Table of Content

Volume 43 Issue 12
15 December 2024

Previous Issue 　

Cement and Concrete

A Review of Chemical Attack Resistance of Supersulfated Cement-Based Materials

CHANG Shuo, WANG Lu, LI Xinyu, LI Maosen, LIU Shuhua

2024, 43(12):  4271-4284. 

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Supersulfated cement (SSC) is a kind of green and low-carbon cementitious material, which has the advantages of low energy consumption, less heat release from hydration and high resistance to chemical attack. This paper mainly introduces the composition, early hydration properties, mechanical properties and chemical attack resistance of SSC. By comparing with Portland cement-based materials, it focuses on the chemical attack deterioration characteristics of SSC, including leaching, general acid attack and sulfate attack. On this basis, the chemical attack deterioration mechanism of SSC is further summarized. It provides theoretical guidance for the engineering application of SSC in different environments.

Research Progress on Synthesis of Polyacrylamide and Its Modified Cement-Based Materials

LIU Songhui, ZHANG Yizheng, AN Jiayi, GUAN Xuemao

2024, 43(12):  4285-4294. 

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Cement-based materials, as important building materials in construction and engineering, face a number of challenges during long-term application, such as easy cracking and easy penetration by solution. In order to solve the problems of high brittleness and susceptibility to cracking of traditional cement-based materials, polyacrylamide (PAM) modification technology has become a solution of great interest. The research progress of PAM modified cement-based materials was summarized systematically, including the structure and properties of PAM, synthetic monomers and methods, and applications in cement-based materials. The effect of PAM on cement-based materials, including mechanical properties, durability, permeability, and modulation of microstructure was discussed, and the mechanism of PAM modification was summarized. The importance and potential value of PAM-modified cement-based materials were emphasized. However, there are still some challenges to be overcome to further enhance the research and exploration. For this reason the future research direction should be devoted to optimizing PAM modification technology and expanding application areas, etc. In summary, PAM-modified cement-based materials have important research value and application prospects, which deserve further in-depth exploration.

Review on Preparation and Mechanical Properties of Ultra-High Performance Concrete

CHENG Xinlei, MU Rui, LIU Xiaoying

2024, 43(12):  4295-4312. 

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Ultra-high performance concrete (UHPC), as an advanced cement-based composite material, is widely used in special environments such as high cold, high saline, and ocean, or in building structures with large span and special strength requirements because of its excellent mechanical properties. Aiming at the methods for mechanical properties and improvements of UHPC, this paper starts with analyzing and introducing the latest research achievements in the mechanical property and improvements of UHPC in detail from the perspectives of design theory and preparation method, mechanical properties mechanism and characterization, influencing factors and control methods, and subsequently combines, analyzes and summarizes the material mixture design, curing regime, service environment of UHPC. It concludes with looking forward to the preparation method, durability research and related technical specification system of UHPC, which aims to promote the research, application and popularization of UHPC in engineering practice.

Effect of Ultramarine Blue Pigments on Hydration and Coloring Effect of White Portland Cement

LIU Jia, LIAO Yishun, XU Kaiqin, WAN Shihui

2024, 43(12):  4313-4321. 

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The aim of this study was to investigate the effects of ultramarine blue pigments on the physical and mechanical properties, hydration characteristics and coloring effect of white Portland cement. The white Portland cement was replaced by 2%, 4% and 6% ultramarine blue pigments, and the fluidity, setting time and compressive strength of the composite cementitous system were tested on the basis of the water-binder ratio of 0.45. The hydration rate and products were studied by electrical resistivity and thermal analysis method (TG/DTG) combined with XRD. The coloring effect of ultramarine blue pigments was studied in CIELAB color space. The results show that the fluidity and setting time of the white Portland cement paste decrease with the increase of ultramarine blue pigments content. The addition of ultramarine blue pigments increases the resistivity in 3 d of the white Portland cement paste and accelerates the cement hydration rate. Ultramarine blue pigments consume calcium hydroxide produced by cement hydration to form products similar to cement hydration, which makes the structure more compact and improves the compressive strength of cement samples. The higher the amount of ultramarine blue pigments, the darker the surface brightness of the samples becomes, and the color saturation point is basically reached when the content of pigments is 6%.

Resistance of Portland-Dolomite Micro-Powder Cement Mortar to Thaumasite Sulfate Attack

XU Jiangtao, LIU Fei, YANG Tong, LU Duyou

2024, 43(12):  4322-4329. 

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In order to evaluate the resistance of Portland-dolomite micro-powder cement mortar to thaumasite sulfate attack (TSA), the appearance, expansion and mass change of cement mortar in 5% (mass fraction) Na₂SO₄ solution at 5 ℃ were studied when the content of dolomite micro-powder was 0%~30% (mass fraction). The erosion products were analyzed by XRD, FTIR, TGA-DTG, SEM and thermodynamic simulation. The results show that the introduction of dolomite micro-powder significantly reduces the TSA resistance of cement mortar. With the increase of dolomite micro-powder content, the appearance damage grade, expansion degree and mass of mortar increase significantly. The higher the content is, the more significant the deterioration effect is. Compared with the reference sample, the cement mortar system containing dolomite micro-powder system produces more ettringite and gypsum in the early stage of erosion, and a large amount of thaumasite is generated in the later stage of erosion. Dolomite micro-powder participates in the hydration reaction of cement to form hydrotalcite, carboaluminate and calcite. In low temperature sulfate attack, the stable existence of hydrotalcite inhibits the formation of ettringite, while carboaluminate and calcite significantly promote the formation of thaumasite. The positive effect of the reaction of dolomite micro-powder to hydrotalcite is far less than the negative effect caused by the formation of carboaluminate and calcite, which eventually leads to TSA damage of cement mortar.

Effect of Aluminum Sulfate Based Alkali-Free Liquid Accelerator Modified by Aluminum Formate on Cement Properties

LIU Yuan, ZHU Fangfang, ZHANG Yuanyong, YANG Anxu, YANG Lin

2024, 43(12):  4330-4338. 

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Aluminum formate was used to modify aluminum sulfate based alkali-free liquid accelerator, and the performance index of alkali-free liquid accelerator modified by aluminum formate was tested in this paper. XRD, SEM, TG-DTG and hydration thermal analysis were used to analyze the effect of aluminum sulfate based alkali-free liquid accelerator modified by aluminum formate on the hydration process of cement. The results show that with the increase of aluminum formate content in aluminium sulfate based alkali-free liquid accelerator, the quick setting effect and strength of cement show a trend of increasing first and then decreasing. When the modified content of aluminum formate is 1% (based on the mass percentage of aluminum sulfate), the properties of cement with 8% modified aluminum sulfate based alkali-free liquid accelerator are as follows: initial setting time of 2 min 39 s, final setting time of 5 min 33 s, 1 d compressive strength of 13.2 MPa, 28 d compressive strength of 49.6 MPa, 28 d compressive strength ratio of 114%, and 90 d compressive strength retention rate of 123%, which meets the technical index requirements of the standard “Flash setting admixtures for shotcrete” (GB/T 35159—2017). When the modified content of aluminum formate exceeds 1%, a large amount of AFt inhibits the hydration reaction of C₃S in cement, resulting in the early and late strength reduction.

