Hollow Beads Research Articles

Exploring the synthesis effects of glazed hollow beads and polypropylene fibers on the strength retention of ultra-high performance concrete after fire exposure using X-Ray computed tomography

Ultra-high performance concrete (UHPC) is a cementitious composite characterized by its ultra-high durability attributes and mechanical properties. It is primarily used in large-span and ultra-high-rise structures for control of deflections. However, its mechanical properties decrease significantly after exposure to fire or high temperatures, limiting its applicability. In this paper, the exceptional characteristics of glazed hollow beads (GHBs), including their lightweight, high strength, and thermal insulating properties, were utilized to develop a novel fire-resistant UHPC. UHPC specimens with varying GHB content were prepared, and the corresponding mass loss, thermal performance degradation, and compressive strength after exposure to high temperatures were evaluated. The test results demonstrate that adding GHBs can improve the fire resistance of UHPC. With 40 % (by volume) GHB addition, the resulting UHPC could retain 47 % of its original compressive strength even after exposed to 800°C. The effects of temperature on the UHPC microstructure were analyzed using scanning electron microscopy and X-ray computed tomography. It was found that the combination of polypropylene fibers and GHBs created a release channel for vapor pressure within the concrete, thereby enhancing its high-temperature resistance. This study proposes a practical solution to enhance the high-temperature resistance of UHPC.

Experimental Investigation on the Acoustic Insulation Properties of Filled Paper Honeycomb-Core Wallboards.

Honeycomb plates, due to their multi-cavity structure, exhibit excellent mechanical properties and sound insulation. Previous studies have demonstrated that altering the cell size and arrangement of honeycomb structures impacts their acoustic performance. Based on these findings, this study developed a wallboard structure with enhanced sound insulation by filling the cavities with paper fiber/cement facesheets and designing a stacked core structure. Through the reverberation chamber-anechoic chamber sound insulation experiment under 100-6300 Hz excitation and conducting orthogonal experiments from three dimensions, it was found that: (1) Compared to no filling, the filling with straw and glazed hollow bead can increase the sound transmission loss (STL) by more than 50% in the frequency bandwidth above 2000 Hz. This indicates that both types of fillings can significantly enhance the sound insulation performance of the honeycomb structure without a significant increase in economic costs. (2) The increase in paper fiber/cement facesheets improves the STL across the entire experimental bandwidth, with a maximum improvement exceeding 70%. This structural design not only offers superior sound insulation performance but also better suits practical engineering applications. (3) Increasing the number of core stacking units (from one to three), taking straw-filled paper honeycomb-core wallboards as an example, effectively increased the STL bandwidth. (4) This test enriches the application of honeycomb plates in sound insulation. Introducing fiber paper fiber/cement facesheets and eco-friendly, low-cost straw improves sound insulation and enhances the strength of honeycomb, making them more suitable for construction, particularly as non-load-bearing structures.

Study on the properties and mechanisms of the glazed hollow bead thermal insulation mortar

With increasing concerns for energy conservation and environmental protection, research on glazed hollow bead thermal insulation mortar is of utmost importance. This type of mortar offers superior thermal insulation, leading to reduced energy consumption and emissions, in line with the current green building trends. This article aims to investigate the impact of varying component proportions on the parameters of thermal insulation mortar through an orthogonal experiment with four factors and three levels: glazed hollow bead, sepiolite, air-entraining agent, and cellulose ether. Additionally, a single-factor experiment is conducted to analyze the influence degree of water-solid ratio and these four factors. The experimental results are then verified through SEM (Scanning Electron Microscope) observation. The research findings indicate that glazed hollow beads have the most significant impact on thermal conductivity and compressive strength, while the air-entraining agent exerts the greatest influence on flexural strength. Specifically, when the content of glazed hollow bead is 2%, sepiolite 1%, air-entraining agent 0.6%, and cellulose ether 0.6%, the thermal conductivity can reach a minimum value of 0.0533W/(m·K). On the other hand, when the content of glazed hollow bead is 1%, sepiolite 2%, air-entraining agent 0.4%, and cellulose ether 0.6%, the compressive strength can achieve a maximum value of 2.4 MPa. These findings provide a solid foundation for further exploration into improving the performance of thermal insulation mortar.

