Electrically accelerated corrosion is a method to simulate the rapid corrosion of steel bars in concrete by applying electric current. This paper introduces the natural corrosion mechanism of steel bars, summarizes the characteristics, application scope, influencing factors and their influencing mechanisms of the electrically accelerated corrosion test method. The parameter selection of the electrically accelerated corrosion test in the process of simulating natural corrosion is discussed. The correlation between electrically accelerated corrosion and natural corrosion is analyzed. Finally, it is pointed out that the interaction of multiple factors affecting the accelerated corrosion of steel bar and the similarity between the electrically accelerated corrosion and natural corrosion need to be further studied.

Incorporating recycled wood fibers made from waste wood into ordinary Portland cement mortar adversely affects its hydration characteristics, mechanical properties and durability, thereby limiting the promotion and application of cement-based materials containing recycled wood fibers. In this study, using high belite cement (HBSC) as cementation material, recycled wood fiber was obtained from waste board after crushing, refining and beating treatment, and lightweight and high-toughness high belite cement mortar was prepared under forming pressure of 50.0 kN, and the mechanical properties and shrinkage properties of mortar under different water-cement ratios were studied. The results show that the lower water-cement ratio plays a positive role in improving the performance of HBSC mortar. As the binder-wood fiber ratio increases from 0.8 to 3.0, the dry density of HBSC mortar of recycled wood fiber increases continuously, and the highest is 1 408 kg/m3, the compressive strength, flexural strength and shrinkage rate of mortar increase continuously. The 28 d compressive strength of mortar increases from 15.7 MPa to 32.4 MPa, and the 28 d flexural strength increases from 6.3 MPa to 12.2 MPa. The 28 d maximum shrinkage rate of mortar under different water-cement ratios is lower than 40.0×10-5, the thermal conductivity is 0.317 6 W/(m·K), and the lightweight, high toughness, and insulation effect of recycled wood fiber high belite cement HBSC mortar are remarkable. In addition, the microscopic test results show that when the binder-wood fiber ratio is 3.0, the hydration of cement mortar is the most adequate and the internal pore structure is the most dense. This study can provide reference for the application of recycled wood fibers in lightweight, high-strength, and high-toughness insulation wall materials.

Selective catalytic reduction (SCR) denitrification is an urgent need for deep emission reduction of flue gas NOx in cement kiln. In this paper, the SCR denitrification reactor of a cement kiln with a flue gas treatment capacity of 10 000 Nm3/h was taken as the research object, and the computational fluid dynamics (CFD) numerical simulation was used to analyze and compare the different distribution modes of the reactor inlet, and the flow field optimization method in the reactor was discussed. The results show that the reasonable installation of guide plate in the middle and gradual expansion section of the reactor flue inlet, and the installation of porous uniform distribution plate at the top entrance of the reactor have excellent flow field homogenization effect. The installation of porous uniform distribution plate plays an important role. Through the optimal combination of the homogeneous distribution device, the relative standard deviation Cv of the velocity above the top layer catalyst bed in the reactor reaches 8.45%, the maximum incidence angle is 9.53°, and the overall resistance of the system increases by only 37 Pa. Furthermore, when the reserved layer of the catalyst bed is placed in the top-level design can obtain the better optimal effect of flow field, and Cv of speed can be reduced to 6.73%. This paper is expected to provide reference for further optimization design of SCR denitrification reactor of cement kiln.

Aiming at the engineering problem of concrete easy to crack, difficult to repair, and fast corrosion of reinforcement after cracking, microcapsules with tung oil (TO) as the core material, sodium alginate (SA) and nitrite-modified magnesium-aluminum hydrotalcites (NO2−-LDHs) as the wall material were prepared in this paper by using the sharp-pore solid-bath method. Three factors, namely, different TO and SA mass ratios, SA concentration, and emulsifier concentration were optimized by response surface analysis using the encapsulation rate as the response index. The polarization curves of the reinforcement were tested and the strength recovery rates of mortar specimens with microcapsules dosed at 0% and 1% (mass fraction) were compared under dry and wet cured conditions. The results show that the maximum encapsulation rate of microcapsules on TO is 74.03% when the mass ratio of TO and SA is 9∶1, the concentration of SA is 1.69% (mass fraction), and the concentration of sodium dodecyl benzene sulfonate (SDBS) is 0.95% (mass fraction). The prepared microcapsules have a certain degree of corrosion inhibition effectiveness, and the efficiency of corrosion inhibition at 6% dosing of solution mass is 93.35%. The results of self-repair experiments show that microcapsules can significantly improve the compressive strength recovery rate of mortar specimens, and the 28 d recovery rate of dry cured specimens (80%) is higher than that of wet cured specimens (76%).