Early Compressive Strength Prediction and Extreme Value Optimization for High Performance Concrete

FAN Minghui, YANG Puxin, LI Wei, REN Wenyuan, MA Chicheng

2024, 43(12):  4339-4349. 

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7 d compressive strength of high performance concrete, as an important indicator of early strength, has a significant impact on the quality of construction projects that cannot be ignored. In order to achieve high performance concrete compressive strength prediction and extreme value optimization, this paper optimised the BP neural network based on the logistic chaos mapping improved sparrow search algorithm (LCSSA), and established the LCSSA-BP prediction model. 88 sets of data were selected as the training set and 38 sets of data as the test set to compare the prediction results of BP,support vector machine (SVM), extreme learning machine (ELM), artificial bee colony algorithm-BP (ABC-BP) and cuckoo search-BP (CS-BP) models. The prediction accuracy of the LCSSA-BP model was verified from the perspectives of data set division and the number of input variables. Genetic algorithm was used for compressive strength optimization to determine the optimum mix proportion for high performance concrete. The study shows that compared with other models, the LCSSA-BP model has higher prediction accuracy and lower prediction error; when the training set and test set are divided according to 9-1, the determination coefficient R² of model is 0.975 and correlation coefficient R is 0.987; considering the correlation degree of the variables and the characteristics of the data distribution, when cement, blast furnace slag, water, coarse aggregate and fine aggregate are selected as input variables, the R² is 0.954, R is 0.977; the genetic algorithm has high feasibility and practicability in the optimization of high-performance concrete early 7 d compressive strength and mix proportion design.

Experimental Study on Early Temperature and Strain of Steam Curing Prestressed Concrete Box Girders

JIN Qingping, LIANG Yingqiang, GAO Yonghong, WANG Xihua, XU Pinghua, SONG Guoying

2024, 43(12):  4350-4358. 

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In order to study the influence of steam curing on high volume concrete box girder, combined with high temperature steam curing precast concrete box girder project of a Yangtze River Bridge, the temperature and strain sensors were embedded in the 30 m box girder, and the temperature and strain changes of box girder during steam curing and later curing were obtained. The results show that the average temperature of test section is lower than mold temperature after 66 h. The hydration heat of concrete reaches the peak value at 11~13 h, and the peak temperature of measuring points in each area of the section from large to small is the junction of top web plate, the top plate, the web plate, the bottom plate and the junction of bottom web plate. The peak temperature at the junction of top web plate and top plate is higher than that in other areas. The maximum temperature difference between interior and surface, and between surface and exterior of box girder is 18.62 and 14.29 ℃, respectively, both of which appear before steam curing. During the whole curing process, the tensile stress generated inside the box girder is less than splitting tensile strength of concrete, and there is no risk of cracking in girder. After the tension of prestressed steel beam is completed, the strain of each test section is compressive strain, and the later change range is not large.

Influence of Layer Treatment on Crack Propagation in Roller Compacted Concrete Shear Process

LI Yang, ZHUANG Xiaolong, LI Zhilong, WANG Jing, CHAI Jiaqi

2024, 43(12):  4359-4369. 

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In order to study the law of crack propagation inroller compacted concrete layer shear process, this paper carried out shear strength tests on roller compacted concrete treated at different layers, and analyzed the failure modes and shear strength change law of different specimens. At the same time, digital image correlation technology was used to observe the development law of layer cracks in roller compacted concrete shear process, and the influence of hydration degree of layers on crack propagation was analyzed by thermogravimetric technology. The results show that the layer treatment can effectively improve the bonding effect and shear strength of layer, and reduce the crack width and propagation rate. The roller compacted concrete layer treated with nano-SiO₂ mortar has the best bonding effect, and the maximum crack width and propagation rate are reduced to 0.528 mm and 1.412 mm/s, respectively. The development process of layer cracks is divided into four stages: initial, initiation, expansion and connection. Nano-SiO₂ can promote the hydration of cement, and the content of hydration products is negatively correlated with maximum crack propagation rate. Therefore, the addition of nano-SiO₂ can effectively reduce layer crack propagation rate.

Effects of Silicon Carbide Materials on Mechanical Properties and High Temperature Properties of Concrete

YANG Shuting, ZHOU Niuniu

2024, 43(12):  4370-4377. 

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Nano-silicon carbide, silicon carbide whisker and silicon carbide fiber were added into concrete. The effects of three kinds of silicon carbide materials with single addition on the mechanical properties of concrete were studied, and the optimal content of three kinds of silicon carbide materials was determined. The improvement effects of three kinds of silicon carbide materials on the mechanical properties of concrete were compared and analyzed. On this basis, the high temperature test of concrete was carried out, and the effects of three kinds of silicon carbide materials on the high temperature properties of concrete were studied. The effect mechanisms of three kinds of silicon carbide materials on the properties of concrete were analyzed by SEM test. The results show that nano-silicon carbide, silicon carbide whisker and silicon carbide fiber can improve the mechanical properties and high temperature properties of concrete. When the content of nano-silicon carbide, silicon carbide whisker and silicon carbide fiber is 2.0%(mass fraction), 3.0%(mass fraction) and 0.3%(volume fraction), the mechanical properties of concrete are the best. The improvement effect of nano-silicon carbide on compressive strength and residual compressive strength after high temperature of concrete is the best, and the improvement effect of silicon carbide whisker on flexural strength, splitting tensile strength and residual flexural strength after high temperature of concrete is the best. In concrete, nano-silicon carbide plays the role of filling and nano-nucleation, silicon carbide whisker plays the role of filling and cracking resistance, and silicon carbide fiber plays the role of cracking resistance. Silicon carbide materials have good high temperature properties, it remains intact at high temperature and can still play a role.

Effect of Micro-Nano Bubble Water on Performance of Shotcrete

CHENG Lihua, DU Hang, YANG Yonghao, YAN Guoguang, ZHOU Kun, TANG Shuang, FU Tianbao

2024, 43(12):  4378-4388. 