Enhancing chloride ion permeability resistance of recycled aggregate concrete through internal curing with glazed hollow beads

This study explores the effects of glazed hollow beads (GHB) dosage and additional water amount on the capillary negative pressure, mechanical properties, initial resistivity, and electric flux in conditions where recycled aggregate concrete (RAC) is subject to cracking. The chloride ion (Cl-) diffusion coefficient for RAC cured internally was evaluated using the resistivity method, which also looked at the relationship between the diffusion coefficient, GHB dosage, and additional water amount. This analysis advances our understanding of the functional mechanisms of pre-soaked GHB in RAC. The research reveals that incorporating pre-soaked GHB enhances RAC in two primary ways. Firstly, pre-soaked GHB acts as an internal curing agent that stimulates the formation of hydration products, thereby filling internal voids and mitigating micro-crack development. Secondly, it functions as an adsorbent. The differential in relative humidity and internal pressure between the unsaturated GHB and the cement stone matrix promotes the sequestration of corrosive agents in cracked RAC. Additionally, an internal curing impact factor has been introduced, forming the basis of a new model to calculate the Cl- diffusion coefficient that accounts for both GHB dosage and additional water intake. The established quantitative relationships between resistivity, electric flux, and Cl- diffusion coefficient in GHB-treated RAC (GHB-RAC) provide a methodological framework for quickly evaluating the durability of GHB-RAC against Cl- intrusion in practical engineering contexts.

Durability and thermal insulation properties of glazed hollow bead concrete with nanoparticles in marine atmospheric environment

Industrial and civil buildings in coastal areas have been in the marine atmosphere for a long time and are especially susceptible to the combined effects of carbonation and salt spray, which accelerate the deterioration of concrete durability and the reduction of thermal insulation performance. This paper focused on the effect of nano-SiO2 and nano-Al2O3 on the durability and thermal insulation of glazed hollow bead concrete (GC) under a salt spray carbonation environment, and analyzed the mechanism of nanoparticles on the improvement of durability and thermal insulation of GC by means of scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD) microscopic tests. The results showed that both nano-SiO2 and nano-Al2O3 incorporation could improve the durability and thermal insulation of GC to a certain extent. The optimal amount of both nanoparticles was 2 %, and nano-SiO2 had a stronger beneficial effect than nano-Al2O3. In comparison to GC, the free Cl− content in the surface layer of GCNS20 and GCNA20 after 56 cycles was decreased by 33.33 % and 27.22 %, respectively. Furthermore, the carbonation depths of GCNS20 and GCNA20 were decreased by 42.83 % and 36.38 %, respectively. The thermal conductivity of GCNS20 and GCNA20 decreased by 24.86 % and 17.34 %, respectively, while the thermal diffusion coefficients were reduced by 33.22 % and 23.73 %, respectively. The incorporation of nanoparticles effectively reduced the microcracks and pores in GC, improved its internal structure, and reduced the possibility of thermal bridge formation. In addition, the incorporation of nanoparticles significantly reduced the production of erosion products such as CaCO3 and Friedel's salt in GC.

Feasibility of natural bamboo branches aggregate applied to the thermal insulation layer of rock walls in roadways

The high-temperature heat damage is mainly caused by heat dissipation of surrounding rock in deep mining of mine, so spraying thermal insulation layer (TIL) on mine roadway can be used to actively heat insulation. As a kind of green material, bamboo branches have excellent thermal insulation and mechanical properties. In this paper, gravel and ceramsite were used as aggregate, bamboo branches and glass hollow bead were used as main thermal insulation materials, and the effects of different content, diameter, and length of bamboo branches on mechanical properties, thermal insulation properties, and microstructure were studied through orthogonal experiments. A group of specimens with the best comprehensive performance was selected through the analysis of the efficiency coefficient, and the optimal ratio was determined. This ratio ensures the perfect balance between insulation and strength for TIL, which is essential for the preparation of TIL. At the same time, the numerical simulation software Fluent was used to establish the roadway model, and the cooling effect of the TIL on the airflow temperature in the roadway under different working conditions was studied based on the parameters of the selected specimens. These parameters are based on the actual characteristics of the specimen, and their accuracy ensures the reliability and validity of the research results. The results show that under the optimal mixing ratio, the thermal conductivity (TC) of the specimen is 0.224 W/(m·K), the thermal insulation performance of the prepared coating is increased by 25∼65 %, and the mechanical strength is also improved. The optimal mix ratio obtained in this study can be applied to the field of mine thermal damage control, and the feasibility of natural bamboo branches for preparing roadway thermal insulation material is demonstrated. Bamboo branches grow rapidly, and their use as thermal insulation materials will not only not cause a burden on the environment, but help to promote ecological recycling and achieve sustainable use of resources.

