in particular PP-31:31 and PP-33:22, released Calcium ions and alkalized the soaking water for three days. Calcium ion leakage was high at all the endpoints (3 h–28 d), while pH values were high at 3 h–3 d and then significantly decreased after seven days (p < 0.05). Porosity, solubility, and water sorption were higher for PP-31:31 (p < 0.05). The ESEM of fresh samples showed a compact structure with a few pores containing small mineral granules agglomerated in some areas (size 5–20 microns). PP-CTRL degraded after 1–2 weeks in HBSS. EDX spectroscopy revealed constitutional compounds and elements of the hydrogel (C, O, N, and S) and of the mineral powders (Ca, Si and P). After 28 days in HBSS, the mineral-filled hydrogels revealed a more porous structure, partially covered with a thicker mineral layer on PP-31:31. EDX analyses of the mineral coating showed Ca and P, and Raman revealed the presence of B-type carbonated apatite and calcite. MSCs cultured in contact with mineral-filled hydrogels revealed the expression of genes related to vascular (CD31) and osteogenic (mainly OCN) differentiation. Lower gene expression was found when cells were cultured with extracts added to the culture medium. The incorporation of biointeractive mineral powders in a green bio-derived algae-based matrix allowed to produce bioactive porous hydrogels able to release biologically relevant ions and create a suitable micro-environment for stem cells, resulting in interesting materials for bone regeneration and healing in oral bone defects.

Gel permeation chromatography-based method for assessing the properties of binders in reclaimed asphalt pavement mixtures

Evaluating the properties of asphalt in reclaimed asphalt mixture (RAP) is a crucial step in the design of hot recycled mixtures. The conventional assessment approach involves the extraction and recovery of the aged asphalt with further assessing the aging condition of recovered binders via their penetration, viscosity, and performance-related properties. Since this approach is time-consuming, environmentally unfriendly and involve residue mineral powders that may alter the recovered binder properties, an alternative gel permeation chromatography-based method, requiring no extraction or recovery, was proposed in this study. The gel permeation chromatography (GPC) test were carried out to directly analyze the Large molecular size (LMS) content of unrecovered binders in asphalt mixture samples under different aging conditions, which were prepared via laboratory simulated aging procedure. LMS content was found sensitive in reflecting the aging condition for the binders in the mixture. In addition, the correlation between the aging levels of asphalt mixtures aged under laboratory conditions with those of single asphalt samples was established. Following this, the best-fit regression model linking the LMS content in a mixture sample with the rutting factor, penetration and viscosity were developed. According to the above regression model, the conventional properties of RAP binders were predicted by their LMS content, which can be further applied to assess the aging condition of RAP binders, eliminating the complicated extraction and recovery process. Three sources of on-site RAPs verified the proposed method feasibility: it reasonably estimates the properties of binders in RAP, especially for base asphalt.

Evaluation of interaction between emulsified asphalt and mineral powder using rheology

Polymer emulsion can significantly improve the performance of emulsified asphalt but can also increase the complexity of the system, especially after mixing with mineral powder. The objective of this study was to evaluate the emulsified asphalt and mineral powder interaction ability based on rheological properties. First, two types of emulsified asphalt and three types of mineral powders were selected to prepare emulsified asphalt residues and mastics, and their dynamic shear rheological (DSR) properties were measured. Second, the K-B-G* and ΔG* models were used to evaluate the influence of temperature and loading frequency on emulsified asphalt and mineral powder interaction ability. Third, the physicochemical interaction between the emulsified asphalt and mineral powder was measured by a Fourier transform infrared (FTIR) spectrometer. Finally, the significance analysis of temperature and loading frequency was conducted by grey relational analysis (GRA). The mold designed in this study was demonstrated effective in obtaining emulsified asphalt residue samples that were suitable for DSR tests at low temperature. K-B-G* and ΔG* indices are consistent in evaluating the interaction ability between emulsified asphalt and mineral powder. The two indices can reflect the influences of temperature and frequency on emulsified asphalt and mineral powder interaction ability, and they also can reflect the difference in the interaction ability of different mineral powders and emulsified asphalt. No new absorption peak in the FTIR spectrum indicated that the physical interaction between emulsified asphalt and mineral powder is primarily the physical action. GRA can be applied to the significance analysis of temperature and loading frequency, and the temperature demonstrates greater influence than the loading frequency. The cationic emulsifier plays the role of anti-stripping agent and enhances the interaction between cationic emulsified asphalt and acid aggregate. The rheological results can guide the selection of the appropriate emulsifier according to the aggregate using in the project.