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Micro-nano bubble water (MNBW) has the characteristics of large specific surface area, good stability and high activity of water molecules. MNBW can be used to mix shotcrete to improve the physical and mechanical properties of shotcrete. MNBW was selected as the mixing water, and the effects of MNBW bubble gas type, MNBW shear time, MNBW content and alkali-free liquid accelerator content on the setting time of cement paste and the mechanical properties of cement mortar were studied. The digital image acquisition technology was used to explore the interface crack propagation law of cement mortar during uniaxial compression. The results show that MNBW (especially MNBW containing CO₂ bubbles) can significantly promote the hydration reaction of cement and shorten the setting time of cement paste. The compressive strength and flexural strength of cement mortar increase with the increase of MNBW content and curing age, and increase first and then decrease with the increase of MNBW shear time. In the process of uniaxial compression failure, the load value required for the initial crack initiation of different mixed water specimens from large to small is CO₂ bubble MNBW group, air bubble MNBW group, and tap water group.

Durability of Concrete Structures in Salt and Freshwater Confluence Area

LI Yi, TANG Bowen, LI Wei, DING Pingxiang, FAN Zhihong

2024, 43(12):  4389-4397. 

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The alteration of corrosion mediums in the salt and freshwater confluence area is poorly understood, with low concentrations complicating matters further. This significantly changes the corrosion patterns of concrete structures, rendering the chloride diffusion models developed for marine environments inaccurate for predicting the lifespan of concrete structures in such salt and freshwater confluence areas. Additionally, the deterioration mechanisms in the salt and freshwater confluence area differ from those in marine environments. Hence, applying marine protective measures to these areas would lead to substantial resource wastage. To address this issue, this study leveraged the Nansha Bridge project, employing field tests, laboratory tests, and theoretical analyses to investigate the durability of concrete structures in the salt and freshwater confluence area. First, the carbonation and chloride corrosion of the concrete structure under different corrosion environments at Nansha Bridge were analyzed. Subsequently, the pore distribution, chemical composition, and microstructure of the concrete were characterized by mercury intrusion porosimetry (MIP), thermogravimetric (TG) analysis, and scanning electron microscopy (SEM). This study may have potential for the life prediction, repair, and reinforcement of concrete structures in the salt and freshwater confluence area.

Performance of Vegetation-Type Concrete Based on Orthogonal Experimental Method

LIU Ping, XU Yanping, LIU Fei, PAN Jian, FAN Zhihong

2024, 43(12):  4398-4405. 

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Vegetation-type concrete is a new type of slope protection material that can effectively combine engineering protection and ecological restoration, achieving long-term sustainable ecological slope protection.Based on the orthogonal experimental method, the mix proportion design of slope vegetation-type concrete was carried out using low alkalinity sulfoaluminate cement, and the effects of concrete water cement ratio, aggregate particle size, and surplus cement pastes content on compressive strength, porosity, and pH value were compared. Obtain the optimal mix proportion and conduct vegetation-type concrete laying and plant planting experiments on the slope of the Pinglu Canal based on this foundation. The results show that when the water cement ratio is 0.28, the aggregate particle size is 9.5~19 mm, and the surplus cement pastes content is 7.75, the vegetation-type concrete achieves the best vegetation performance. Choose dogtail grass, bermuda grass, and broadleaf grass for optimal results when planted alone or in combination.

Solid Waste and Eco-Materials

Optimization of Natural Desert Sand Concrete Mix Ratio

LIU Yubin, HUANG Yong, YU Rui, SUN Jian, GUO Lulong, LIANG Xinming, ZUO Baoxi

2024, 43(12):  4406-4416. 

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In order to make full use of natural resources in Xinjiang and achieve the purpose of “local materials” and “disaster prevention”, this paper uses natural desert sand to replace concrete aggregate and adds fly ash and silica fume to cementitious materials to optimize the mix ratio of concrete. Firstly, the effects of four factors, such as fly ash content, water-binder ratio, cement-sand ratio and water reducer content, on the performance of desert sand concrete were studied by orthogonal test. The range, factor index and variance analysis were carried out in combination with the compressive and splitting tensile strength of natural desert sand concrete. Subsequently, the effect of silica fume content on the mechanical properties and working performance of natural desert sand concrete was investigated by single factor test. The results show that the optimal mix ratio of natural desert sand concrete is fly ash content of 20% (mass fraction, same below), water-cement ratio of 0.33, cement-sand ratio of 1 ∶2, and water reducer content of 0.8%. The addition of silica fume can significantly improve the compressive strength of desert sand concrete, but it will reduce the working performance of desert sand concrete. When 10% silica fume is added, the mechanical properties and working performance of desert sand concrete are the best.

Influence of Desert Sand on Creep of Concrete

QIU Chengjiang, ZHAO Yong, HE Zhihai

2024, 43(12):  4417-4423. 

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In order to further promote the application of desert sand concrete, the influence of desert sand replacing river sand with different content (25%, 50% and 75%, mass fraction) on the creep of concrete was studied by prestressed loading method, and the influence mechanism was analyzed in the combination with pore structure and microscopic morphology. The results show that the desert sand replacing 25% river sand increases the compressive strength and elastic modulus of concrete, which increase by 7.5% and 3.6% at 28 d, respectively, and reduces creep of concrete. The creep strain of concrete at 180 d is reduced by 31.7%, the specific creep at 180 d is reduced by 35.7% and the creep coefficient at 180 d is reduced by 32.1%. With the further increase of the replacement rate of desert sand, the compressive strength and elastic modulus of concrete are reduced, and the creep of concrete is improved. The desert sand replacing river sand increases the porosity with pore diameter less than 50 nm which is associated with the creep. The desert sand replacing 25% river sand reduces the porosity with pore diameter greater than 50 nm of concrete which is associated with the strength, and the internal structure of concrete is improved. With the further increase of the replacement rate of desert sand, the internal structure of concrete is loosened.

Mechanical Properties and Microscopic Mechanism of Mixed Mortar with Gangue Machine-Made Sand and Eolian Sand

QIU Jisheng, NIU Gaohui, LI Leilei, FENG Zeping, LI Le

2024, 43(12):  4424-4433. 

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Mixed mortar is a new type of mortar that is prepared by using gangue machine-made sand and eolian sand to replace river sand in different proportion (equal mass). To explore the change rule and microscopic mechanism of the basic mechanical properties of mixed mortar, the mixed mortar specimens were prepared with the eolian sand of Mu Us Desert and the gangue machine-made sand of the Daliuta Coal Mine. The compressive strength change rules of mixed mortar with the two kinds of sand mixed ratio, curing age, and mixed sand fineness modulus were studied, and the internal mechanism of the strength change rule was revealed. The results show that with the increase of the proportion of eolian sand, the strength of mixed mortar increases first and then decreases, and the optimal mixing ratio of gangue machine-made sand and eolian sand is 6 ∶4 (mass ratio). The compressive strength of mixed mortar and the fineness modulus of mixed sand satisfy the quadratic function relationship. When the fineness modulus of mixed sand is 2.20, the mechanical properties of mortar are the best. The particles of different particle sizes of mixed sand fill each other, which reduces the internal pores of the mortar. The addition of an appropriate amount of eolian sand can disperse the large bubbles retained in the mortar into tiny bubbles and improve the structure of the mortar. The concepts of beneficial pore and harmful pore are proposed. Based on the pore structure parameters, the change process of mechanical strength of mortar is explained, which shows that the compressive strength of mortar is the result of the combined action of its internal porosity and pore size distribution range. The appropriate amount of aeolian sand mixed with gangue machine-made sand is conducive to the hydration reaction, which has a “compensation effect” on the structure. However, with the further increase of aeolian sand content, due to the defects of aeolian sand itself, this “compensation effect” cannot make up for the defects of the material itself.