Experimental study on creep characteristics of glazed hollow beads-cement/sodium silicate grouting materials

This study introduces a new thermal insulation grouting material designed for high-temperature mine environment. The thermal insulation effect of cement/sodium silicate grouting materials can be enhanced by adding glazed hollow beads with outstanding thermal insulation properties. The ratio with the best comprehensive performance was selected through orthogonal tests, and the long-term creep mechanical characteristics of glazed hollow beads-cement/sodium silicate grouting materials were analyzed. Graded equal incremental loading with different loading durations was used to test the specimens' instantaneous strain, creep strain, creep rate, critical stress, and microscopic structures. For each loading stage, the Burgers model was used to fit the creep curve. The results show that graded loading intensity surpasses uniaxial loading across different loading durations. The different loading durations significantly affect the creep parameters, and stress concentration damage initially manifests on the surface of glazed hollow beads. Finally, the theoretical curve obtained by the Burgers model fits well with the creep test curve. This study has good practical significance for high-temperature roadway thermal grouting insulation technology.

Mechanical properties and damage characteristics analysis on recycled aggregate concrete with glazed hollow beads after high temperatures by acoustic emission method

This research investigates the effect of high temperature on the mechanical and acoustic emission properties of recycled aggregate concrete with glazed hollow beads (GHB-RAC). Uniaxial compression tests were conducted on GHB-RAC at varying recycled coarse aggregate (RCA) substitution rates and glazed hollow beads (GHB) contents, and acoustic emission (AE) technology was used to monitor the compression-induced damage throughout the testing process. This study delves into the mechanical properties and damage characteristics of GHB-RAC when exposed to fire. The findings reveal that AE characteristic coefficients aptly delineate the three-stage nature of axial compression damage in concrete at temperatures up to 400 °C. However, these stage-specific traits vanish at temperatures exceeding 400 °C. Additionally, through the analysis of AE signals at different temperatures, the compression damage process is elucidated based on the b-value method. The RA-AF analysis indicates that the number of shear cracks exhibits an increasing trend with increasing temperature, and an increment in GHB dosage positively influences the percentage of tensile cracking during loading, with the influence being more significant at 70 % GHB content. The acoustic emission sensing can accurately detect and localise damage. With the increase in temperature, the distribution of AE signals depicting concrete damage is more dispersed and the number of AE signals is more larger. Notably, the incidence of localized damage points diminishes with a higher GHB ratio, indicating the efficacy of GHBs in mitigating thermal damage to the concrete. Furthermore, a damage constitutive model incorporating variables such as temperature, GHB dosage, and recycled coarse aggregate replacement rate was proposed. The model employed AE energy count parameters as the damage indicator. The good fitting results suggest that the mechanics behavior of GHB-RAC under uniaxial compression can be well described by the model. Consequently, the study offers invaluable insights into the damage evolution of post-fire recycled aggregate concrete with GHB admixtures.