In this paper, the damage degradation law and service life of mechanism sand concrete (MSC) were studied by composite salt freeze-thaw cycle test of tuff mechanism sand concrete (TMSC) and granite mechanism sand concrete (GMSC). The macroscopic indexes such as mass loss rate, relative dynamic elastic modulus, compressive strength loss rate and the microscopic indexes such as XRD and SEM were used to characterize the damage degradation law and corrosion mechanism of MSC. At the same time, the failure times of MSC composite salt freeze-thaw cycle were predicted according to the GM (1,1) prediction model. The results show that with the increase of the times of composite salt freeze-thaw cycle, the mass loss of the two kinds of MSC decreases first and then increases. The relative dynamic elastic modulus decreases gradually, and the compressive strength loss rate increases gradually. After 200 composite salt freeze-thaw cycle times, the mass loss rate of TMSC and GMSC is 1.29% and 1.75%, the relative dynamic elastic modulus is 63.30% and 58.70%, and the compressive strength loss rate is 42.16% and 45.58%, respectively. TMSC and GMSC fail after 204 and 193 composite salt freeze-thaw cycle times, respectively. The service life is 22.47 and 21.26 years, respectively. TMSC show better service life than GMSC under composite salt freeze-thaw environment.

In order to investigate the dynamic failure and energy dissipation characteristics of granite-concrete composite under high temperature, dynamic compression tests were conducted using a split Hopkinson pressure bar (SHPB) with temperature (20, 200, 400, 600 ℃) and impact velocity (8, 10, 12 m/s) as variables. The results show that high temperatures significantly reduce the dynamic compressive strength of composite, and with increasing temperature, the extent of impact fragmentation intensifies. Specifically, after heating to 600 ℃, the dynamic compressive strength of composite decreases by 39.64% or more compared to 20 ℃. The increase in impact velocity leads to higher dynamic compressive strength and energy density of composite, indicating a significant strain rate effect. The average fracture particle size is negatively correlated with impact velocity and energy density, meaning higher impact velocities result in finer particle sizes. The variation of fractal dimension reveals the effect of high temperature and impact velocity on the failure mode of composite. At 600 ℃, the fractal dimension reaches its maximum value, indicating that high temperature exacerbates the internal structural damage of composite. The research results provide valuable insights for understanding and predicting the dynamic response of rock-concrete structures in high temperature environments.

Using phosphogypsum lightweight coarse aggregate instead of natural gravel to prepare lightweight aggregate concrete is an effective technology to realize the comprehensive utilization of phosphogypsum resources. Based on the mix ratio design principle of lightweight aggregate concrete and BP neural network model, a method to predict the mechanical properties of small particle size phosphogypsum lightweight aggregate concrete was proposed. The results show that the compressive strength and splitting tensile strength of concrete decrease with the increase of net water cement ratio, increase with the increase of sand ratio, and decrease slightly with the increase of cement content. The order of significance of the three influencing factors is net water cement ratio, sand ratio and cement content. Appropriately reducing the net water cement ratio, using high sand ratio and low cement content can reduce the generation of pores and initial microcracks in the interfacial transition zone, and improve the overall mechanical strength. The constructed BP neural network model has a high accuracy in predicting the mechanical strength of small particle phosphogypsum lightweight aggregate concrete. The purpose of this study is to provide reference for mix ratio design optimization and mechanical strength prediction of phosphogypsum lightweight aggregate concrete.

Taking the replacement rate of aeolian sand, water-binder ratio, fiber volume ratio and sand-binder ratio as the research variables, the early shrinkage performance of aeolian sand polyvinyl alcohol fiber reinforced cementitious composite (PVA-FRCC) specimens was studied through the shrinkage test of 14 groups of aeolian sand PVA-FRCC specimens. The results show that with the increase of the replacement rate of aeolian sand, water-binder ratio and sand-binder ratio, the shrinkage of aeolian sand PVA-FRCC increases, and the shrinkage of the substrate decreases after the incorporation of fibers, but the further increase of the fiber volume ratio has no obvious effect on reducing the shrinkage. Taking shrinkage strain, compressive strength, ultimate tensile strain and fluidity as indexes, the comprehensive evaluation method was used to comprehensively evaluate the performance of PVA-FRCC of aeolian sand. According to the classification of general engineering, high fluidity, low shrinkage and high toughness, the better mix ratio to meet the needs of different engineering applications was proposed. Finally, the CEB-FIP model is modified, and an early shrinkage estimation model of PVA-FRCC for aeolian sand considering the influence of various factors is proposed. The calculated values of the model are in good agreement with the experimental values, which can be used for early shrinkage estimation and shrinkage cracking risk prediction of PVA-FRCC for aeolian sand.