Effects of Combustible Components of Coal Gangue on Properties of Lead-Zinc Tailing Ceramsite

WAN Xindi, ZHANG Maoliang, SU Genhua, LUO Zhongtao, LIU Xiaohai

2024, 43(12):  4434-4441. 

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In this paper, the effects of carbon and sulfur combustible components from coal gangue on the physical properties and heavy metal solidification properties of ceramsite were studied. The phase composition and microstructure changes of ceramsite were analyzed by XRD and SEM. The results show that the carbon and sulfur combustible components in coal gangue increase the apparent density and compressive strength of ceramsite, significantly reduce the water absorption and weaken the heavy metal solidification ability of ceramsite. The prepared ceramsite meets the environmental safety requirements. The addition of carbon and sulfur components could promote the transformation of mullite and quartz into anorthite and reduce the content of open pores due to the effects of forming pores by combustion at low temperature and increasing liquid phase at high temperature.

Effect of Pre-Wetting Heavy Metal Sludge Sintered Pottery Sand on Performance of Ultra-High Strength Concrete

WANG Sheng, MA Hongrui, JI Luxin, MA Zheyang, CUI Jiaming, BA Mingfang, SHAO Nianping

2024, 43(12):  4442-4451. 

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In order to solve the problem of volume stability failure of ultra-high strength concrete and realize high value utilization of heavy metal sludge, this paper proposed to use heavy metal sludge sintered pottery sand to replace part of river sand to prepare ultra-high strength concrete. The effects of different content and particle grade of pottery sand on the working performance, mechanical properties and shrinkage properties of ultra-high strength concrete were studied. The effect of pottery sand on the phase composition, microstructure and pore structure of ultra-high strength concrete were studied by XRD, TG-DTG, FTIR and SEM microscopic test methods. The results show that the pre-wetting heavy metal sludge sintered pottery sand has significant internal curing effect on the early stage of ultra-high strength concrete.When the curing age is 14 d, compared with the reference group, the autogenous shrinkage of ultra-high strength concrete with medium sand is reduced by 11.0%~27.6% ,and the flexural strength is increased by 13.5% when the content of pottery sand is 20% (mass fraction). The incorporation of pottery sand can accelerate the early hydration reaction of ultra-high strength concrete, generate more hydration products, and increase the compactness of structure. However, the pre-wetting heavy metal sludge sintered pottery sand will adversely affect the strength of ultra-high strength concrete, and its content and particle grade should be controlled.

Effects of Rubber Form and Substitution Ratio on Basic Properties of Manufactured Sand Mortar

YAN Yongdong, TAN Lei, LU Chunhua, YUAN Siqi, WANG Xin

2024, 43(12):  4452-4460. 

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In order to reduce the adverse effects of waste rubber landfill on the environment, in this paper, crushed rubber as fine aggregate was mixed into mortar and experiments were conducted on the effects of different substitution ratios of rubber particles (NR20) and rubber fibers (NRS) on the workability, mechanical properties, and impact resistance of manufactured sand mortar. The results show that as the rubber substitution ratio increases, the consistency of rubber particle mortar gradually increases, and the delamination degree gradually decreases, while the consistency of rubber fiber mortar decreases first and then remains basically unchanged, and the delamination degree gradually increases. In addition, the compressive and flexural strength of rubber mortar decrease with the increase of rubber substitution ratio, and the compressive and flexural strength of rubber fiber mortar is higher than that of rubber particle mortar. Rubber changes the impact failure mode of mortar from single crack to multiple crack. The more rubber is added to the mortar, the higher the impact energy consumption for impact failure required is, and the impact energy consumption of rubber fiber mortar is higher than that of rubber particle mortar.

Mechanism of Preparing Calcium Sulfate Dihydrate Whiskers from Phosphogypsum under Atmospheric

WU Kaizhen, LI Rui, LI Yubiao, WU Xiaoyong, SUN Xuchao, XUE Lutao, CHEN Xin, CHI Ru’an

2024, 43(12):  4461-4470. 

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Phosphogypsum(PG) is a bulk solid waste produced during wet phosphoric acid process, which is largely stocked and can cause seriously environmental pollution. Therefore, it is urgent to remove impurities, realizing its high valuable utilization as a resource. In this study, PG was extracted and purified bythermolysis purification using hydrochloric acid to obtain high quality and high lengh-diameter ratio calcium sulfate dihydrate whisker. Besides, the growth mechanism of calcium sulfate dihydrate whisker was simulated based on molecular dynamics. The results show that at 80 ℃, reaction time of 1.5 h and 4 mol/L hydrochloric acid, the mass fraction of calcium sulfate dihydrate in PG increases from 82.50% to 99.80% after thermolysis purification. In addition, after thermolysis purification, the content of P₂O₅ decreases from 1.78% (mass fraction, the same below)to 0.03%, the mass fraction of SiO₂ decreases from 7.37% to 0.02%, and fluorine is almost completely removed. Finally, calcium sulfate dihydrate whisker products are obtained. The simulation calculation results exhibit that calcium sulfate dihydrate is more soluble in hydrochloric acid solution than that in pure water at 298 K. In addition, the solubility of calcium sulfate dihydrate decreases at increased temperature. Moreover, the (020) plane of calcium surfate dihydrate presents the lowest interplanar spacing, in which calcium sulfate ions are more closely arranged and conducive to the formation of orderly and complete crystals. The growth mechanisms of whisker indicate that, firstly, calcium sulfate dihydrate gradually dissolve into hydrochloric acid. At higher temperatures, the solution begins to supersaturate, calcium sulfate crystals precipitate to form crystal nuclei. Subsequently, the crystals grow along the spiral dislocation of (020) plane of calcium surface dihydrate, thereby forming calcium sulfate dihydrate whisker.

Performance and Curing Mechanism of Sodium Silicate Modified Phosphogypsum Road Stabilizing Material

HUANG Xuquan, CAI Jiawei, ZHAO Xiaorong, XUE Fei, WANG Haojie, WANG Jun, WANG Ming

2024, 43(12):  4471-4479. 