Mechanical Properties and Failure Behavior of Epoxy Rubber Powder Composites Reinforced with Hollow Beads

In this paper, new epoxy resin/rubber powder/hollow beads three-phase composites were prepared by designing the incorporation of fly ash hollow beads with different mass fractions (5%, 10%, 15%, and 20%) as new reinforcing phases into epoxy resin/rubber powder two-phase composites with 5% mass fraction of carbon black rubber powder. Quasi-static compression tests were conducted at room temperature to test the compressive properties of the oxygen resin/rubber powder/hollow beads composites. Calculate the energy absorption properties and energy absorption efficiency of the composites from the compression curves. Fracture characteristics of compressed material specimens with microscopic morphology were observed by scanning electron microscopy. By systematically analyzing the effect of fly ash hollow beads content on the mechanical properties of epoxy resin/rubber powder/hollow beads three-phase composites, it was found that fly ash hollow beads as reinforcing materials can effectively improve the brittleness and yield strength of epoxy resin/rubber powder as well as the energy-absorbing properties and efficiency of the composites. The energy absorption properties of the epoxy resin/rubber powder/hollow beads composites increased and then decreased with the increase in the mass fraction of fly ash hollow beads. In the epoxy resin/rubber powder/hollow beads composites, the most significant performance was observed when the mass fraction of fly ash was 10%.

Tungsten oxide encapsulated phosphate-rich porous alginate composites for efficient U(VI) capture: Insights into synthesis, adsorption kinetics and thermodynamics

In this work, novel monoclinic tungsten oxide (WO3)-encapsulated phosphate-rich porous sodium alginate (PASA) microspherical hydrogel beads were prepared for efficient U(VI) capture. These macroporous and hollow beads were systematically characterized through XRD, FTIR, EDX-mapping, and SEM-EDS techniques. The O and P atoms in the PO and monoclinic WO3 offered inner-spherical complexation with U(VI). The in situ growth of WO3 played a significant role inside the phosphate-rich biopolymeric network to improve its chemical stability, specific surface area, adsorption capacity, and sorption rate. The phytic acid (PA) served for heteroatom doping and crosslinking. The encapsulated WO3 mass ratio was optimized in different composites, and WO3/PASA3 (the microspherical beads with a mass ratio of 30.0 % w/w) exhibited remarkable maximum sorption capacity qm (336.42 mg/g) computed through the best-fit Langmuir model (R2 ≈ 0.99) and rapid sorption equilibrium, teq (150 min). The isothermal sorption studies were conducted at different temperatures (298, 303, and 308 K) and thermodynamic parameters concluded that the process of U(VI) sorption using WO3/PASA3 is endothermic and feasible having ΔHo (8.19 kJ/mol), ΔGo (−20.75, −21.38, and − 21.86 kJ/mol) and proceeds with a minute increase in randomness ΔSo (0.09 kJ/mol.K). Tungsten oxide (WO3)-encapsulated phosphate-rich porous microspherical beads could be promising material for uranium removal.

The effect of circumference on the segregation of objects in a mixture

The size segregation problem refers to the phenomena of larger particles rising to the top of a mixture of variously sized items seemingly against gravity. Upon reviewing the literature on the size-segregation problem, also known as the trail mix quandary, we realized that the reported findings did not account for the apparent adverse behavior of hollow items. Despite geophysical implications, such as erosion sediments, explanations regarding hollow items are necessary to ensure more precise distribution of nanoparticle substances throughout various systems. Additionally, the size segregation of irregularly shaped particles has not been clearly addressed. To address these limitations, we put forth a hypothesis that circumference, rather than size, dictates the arrangement of falling objects. We found that the distribution of hollow particles could be better predicted with a revision of the size-segregation theory. The key observation that motivated us to propose the revision to the model was that hollow beads sometimes trended toward the bottom of the mixing container over their smaller counterparts, contrary to the size-segregation theory. Our findings may increase precision and predictability of particle movement of non-enclosed hollow objects among unrelated items. A better understanding of particle distribution that may explain certain phenomena (i.e., that larger particles tend to rise to the top of a mixture and not sink under the influence of gravity) could be useful for many fields that deal with particulate matter from geology to chemistry.

Research on Damage Evolution Law of Glazed Hollow Beads-Cement/Sodium Silicate Grouting Materials under Different Cycles of Loading and Unloading.