Application of Phosphogypsum in Road Construction

Abstract. Currently the Republic of Belarus is solving the problem of processing a by-product – phosphogypsum, formed in the process of phosphorric acid production. The issue of utilization of phosphogypsum is becoming more and more relevant, and there are several reasons for this: transportation of phosphogypsum to dumps and its storage require large capital investments and operating costs; when creating phosphogypsum dumps, it is necessary to alienate large areas, sometimes even cultivated land; storage of this material in dumps, even with the neutralization of soluble impurities and with the observance of dump operational rules causes irreparable harm to the environment. There are known studies of scientists on the use of phosphogypsum for road construction as a binder for strengthening soils, foundations and repair work. The paper presents the results of experiments on obtaining road-building materials from this waste without converting it into a binder. Based on the research, a technology for the preparation of asphalt concrete mixtures with the use of mineral powder in the form of phosphogypsum dihydrate has been developed.

Reasons for Reduced Moisture Resistance of Sulfur-Extended Asphalt Concrete.

The paper presents the results of a study of the mechanism for reducing the moisture resistance of sulfur-extended asphalt concrete. It is shown that a decrease in moisture resistance occurs due to the occurrence of chemical and physical processes. At the same time, it was found that during the manufacture of sulfur-bitumen composites, toxic gases H2S and SO2 are formed, which are capable of interacting with a mineral filler, as well as the interaction of sulfur with a mineral powder with the formation of sulfur-containing water-soluble salts, the extraction of which leads to a decrease in the moisture resistance of sulfur-bitumen materials. The change in the rate of leaching of these substances from the composite is due to the physical process caused by the crystallization of sulfur and the formation of a capillary structure, which significantly increases the rate of leaching of calcium and magnesium salts, which are products of dissolution or hydrolytic decomposition of water-soluble products of the interaction of sulfur, H2S and SO2 gases with calcium and magnesium carbonates. The intensity of chemical and physical processes intensifies with an increase in the amount of sulfur in sulfur-bitumen materials.

Molecular mechanism of increasing extracellular polysaccharide production of Paenibacillus mucilaginosus K02 by adding mineral powders

Bacterial polysaccharides are widely applied in a range of products and increasing bacterial polysaccharide production is important commercially. In this study, attapulgite, serpentine, talc, biotite, and hydroxylapatite were used to stimulate extracellular polysaccharide (EPS) production by Paenibacillus mucilaginosus K02. The viscosity, polysaccharides, and proteins in culture medium in shaking flasks were quantified after addition of different minerals to the culture medium, and the molecular mechanism of serpentine on stimulating bacterial EPS synthesis was further revealed by proteomic and metabolomic analysis. The results showed that the viscosity, EPS, and protein contents in the culture were significantly increased by the introduction of minerals. The underlying mechanism for increased EPS production was due to a series of protective strategies of the bacterium against the damage arising from collision and friction caused by mineral powders. That is, bacteria protect and maintain their normal life by synthesis and secretion of excessive EPS, enhancement of oxidation resistance and secretion of various organic acids under these mineral treatments. The results not only show the importance of polysaccharide production for bacteria survival under adverse conditions, but also provide a new way of increasing bacterial production of more EPSs.

Study on Mix Proportion Optimization of C50 High Strength Concrete

With the progress of engineering technology, C50 high-strength coagulation came into being for the needs of actual engineering. This research mainly focuses on the selection of cement varieties and admixtures of C 50 high-strength concrete, so as to realize the optimization research of the mix ratio of C 50 high-strength concrete. The results show that ordinary P.O 42.5 and fly ash admixture can increase the mechanical performance of concrete. However, the concrete compressive strength with the mixed admixture of fly ash and mineral powder is even lower than that without any admixture. On the premise of meeting actual engineering needs, the optimization of the mix ratio of high-strength concrete can not only achieve sustainable development, but also save investment in project economic costs.