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With the purpose of resource utilization of phosphogypsum, this paper explored the optimal ratio design of silica fume and cement curing high-concentration original phosphogypsum to prepare road stabilizing materials, on this basis studied the performance of sodium silicate enhanced road stabilizing materials, and analysed the curing mechanism. The results show that when the mass ratio of cement, silica fume and slaked lime is 5 ∶3 ∶2, and 1.5% (mass fraction) of sodium silicate is added, the mechanical properties and water resistance of phosphogypsum road stabilizing materials are significantly improved, and the unconfined compressive strength of 28 d reaches 9.77 MPa, the softening coefficient reaches 0.81, and the water stability coefficient reaches 1.0. At the same time, the concentration of fluorine ions and soluble phosphorus in the leaching solution meets the first-level limit of the "Comprehensive sewage discharge standard" (GB 8978—1996). Microscopic tests show that a large amount of hydrated calcium silicate gel produced by the hydration reaction could wrap calcium sulfate dihydrate. At the same time, the filling effect of silica fume and sodium sulfate makes the overall structure more dense, forming a phosphogypsum road stabilizing material with good performance.

Influence of Modified Wheat Straw on Performance of Cement Stabilized Crushed Stone

QIN Jiaming, WANG Huan, WANG Jianqi, JIA Liwang

2024, 43(12):  4480-4490. 

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In order to study the effect of modified wheat straw on the performance of cement stabilized crushed stone, the surface modification of wheat straw was carried out by using different concentrations of NaOH solution, and the effects of NaOH solution concentration and modification time on the quality of straw were analysed. The modified straw fibers were incorporated into cement stabilized aggregates, and the optimal fiber ratios were obtained through the unconfined compressive strength test and splitting strength test. The dry shrinkage test and freeze-thaw test were carried out under the optimal fiber ratios, combined with the environmental scanning electron microscope (ESEM) test, to observe the microscopic changes of wheat straw before and after modification, as well as the role of straw fibers in the cement stabilized aggregates. The results show that: the mass loss rate of wheat straw is higher when wheat straw is modified by 3.5% (mass fraction) NaOH solution for 12 h, which is conducive to reducing the retardation effect on cement; the mechanical properties of straw fiber in cement stabilized crushed stone are significantly enhanced, and the strength is the highest when the fiber length is 20 mm and the dosage is 0.15% (mass fraction), and withthe prolongation of the curing age, the mechanical properties of cement stabilized drushed stone are continuously improved. Compared with ordinary cement stabilized crushed stone, the dry shrinkage performance and frost resistance of straw fiber cement stabilized crushed stone are significantly improved. ESEM analysis shows that the modified wheat straw can improve the adhesion with the matrix, prevent or delay the generation and development of cracks, and improve the mechanical properties and anti-cracking properties of cement stabilized crushed stone.

Preparation of Shield Grouting Material with Recycled Fine Powder from Waste Concrete and Its Performance Evolution

ZHENG Shengbiao, CHU Yuting, GAO Peng, ZHAN Binggen, WANG Guotao, ZHANG Qingfeng, LU Bingdou

2024, 43(12):  4491-4500. 

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Recycled fine powder (RFP) produced by the disintegration of waste concrete has high yield and certain activity, which is expected to partially replace cement, fly ash and bentonite to prepare RFP shield grouting material. However, RFP influence on the performance of shield grouting material is not clear, which is difficult to guide engineering application. In this paper, the initial fluidity, setting time, compressive strength and drying shrinkage of RFP shield grouting material were tested. The results show that the RFP replacement of cement is easy to decrease the rheological properties of shield grouting material. When RFP replaces 12.5% (mass fraction, same below) cement, the fluidity of shield grouting material is 17.6 cm, which does not meet the specification requirements (21±3) cm. The replacement of bentonite by RFP results in the deterioration of slurry mance. When RFP replaces 30% bentonite, the shield grouting material bleeding rate is 5.2%, and the stratification phenomenon occurs. The replacement of fly ash by RFP is beneficial to improve the fluidity. When RFP replaces 30% fly ash, the fluidity of shield grouting material increases by 16.5%, the bleeding rate is low, and there is no stratification. The RFP ‘micro-aggregate’ effect builds a rigid support skeleton, which can reduce the porosity of shield grouting material and effectively inhibit drying shrinkage. Based on the performance of all aspects, the optimum slurry ratio is: water-binder ratio 0.31, cement-sand ratio 0.66, cement 27%, bentonite 44.5%, fly ash 9.4%, RFP 19.1%, water reducer 0.3%.

Preparation of P-Type Molecular Sieves from Fischer-Tropsch Synthesis Waste Slag and Its Applications

LI Qiaoqiao, LIU Hongying, ZHANG Qiuwen, WANG Lvyin, TAN Qixiang

2024, 43(12):  4501-4511. 

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In order to realize the efficient resource utilization of industrial Fischer-Tropsch synthesis process, P-type molecular sieves were prepared from Fischer-Tropsch synthesis residue with a lot of silicon and aluminum after dewaxing by alkali-fusion-hydrothermal method. The effects of Si/Al ratio, alkali/Si ratio, crystallization temperature and crystallization time on the preparation of P-type molecular sieves were systematically investigated. XRD, FT-IR, SEM and other characterization means were used to analyze the crystalline shape, morphology and structure of the molecular sieves, and the adsorption properties of P-type molecular sieves with Pb²⁺ were investigated. The results show that the P-type molecular sieves synthesized from waste slag under the conditions of n(SiO₂)/n(Al₂O₃)=6.5, n(Na₂O)/n(SiO₂)=1.8, T=90 ℃, and t=24 h have a clear and regular morphology profile, no impurity crystalline phases, the highest degree of crystallinity, which is 86.39%, and the largest specific surface area, which is 99.8 m²/g. The maximum equilibrium adsorption capacity of Pb²⁺ in the Fischer-Tropsch synthesis waste slag-based P-type molecular sieves reaches 322.85 mg. The adsorption process is analyzed for adsorption kinetics and it is found that the process conformed to a quasi-secondary kinetic model with an adsorption equilibrium of 319.47 mg/g.

Preparation and Properties of Composite Acid Gas Adsorbents

QIU Xiumei, LIU Yedongyang, CAI Hao, GONG Guan, LIANG Yaqi

2024, 43(12):  4512-4520. 