With the depletion of shallow resources, deep resource mining has become a trend. However, the high temperature and complex stress environment in deep mines make resource extraction extremely challenging. This paper developed a thermal insulation grouting material made of glazed hollow beads, sodium silicate, and cement and tested the compressive strength, gelation time, and stone rate under various curing days in light of the issue of high temperature heat damage in high ground temperature mines and the impact of mining on roadway grouting bolt support. Fatigue strength, fatigue deformation, load-residual strain, energy evolution and microscopic features were studied and analyzed in relation to the damage law of graded cyclic loading and unloading under the number of varying cycles. The findings demonstrate that cyclic loading and unloading strength is lower than uniaxial compressive strength. The fatigue strength is significantly decreased when the number of cycles reaches its limit. Residual strain is less sensitive to changes in stress than load strain. The fitting correlation coefficients of total output energy and elastic energy are higher than 0.71.

Preparation of lightweight polycarbonate composite foams with robust hollow glass microspheres via CO2 foaming

AbstractPolycarbonate (PC) composites are often used in the production of high value‐added products, but it is necessary to improve its environment stress cracking condition in the presence of pre‐strain and soluble solvents. In this work, the effect of weight reduction and strengthening is realized by introducing microstructures and hollow glass microspheres (HGMs) into the PC composites. It is found that the addition of HGMs can reduce the melt viscosity and Tg value of the composite materials, which will change the foaming behavior of PC/HGMs composites. Besides, the effect of different content of HGMS and foaming temperature on the foaming behavior of PC/HGMs composite foams are studied. The PC/HGMs composite foams exhibit a typical structure of both large and small cellular pores, because of the existence of hollow beads and cellular structures. Moreover, compared to the neat PC foam, the tensile strength as well as the flexural strength of the composite foams are significantly increased by 110.9% and 364.7%, respectively. Furthermore, the as‐prepared PC/HGMs composite foams have low thermal conductivity (lower than 0.07 W/mK), which can effectively insulate heat propagation.Highlights Hollow glass microsphere can reduce melt viscosity and Tg of composites. The mechanical properties of composite foams have been greatly improved. Composite foams exhibit excellent thermal stability due to their microstructure.

Research on Glazed Hollow Bead Insulation concrete freezing process with different saturation based on nuclear magnetic resonance

This paper uses experimental analysis to understand the freezing law of water to determine the freezing damage mechanism of Glazed Hollow Bead Insulation Concrete (GIC). The critical saturations of GIC with different Glazed Hollow Beads (GHBs) contents were obtained by the relative moving modulus after testing seven saturations of the concrete (70% to 100%, 5% interval). The critical saturation of GIC-0 (i.e., 0% GHBs content) occurred at ∼ 76–78%. GIC-50 occurred at about 86–88%. GIC-100 occurred at about 89–91%. GIC-0, GIC-50, and GIC-100 were then saturated to S60, Scr, and S100 based on their respective critical saturation. Low-field nuclear magnetic resonance (NMR) was used to study the freezing process of different water types in GIC. The results showed that: 1) The water inside GIC was composed of adsorb water, pore water, and free water; 2) The whole freezing process could be roughly divided into four stages: subcooling stage, rapid freezing stage, stable freezing stage, and the end of the freezing phase; 3) During the freezing and thawing process, the change in unfrozen water content of GIC specimens had a hysteresis curve, while the specimens less than the critical saturation had almost no hysteresis curve. Moreover, the saturation significantly influenced the freezing process of different water types, which determined the proportion of them. This study also determined the evolution of the pore size of GIC, which provides a new idea for analyzing the freezing damage mechanism of porous GIC.

Large-scale hollow-core 3D printing (HC3DP): A polymer 3D printing technology for large-scale ultralightweight components