ВИКОРИСТАННЯ ПОБІЧНИХ ВІДХОДІВ ПРОМИСЛОВОСТІ В ЯКОСТІ МІНЕРАЛЬНОГО ПОРОШКУ В ДОРОЖНЬОМУ БУДІВНИЦТВІ

Introduction. Mineral powder is an important structural component of asphalt concrete. Mineral powder is the output material obtained after crushing of rocks or powdery remains of the industry. It is made by grinding the following hard rocks: dolomitized limestone, dolomite, limestone. Non-carbonate raw materials and industrial wastes are also used as raw materials. Problem statement. Road construction with the arrangement of asphalt concrete pavements requires a number of components of these mixtures. Due to this, the need in scarce carbonate mineral powders is growing. Therefore, it is advisable to consider researches directed on studying a number of by-products of industry in order to use them as a mineral powder of asphalt concrete. Purpose. To analyze the existing experience of using industrial waste as a mineral powder in production of asphalt concrete mixture for further introduction and improvement of environmental safety and operational characteristics of pavement due to new road construction materials. Materials and methods. Analysis of information sources and experience in the use of industrial waste as a mineral powder and study of requirements for materials and their composition. Results. An analytical review of the experience of using industrial waste as a mineral powder was performed. Various materials have been studied and analyzed, requirements for materials, their particle size distribution, content in asphalt concrete mixture had been established. Conclusions. Analysis of information sources regarding use of industrial waste as a raw material for the production of mineral powder had determined that they are used in the whole volume in different countries and in most cases in road construction. It had been found that the use of various wastes during road construction is a viable option that needs further study.

Research on vehicle-asphalt pavement interaction and micro-structure by discrete element method

Asphalt mixture is composed of coarse aggregate, fine aggregate, mineral powder, asphalt, etc., with heterogeneous, discontinuous characteristics. The mechanical behavior of asphalt mixture particles under vehicle load is very complicated. And the asphalt pavement will be damaged in the early bearing stage, which is closely related to the mechanical behavior between the particles of the mixture. In order to study the mechanical response of asphalt mixture particles under vehicle load, a 2 DOF (degrees of freedom) 1/4 vehicle model composed of mass block–spring-damper was constructed in this paper. In this model, the mechanical response and velocity of particles in pavement structure layer are solved by programming. The results show that the vertical displacement of the pavement calculated by the discrete element method is less than 8.9% of that calculated by the finite element method, which indicates that the discrete element method is more feasible.

Study on the Durability of Concrete under an Underwater Coupling Environment

The durability of the concrete structure under the coupling effect of underwater corrosion particles has always been one of the hot issues at home and abroad. Aiming at the damage problem of the underground concrete structure in a marine and offshore chloride corrosion environment, based on the pile foundation engineering of the Coastal Industrial Park, the corrosion resistance test of pile foundation concrete is carried out. By preparing 7 kinds of pile foundation concrete samples with different mix proportions, the mechanical properties of concrete with different ages were analyzed under the coupling environment of groundwater. The chloride penetration resistance of concrete was analyzed by the RCM method, and the sulfate corrosion resistance was analyzed by the 17D accelerated simulation test. The test results show that with the decrease of the water-cement ratio and the increase of the cementitious material, the concrete damage is less and the durability is improved. It is suggested that the water-cement ratio of 0.34 and the cementitious material of 480 kg/m3 be selected for the preparation of the pile foundation concrete; when the content of fly ash is 15%, the antisulfuric acid corrosion ability of the concrete cementitious system can be enhanced and the concrete with 40% mineral powder has strong antichloride ion corrosion ability; the results show that the chloride diffusion coefficient of concrete samples with seven mix proportions is less than 6 ∗ 10–12 m2/s, which can meet the durability design requirements and reduce the damage of concrete. The sulfate corrosion resistance of concrete samples with high-efficiency additives is the best.

Collaborative disposal of multisource solid waste: Influence of an admixture on the properties, pore structure and durability of foam concrete

Solid waste building material treatment is an essential means of disposal and an active research area. Despite this, the multisource characteristics, large volumes and complex compositions of solid waste necessitate new requirements for its treatment. In this paper, a typical resource-based coastal city is considered the research object. Fly ash (FA), furnace slag (FS) and mineral powder (MP) are taken as samples to investigate the influence of admixtures on the properties, pore structure and durability of foam concrete by three-factor and three-level orthogonal tests. Results indicate that foam concrete with different admixtures can have various mechanical and thermal insulation properties. The compressive strength of foam concrete can increase to 3.90 MPa, and its thermal conductivity can reach 0.1347 W/M·k. MP has the largest apparent effect on the compressive strength, while FS has the most obvious impact on the thermal conductivity. The durability analysis shows that the number of freeze-thaw cycles foam concrete can withstand is 25–100 cycles. The collaborative disposal of multisource inorganic solid waste has high potential for being applied as inner partition walls and thermal insulating components in buildings. This paper provides valuable guidance for the sustainable and clean utilization of multisource inorganic solid waste.