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The study aimed at the efficient disposal of acidic harmful gases generated in the production of laboratories and analysis rooms in mining, geology, metallurgy and other industries. Natural clay minerals, alkali metal minerals and inorganic additives were took as raw materials, a series of composite acid gas adsorbents were prepared through formula design and extrusion molding, and their adsorption performances were studied by acid solution immersion experiment and fixed bed dynamic adsorption experiment. The results show that the soaking adsorption amounts of composite acid gas adsorbent on HCl and HNO₃ are 0.50~0.80 g/g and 0.55~0.95 g/g, and the adsorption amounts of Cl^- and NO^-₃ on volatile HCl and HNO₃ absorbed for 4 h are more than 35 and 40 mg/g, respectively, which are much higher than that of activated carbon and the same type of products on the market. The composite acid gas adsorbent has uniform microporosity, and its microstructure and chemical composition are more conducive to the diffusion, capture and reaction of volatile acid gas. The adsorption process on Cl^- and NO^-₃ is in accordance with the pseudo-second order kinetic model, which indicates it is mainly through chemical adsorption and absorption, and physical adsorption to remove volatile HCl, HNO₃ acid gas. The composite acid gas adsorbent has certain promotional value.

Ceramics

Progress on Cordierite Based Ceramic Materials Prepared from Industrial Wastes

LAI Yuefei, WANG Huijun, ZENG Qiang, XIONG Chengrong, SU Xiaoli, LUO Ting

2024, 43(12):  4521-4531. 

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Cordierite has the advantages of low thermal expansion coefficient, good thermal shock resistance and high refractoriness, and is widely used in metal smelting, glass, ceramics and other fields. The raw materials of industrial wastes are widely available and cheap. Using industrial wastes to prepare cordierite can not only reduce the cost of raw materials and alleviate the huge consumption of mineral raw materials, but also solve the problem of land occupation and environmental pollution caused by the accumulation of industrial wastes. In this paper, the researches status of high value-added cordierite glass-ceramics, porous ceramics and composite materials prepared from industrial wastes are reviewed.A systematic review is conducted on the research progress of preparing cordierite-based ceramic materials from industrial wastes and the influence mechanism of additives on the preparation of cordierite ceramic materials from industrial wastes. Furthermore, the problems existing in the application of high temperature industrial wastes to prepare cordierite material are summarized, and the directions and ideas for the effective resource comprehensive utilization of high temperature industrial wastes are provided.

Preparation of Iron Oxide Red from Titanium Industrial Solid Waste and Its Application in Ceramic Black Pigments

DUAN Ning, PENG Shaoxin, LU Chenglong, ZHANG Yinfeng, ZHANG Fan

2024, 43(12):  4532-4544. 

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The accumulation of iron-rich tailings, a solid waste from the titanium industry, poses significant environmental pollution risks. To address this and convert the tailings into valuable resources, this study employed an acid leaching-purification-oxidation-calcination process. This process utilized the iron content in the tailings to produce iron oxide red, which is then used as an iron source to synthesize iron-chromium spinel for application in black ceramics. This paper investigated the effects of initial Fe²⁺ concentration, reactant molar ratio, and oxidizing temperature on the formation of iron oxide yellow crystal seeds. Building on this, the study explored how different calcination temperatures influence the properties of iron oxide red, its conversion into iron-chromium spinel, and its impact on the coloration of black ceramics. The results show that under the conditions of 0.4 mol/L Fe²⁺ concentration, a reactant molar ratio of 2.2 ∶1, and an oxidation temperature of 35 ℃, the iron oxide yellow crystal seeds obtained from acid-leached purified ferrous chloride solution are calcined at 750 ℃. This produced red iron oxide has a purity of 98.875%, an average particle size of 2.973 μm, and a high degree of crystallinity in a rod-like shape. Using this red iron oxide as a precursor, the iron-chromium spinel formed by sintering at 1 280 ℃ exhibits the best blackening effect in black ceramic color plates, with a L^* value of 37.35, differing by only 0.57 from the standard sample.

Effect of MgTi₂O₅ on Low Temperature Synthesis and Properties of Aluminum Titanate Ceramics

ZHANG Hongquan, CHENG Guangjian, WEN Jin, CHEN Pengjie

2024, 43(12):  4545-4552. 

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In this paper, pre-synthesized MgTi₂O₅ and MgO+2TiO₂ in-situ synthesized MgTi₂O₅ were introduced as the additives required for the preparation of aluminum titanate ceramics, and the effect of MgTi₂O₅ on the phase composition and properties of aluminum titanate ceramics was studied. The results show that MgTi₂O₅ or MgO+2TiO₂ can promote the synthesis of aluminum titanate at low temperature by forming solid solution, the addition of a small amount of MgTi₂O₅ can effectively promote the synthesis of aluminum titanate crystals at a lower temperature. When the MgO content is 2% (mole fraction), the synthesis rate of aluminum titanate added with MgTi₂O₅ at 1 300 ℃ is 28.4 percentage point higher than that of MgO+2TiO₂. On the premise of similar synthesis rate of aluminum titanate, the firing temperature of adding MgTi₂O₅ is lower than that of adding MgO+2TiO₂. When 6%MgTi₂O₅ is added, the thermal expansion coefficient of the ceramic samples fired at 1 280~1 350 ℃ is between -0.11×10^-6 ℃^-1 and 0.58×10^-6 ℃^-1. With the increase of firing temperature, due to the anisotropy and overgrowth of crystal, the microcracks inside crystal are easy to reduce the flexural strength of obtained aluminum titanate ceramics.

Comparative Study on Effect of Rheological Properties on Stability of Ceramic Slurry

BAO Zhilei, YU Huan, JIANG Chao

2024, 43(12):  4553-4562. 

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In ceramic production, the stability of slurry plays a crucial role in ensuring high product quality and production efficiency. This study was conducted to investigate the effects of rheological properties on the suspension stability of ceramic slurry. The effects of various stabilizers, such as polyethylene glycol, polyoxyethylene oxide, polyvinyl alcohol, and guar gum, on the rheological properties of ceramic slurry were analyzed. Then, the independent effects of shear viscosity and elasticity on the stability were compared. The results show that there are significant differences in suspension stability of ceramic slurry with different stabilizers under the same particle size and volume fraction condition, although the viscosity is similar. Notably, the slurry that utilized guar gum as a stabilizer exhibits the best stability. Furthermore, the storage modulus G′, loss modulus G″, and loss factor tan δ are the key viscoelastic parameters that affect the stability of ceramic slurry. When the elasticity of ceramic slurry is same, the stability of slurry is improved with the increase of shear viscosity. The results emphasize the importance of elasticity and viscosity of slurry in suspended particles. The study highlights that viscoelastic parameters and viscosity have noticeable effects on particle settlement behavior, offering a fresh perspective for stability research and application of ceramic slurry. The research provides valuable references and suggestions for selecting appropriate stabilizers to enhance the stability of ceramic slurry and optimize the formulation and production process.

Synthesis of Spheroid Ba(Mg_1/3Ta_2/3)O₃ Nano-Powders by Hydrothermal Method

ZUO Chuandong, WAN Jingqi, WEI Boxu, YANG Zaiwen, ZUO Chuange, MA Chaoyang

2024, 43(12):  4563-4570. 