Material extrusion (ME) has become a popular 3D printing method for large-scale applications such as in the automotive, naval, aerospace, and architecture sectors. It allows the production of complex, customized parts without the need of labour-intensive molds. The increasing need to produce larger and larger parts has been addressed with the introduction of large pellet extrusion systems to increase the extrusion rate. With these extruders the production time is not limited by the extrusion rate of the extruder (kg/h) but by the time the material needs to cool down before the next layer can be printed consecutively. Furthermore, larger bead dimensions result in increased material usage and, therefore, might affect the environmental impact of the printed element. In this study, a method for large extrusion 3D printing based on hollow beads is proposed, to address the limitations of speed, cooldown and maximize the extrusion rate of thermoplastic 3D printing. This paper introduces Hollow-Core 3D printing (HC3DP) and compares it to off-the shelf large-scale pellet extruders and their maximum achievable extrusion rate for a given geometry. A comparative analysis of cooldown characteristics between conventional thermoplastic extrusion 3D printing and HC3DP validates that the latter increases the maximum possible extrusion rate. Additionally, the successful 3D printing of large-scale beads with multiple polymer feedstocks is demonstrated. Then the data associated with printing speed and material usage is presented and discussed in comparison with thermoplastic and other large-scale 3D printing methods. The fabrication of large-scale hollow-core beads at a dimension of 24×20mm is showcased with an extrusion rate of 7250 mm3/s (1308 material, 5941 air). HC3DP for large-scale applications is validated through the production of 2-meter tall cylinders with a diameter of 400 mm in less than two hours. Furthermore, bespoke die geometries that subdivide the inside of hollow 3D-printed beads are presented. To successfully print those, the concept of differentiated internal air pressure per print point is introduced. Finally, 3PT bending tests are conducted to compare different die geometries. In conclusion, this study presents a printing method that highlights the benefits of hollow core 3D printing for large-scale applications, showcasing its positive impact on both the printing process and resulting part properties. By addressing the limitations of traditional approaches, HC3DP pushes polymer 3D printing into a scale relevant for architecture and construction, offering similar extrusion rates as concrete 3DP.

Immobilization of Rhodococcus by encapsulation and entrapment: a green solution to bitter citrus by-products.

Debittering of citrus by-products is required to obtain value-added compounds for application in the food industry (e.g., dietary fiber, bioactive compounds). In this work, the immobilization of Rhodococcus fascians cells by encapsulation in Ca-alginate hollow beads and entrapment in poly(vinyl alcohol)/polyethylene glycol (PVA/PEG) cryogels was studied as an alternative to chemical treatments for degrading the bitter compound limonin. Previously, the Rhodococcus strain was adapted using orange peel extract to increase its tolerance to limonoids. The optimal conditions for the encapsulation of microbial cells were 2% Na-alginate, 4% CaCl2, 4% carboxymethylcellulose (CMC), and a microbial load of 0.6 OD600 (optical density at 600nm). For immobilization by entrapment, the optimal conditions were 8% PVA, 8% PEG, and 0.6 OD600 microbial load. Immobilization by entrapment protected microbial cells better than encapsulation against the citrus medium stress conditions (acid pH and composition). Thus, under optimal immobilization conditions, limonin degradation was 32 and 28% for immobilization in PVA/PEG gels and in hollow beads, respectively, in synthetic juice (pH 3) after 72h at 25°C. Finally, the microbial cells entrapped in the cryogels showed a higher operational stability in orange juice than the encapsulated cells, with four consecutive cycles of reuse (runs of 24h at 25°C). KEY POINTS: • Increased tolerance to limonoids by adapting R. fascians with citrus by-products. • Entrapment provided cells with favorable microenvironment for debittering at acid pH. • Cryogel-immobilized cells showed the highest limonin degradation in citrus products.

Analysis of the Performance of Recycled Insulation Concrete and Optimal Mix Ratio Design Based on Orthogonal Testing.

Construction and agricultural waste recycling have gained more and more attention recently as renewable resources. Straw and construction waste, both of which are widespread in northern Fujian, were investigated in this research. The orthogonal test was used to investigate the effects of recycled aggregate, straw, and glazed hollow beads on the mechanical and thermal properties of recycled insulation concrete. The influence of different factors on the macroscopic characteristics of recycled insulation concrete was examined using scanning electron microscopy (SEM). The optimal mix proportion for recycled insulation concrete that satisfies mechanical performance standards and provides superior insulation performance was then determined using the total efficacy coefficient method. According to the research findings, the heat conductivity of recycled insulation concrete decreases as its dried density decreases. A 100% recycled coarse aggregate replacement rate, 1% straw content, and 10% glazed hollow beads replacement rate are the optimal mix ratios for recycled insulation concrete. With a compressive strength of 20.98 MPa, a splitting tensile strength of 2.01 MPa, a thermal conductivity of 0.3776 W/(m·K), and a dry density of 1778.66 kg/m3, recycled insulation concrete has the optimal mix ratio. Recycled insulation concrete is a novel form of eco-friendly, energy-saving concrete that aims to achieve low-carbon energy savings and sustainable development by combining resource recycling with building energy savings to realize the recycling of solid waste resources, which has significant environmental, social, and economic benefits and broad market application potential.