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Barium magnesium tantalate (Ba(Mg_1/3Ta_2/3)O₃, BMT) ceramics has excellent microwave dielectric properties. It’s the key point to synthesize BMT nano-powders with well-crystallized, uniform grain, good dispersion for perfect microwave dielectric ceramics. BMT nano-powders were prepared by hydrothermal method using tantalum oxide, magnesium nitrate, and barium nitrate as raw materials, KOH solution and isopropyl alcohol as solvents. The crystal structure, morphology, and particle size of the product were characterized by X-ray diffractometer and scanning electron microscope. The effects of KOH concentration, reaction temperature, and reaction time on BMT powders were investigated. The effect of calcination temperature on BMT powders was studied by differential thermal analysis. The results show that the optimum conditions for the synthesis of BMT nano-powders are KOH concentration 2 mol/L, reaction temperature 200 ℃, reaction time 24 h and calcination temperature 1 000 ℃ after freezing-drying. Under this condition, the obtained BMT nano-powders particles are spherically dispersed, and the particle diameter is about 100 nm. This method can be used as a reference for hydrothermal synthesis of BMT nano-powders.

Preparation and Properties of Low-Density and High Strength Ceramic Proppants

FENG Ming, JI Guorong, GAO Yunfeng, MU Weipeng, ZHU Baoshun, TIAN Yuming, BAI Pinbo

2024, 43(12):  4571-4577. 

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A low-density and high strength ceramic proppant was prepared using secondary bauxite (Al₂O₃ mass fraction 70.3%) and fly ash as raw materials, with different content of dolomite as additive, at a sintering temperature of 1 350 ℃. The solid waste fly ash was effectively utilized, and the influence of dolomite on the grain development and properties of ceramic proppants was investigated. The influence of dolomite content on the microstructure and physical properties of bauxite-fly ash based ceramic proppants was studied through characterization methods such as XRD, SEM, and physical performance testers. The results show that the addition of appropriate content of dolomite can significantly promote the growth and development of rod-shaped mullite, and reduce the crushing rate of ceramic proppants. In addition, the formation of closed pores within the matrix can reduce the bulk density and apparent density of ceramic proppants. When the addition content of dolomite is 6%(mass fraction), the prepared ceramic proppants has the best performance, with a bulk density of 1.45 g/cm³, an apparent density of 2.60 g/cm³, and a crushing rate of 6.5% at 35 MPa.

Glass

Effect of Chemical Reinforcement Process on Impact Resistance of 3~6 mm Thick Lithium Aluminosilicate Glass

GAO Qiang, LIU Zhenying, PENG Xiaobo, SHI Lifen, ZHOU Gang, ZHOU Jun, CHEN Shiwei

2024, 43(12):  4578-4587. 

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The new generation of lithium aluminosilicate glass has gradually become the mainstream structural material for aerospace transparencies. Due to its high elastic modulus and excellent ion exchange capability, lithium aluminosilicate glass exhibits superior mechanical properties after chemical reinforcement treatment, well meeting the requirements of lightweight and high strength for aerospace transparencies. This paper aims to explore the effect of chemical reinforcement processes on impact resistance of 3~6 mm thick lithium aluminosilicate glass. Samples were prepared under different reinforcement conditions, and the effect of stress distribution on impact resistance was analyzed through ball-drop impact testing and theoretical calculations. It is found that for thick lithium aluminosilicate glass, as the depth of the stress layer increases, the growth of central stress is slower. Moreover, thicker lithium aluminosilicate glass exhibits a slower growth rate of central stress, and its impact resistance improves with the increase in the depth of the stress layer, which differs from the pattern observed in thin lithium aluminosilicate glass.

Fast Evaluation Method for Post-Fracture Tensile Properties of Laminated Glass Based on Convolutional Neural Network

YIN Junxi, PENG Shennan, WANG Xinger, YANG Jian

2024, 43(12):  4588-4596. 

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The post-fracture load-bearing properties of laminated glass is crucial for the safety of architectural glass structures under long-duration wind disasters or explosions. Crack morphology significantly impacts the tension-stiffening effect and the triggering of local failure in laminated glass. Fragmentation tests and post-fracture uniaxial tensile tests were conducted on laminated tempered glass with SG interlayer to obtain the testing datasets of crack morphological images and associated mechanical properties. The refined finite element (FE) models were then calibrated with experimental outcomes to determine key parameters such as fragment density, minimum nearest neighbour distance, and effective bonding coefficients corresponding to the crack morphology. Subsequently, the batch generation of FE models for fractured laminated glass by adjusting surface compressive stress was established, which utilized Voronoi tessellation to approximate the actual morphology to expand the simulation dataset. The fast evaluation method based on convolutional neural network (CNN) with high accuracy for the equivalent tensile properties of fractured laminated glass was developed via image recognition training on crack morphology.

Low-Speed Impact Performance of Multi-Layer Composite PVB Laminated Glass

CHEN Zhenhai, CHENG Binghua, YANG Huiwei, CHEN Pengcheng

2024, 43(12):  4597-4607. 

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A finite element software ABAQUS was used to establish a 1/4 symmetric model of falling hammer impacting polyvinyl butyral ester (PVB) laminated glass plate, and a zero-thickness cohesion unit was inserted between grid cells of laminated glass to simulate the impact damage process of laminated glass. Under the case of a constant thickness, the effects of number of glass layers and PVB thickness on the impact resistance of laminated glass were analyzed. The results show that under the condition of constant total thickness, the effect of number of glass layers on the impact damage performance of laminated glass is more significant. Assuming that glass thickness is certain, when the PVB thickness h≤1.9 mm, the appropriate reduction of PVB thickness can improve the energy-absorbing effect of double laminated glass. When the PVB thickness h>1.9 mm, the appropriate increase in thickness of PVB can improve the energy-absorbing effect of double laminated glass. For three-layer laminated glass, the change of upper layer of PVB thickness has a more obvious effect on the impact resistance of glass, and the appropriate reduction of upper layer of PVB thickness improves the energy-absorbing effect of three-layer laminated glass.

Simulation Study on Melting Performance of Vitrification Melter with Different Electrode Connection Modes

XU Dongqing, QU Xiaorui, WANG Lei, ZHAO Qingbin, LI Luyao, XU Kai

2024, 43(12):  4608-4619. 