Ultra-Low-Density Drilling Fluids for Low-Pressure Coefficient Formations: Synergistic Effects of Surfactants and Hollow Glass Microspheres

With the increase in drilling fluid density requirements in low-pressure coefficient formations, traditional hollow bead drilling fluids and foam drilling fluids each have different degrees of deficiencies. Through extensive indoor experiments, an amphoteric surfactant (cocoamidopropyl betaine) with better foaming performance was selected to formulate an ultra-low-density drilling fluid that combines a foaming agent and hollow glass microbeads to reduce the density of the fluid, with the following specific formulation: 3% bentonite slurry + 0.3% xanthan gum + 0.5% carboxymethyl cellulose + 0.5% starch + 2% lignite resin + 2% blocking agent + 4% hollow glass microspheres + 0.5% foaming agent + 2% nano blocking agent. The performance of the system was evaluated, and the results showed that: the density of the ultra-low-density drilling fluid did not change much before and after aging at 80 °C and was relatively stable; the filter loss amount of the drilling fluid (tested by API) reached 4.6 mL, which meets the requirements for filter loss of drilling fluid; it can bear the pressure of 12 MPa under a 60–90-mesh sand bed and has better pressure sealing capability than hollow glass microbead drilling fluid.

Amine-functionalized cellulose nanofiber-sodium alginate-Fe(III) porous hollow beads for the efficient removal of Cr(VI)

Amine-functionalized cellulose nanofiber-sodium alginate-Fe(III) porous hollow beads for the efficient removal of Cr(VI)

Relationship between chloride ion permeation resistance of recycled aggregate thermal insulation concrete and pore structure parameters

The incorporation of recycled coarse aggregate (RCA) and glazed hollow bead (GHB) leads to a different internal pore structure of recycled aggregate thermal insulating concrete (RATIC) than that of normal concrete (NC), which is the fundamental reason for the different chloride ion transport mechanisms between the two. To investigate the quantitative relationship between the fine pore structure of RATIC and its resistance to chloride ion permeation in this study, chloride ion permeation tests were conducted on 10 sets of RATIC specimens with different RCA replacement ratios and GHB contents. The pore structure of the specimens, including their quantity and porosity, was also systematically analyzed using nuclear magnetic resonance (NMR) spectroscopy. A model for chloride ion permeation resistance of RATIC that considered RCA replacement and GHB content was proposed, and grey correlation analysis was used to relate the chloride ion permeation resistance of RATIC to the pore structure and establish a suitable chloride ion diffusion coefficient model for RATIC. The results showed that: (1) increasing RCA replacement weakened the resistance of RATIC to chloride ion permeation. Compared to normal concrete (NC), the chloride diffusion coefficient of RATIC increased by 18.73 % when the RCA substitution ratio rose from 0 % to 100 %, while the overall number of internal pores increased by 14.32 %, with the greatest increase in harmful pores under the same RCA replacement conditions; (2) increasing the GHB content effectively improved the chloride ion permeation resistance of RATIC, and the chloride ion diffusion coefficient decreased by 11.49 % when the GHB ratio rose from 0 kg/m3 to 130 kg/m3. The number of RATIC internal pores increased by a total of 20.29 %, with the largest increase in multiple harmful pores. The present authors concluded that establishing the two-parameter model of chloride ion diffusion coefficient/pore structure of RATIC could serve to predict the resistance of RATIC to chloride ion permeation, which could in turn provide a reasonable basis for further research on the durability of RATIC.