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Development of a reliable and accurate predictive model for the melting performance of the Joule-heating ceramic melter (JHCM) to vitrify the high-level liquid waste (HLLW) is quite crucial to safely and efficiently treat HLLW. However, due to the harsh operating conditions of HLLW vitrification, such as high temperature and high radiation, the physical field information and melting performance of the melter are not fully understood. Therefore, this work applied the GFM (Glass Furnace Model) software and numerical simulation technique to analyze the melting performance of a JHCM for HLLW vitrification under different electrode connection modes. The influences of electrode connection modes on mass transfer, heat transfer, glass flow behavior, and the distribution of various physical fields in the melter were carefully investigated. The results indicate that during standard operation, the average temperature of the glass melt is ~1 160 ℃, the average Joule heat is ~120 kW/m³, and the melting efficiency is ~0.004 kg/(m²·s). Compared to normal operation, the melter would still be able to work, when the electrodes are misaligned, but the distribution of Joule heat in the melt is uneven and the glass melt flow circulation is loose and weak, which are not beneficial for glass melting and homogenization. In this case, the risk of electrode damage will significantly increase as well.

Refractory Materials

Effect of Nano-Cr₂O₃ on Corrosion Resistance of MgO-CaO Material to Low Basicity Slag

LI Jia, LUAN Jian, PAN Bo, WANG Shushan, WANG Chunyan, ZANG Weinan, QIN Jiachen

2024, 43(12):  4620-4628. 

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Magnesium-calcium refractory is considered to be an ideal lining material for off-furnace refining equipment due to its high refractoriness, stable thermodynamic properties, and purification of molten steel. However, in the actual smelting process, it has been eroded by low basicity slag for a long time, and the melting loss is serious. Therefore, in order to improve the corrosion resistance of MgO-CaO system to low basicity slag. In this paper, light-burned dolomite powder and light-burned magnesium oxide powder were used as the main raw materials, and different amounts of nano-Cr₂O₃ (0.5%, 1.0%, 1.5%, 2.0%, 2.5% and 3.0%,mass fraction) were added. After mixing, molding and firing at 1 650 ℃×3 h, the erosion experiment of low basicity slag (m(CaO) ∶m(SiO₂)=1 ∶1) was carried out. The phase composition and microstructure of the samples after erosion were analyzed by XRD and SEM. The results show that the addition of a small amount of nano-Cr₂O₃ will dissolve into CaO and MgO grains, causing lattice distortion and promoting sintering. When the addition of nano-Cr₂O₃ exceeds 2.5%, nano-Cr₂O₃ will react with CaO and MgO to form CaCr₂O₄ and MgCr₂O₄, which are filled in the grain boundaries and other parts of the grains. The microstructure of the sample is changed, and the corrosion resistance of the sample is significantly improved.

New Functional Materials

Effects of Nanoparticles on Electrical Performance of Semi-Transparent Ultra-Thin Cu(In,Ga)Se₂ Solar Cell under Rear Illumination

PEI Hanning, LI Hangyu, XU Baoliang, YIN Guanchao

2024, 43(12):  4629-4638. 

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This research used solar cell capacitance simulator (SCAPS-1D) and COMSOL Multiphysics software to theoretically explore the effects of SiO₂ nanoparticles on electrical performance of semi-transparent ultra-thin Cu(In,Ga)Se₂ (CIGSe) solar cells. The results show that a large amount of photogenerated carriers are generated near the CIGSe/transparent conductive oxide (TCO) back interface under rear illumination, leading to a significant effect of photogenerated electron back recombination on cell performance. At a high back recombination rate (S_b=1.0×10⁷ cm/s), the introduction of SiO₂ nanoparticles at the CIGSe/TCO back interface results in a more significant effect on the reduction of photogenerated carrier concentration than the movement of space charge region, resulting in an overall reduction in back recombination current. However, the performance improvement from hole transport is overshadowed by high back recombination current. Therefore, for semi-transparent ultra-thin CIGSe solar cells under rear illumination, a low back recombination rate (passivated back interface) can improve cell performance, which is completely opposite to the conclusion that high S_b enhances cell performance under front illumination. Meanwhile, reducing the consumption of light capture due to back recombination to increase short-circuit current density is an effective way to improve cell performance. These findings represent the latest advancements in the study of rear illumination mechanisms, offering new possibilities for enhancing the performance of semi-transparent ultra-thin CIGSe solar cells.

Preparation and Properties of Ag/CuO/TiO₂/Natural Zeolite Based Composites with Visible Light Photocatalytic/Antibacterial Properties

YU Qianru, WANG Lipeng, DU Fuling, LIANG Xinchao, LIU Siqi, WANG Cheng

2024, 43(12):  4639-4648. 

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The Ag/CuO/TiO₂/natural zeolite composites were prepared by impregnation-calcination method to immobilize CuO/TiO₂ particles on the surface of natural zeolite after acid treatment, and then Ag nanoparticles were immobilized on the surface of CuO/TiO₂/natural zeolite by ion exchange/photoreduction method. The composites were further mixed with white cement and latex powder to obtain a zeolite based environmental protection coating. The composition and structure of materials were characterized by XRD, FT-IR, SEM-EDX, N₂ adsorption-desorption, UV-Vis DRS, PL and other tests. The photocatalytic and antibacterial properties of materials were evaluated by methyl orange and escherichia coli, respectively. The results show that the specific surface area of prepared Ag/CuO/TiO₂/natural zeolite composites is 146 m²·g^-1, and the light response range can be extended to 506 nm, which has a low electron-hole pair recombination probability. After 240 min of xenon lamp irradiation, the removal rate of methyl orange is 93.2%, and the antibacterial rate is nearly 100% after 5 min of irradiation.

Preparation and CO₂ Electrolysis Performance of A-Site Deficient La₆Sr_0.3Cr_0.5Fe_0.5O_3-δ Materials

CHANG Hong, NIU Jiachun

2024, 43(12):  4649-4656. 

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To further enhance the catalytic activity of the perovskite-type oxide La_0.7Sr_0.3Cr_0.5Fe_0.5O_3-δ(LSCrF), non-stoichiometric defects were introduced at the A-site of the LSCrF material to prepare A-site deficient La_0.6Sr_0.3Cr_0.5Fe_0.5O_3-δ(A-LSCrF). The physical-chemical properties and electrochemical performance of the materials were investigated using a comprehensive set of characterization techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) analysis, thermogravimetric analysis (TGA), and electrochemical testing. The results indicate that the A-LSCrF sample exhibits uniform particle sizes, with a specific surface area and mean pore diameter of 1.70 m²·g^-1 and 14.08 nm, respectively. Under operating conditions, it generates a higher concentration of oxygen vacancies, which is beneficial in boosting catalytic activity. At 2.00 V, the current density of the LSCrF-based single cell is 0.73 A·cm^-1, whereas the A-LSCrF-based single cell achieves a current density of 1.38 A·cm^-1. These findings suggest that the introduction of A-site defects effectively increases the concentration of oxygen vacancies, thereby enhancing the cell’s performance in electrochemical CO₂ reduction.