Coal gangue shotcrete (CGS), as an eco-friendly construction material, is significantly influenced by the type and amount of admixtures used, among which accelerators and superplasticizers are widely applied due to their effective modification properties. This paper investigated the impact of varying dosages of accelerators and superplasticizers on the mechanical properties and impermeability of CGS through single-factor experiments to determine the optimal dosage. The findings were validated through rebound rate and large plate spraying tests. The results show that the inclusion of superplasticizer causes the compressive strength and splitting tensile strength of CGS to initially increase, then decrease, and rise again, achieving optimum properties at a 2.50% (mass fraction) dosage with no signs of permeability and good compactness. For accelerator content ranging from 0% to 3%, there is a slight increase in compressive and splitting tensile strength at 1 d age, which gradually decreases at 7 and 28 d. When the dosage increases from 3% to 12% (mass fraction), the strengths significantly decrease at all tested ages. Excessive accelerator (12%) notably exacerbates permeability. When the accelerator dosage is 3%, the top of CGS shows permeability. Rebound tests demonstrate that the synergistic effect of the accelerator and superplasticier enhances the flowability and bonding of CGS, reducing the rebound rate to 13.03%. The large plate spraying tests indicate that the optimized mix of CGS significantly enhances compressive strength and splitting tensile strength compared to ordinary CGS, with a 50.72% reduction in average penetration height.

In order to reduce the carbon emission and embodied energy consumption in the production process of ultra-high performance concrete (UHPC), ultra-high performance alkali-activated concrete (UHPAAC) was prepared by replacing traditional Portland cement with alkali-activated slag materials, and the effects of sodium silicate modulus (1.1, 1.3, 1.5) and alkali equivalent (6%, 7%, 8%, mass fraction) on the workability, mechanical performance and durability performance of UHPAAC were studied, and the environmental benefits were analyzed. The results show that the pore structure of UHPAAC can be refined by appropriately increasing the sodium silicate modulus and alkali equivalent, and the properties of UHPAAC can be improved. UHPAAC has a faster coagulation hardening and lower fluidity than UHPC. UHPAAC has high early strength, and the compressive strength of standard curing 7 d exceeds 100 MPa, and reaches 80.2%~92.4% of the compressive strength of 28 d. The capillary water absorption mass and water absorption of UHPAAC are significantly higher than those of UHPC, but the chloride ion permeation resistance is better than that of UHPC, and the carbonization depth is 0 mm after 28 d of carbonization under accelerated laboratory conditions. In addition, UHPAAC can significantly reduce carbon emission and embodied energy consumption. This study indicates that when the sodium silicate modulus is 1.5 and the alkali equivalent is 6%, the comprehensive performance of UHPAAC is optimal and its environmental impact is minimal.

Steel-FRP composite bar (SFCB) has the advantages of both steel bars and fiber-reinforced polymer (FRP), and its excellent corrosion resistance can be combined with coral concrete, which has a good application prospect in the development of islands in the distant sea. In order to study the flexural mechanical properties of coral concrete unidirectional slabs reinforced by SFCB, six unidirectional plate specimens were subjected to static monotonic flexural loading test with varying parameters such as the steel bar type, longitudinal reinforcement ratio and concrete type. The failure process and morphology of the unidirectional slab under force were observed, the flexural moment-deflection curves and material strain distribution of the entire force process were obtained, and the influence of variation parameter on the flexural performance of the unidirectional slabs was analyzed. The results show that the failure mode of the SFCB specimen is similar to that of the ordinary steel specimen, which belongs to the flexural failure of normal cross-section, and has stronger bending stiffness after concrete cracking, the crack development is effectively limited. Compared with odinary steel specimen, the ultimate flexural moment is increased by 8.4%, but the ductility is reduced by 12.7%. The bending stiffness and bearing capacity of SFCB specimens decrease with the decrease of reinforcement ratio, but the ductility is improved, with a maximum increase of 71.2%. The surface porousness, micro-pumping effect and brittleness of coral aggregate lead to higher bearing capacity and poor deformation ability of SFCB coral concrete slab specimen, but its failure form is similar to that of ordinary concrete slab specimen. Finally, based on the assumption of flat cross-section, the formulas for calculating the ultimate flexural moment of concrete unidirectional slabs reinforced by SFCB are derived, and the calculated values are in good agreement with the test values.

Alkali-activated materials are considered as potential alternatives to Portland cement. However, their high shrinkage rate remains a critical issue limiting widespread application. This study investigated the relationship between drying shrinkage and water loss rate of alkali-activated slag-fly ash paste. It examined the effect of fly ash content on compressive strength, reaction products, microstructure and hydration heat. The results show that with the increase of fly ash content, both drying shrinkage and water loss rate of alkali-activated slag increase. The fly ash content significantly affects the compressive strength of alkali-activated slag paste. In the early hydration stage (0~14 d), samples without fly ash exhibit higher compressive strength. However, in the later stage (14~28 d), samples with 20% (mass fraction) and 30% fly ash show a significant increase in strength. When the fly ash content is 20% and 30% and the Ca/Si ratio (molar ratio) is close to 1, it ensures strength development while reducing drying shrinkage and water loss rate.

Controlled low strength materials (CLSM) were prepared by using different proportions of ground granulated blast furnace slag (GGBS) and fly ash (FA) mixed with sandy soil and decoration wastes. This paper studied the influences of GGBS and FA dosages on the fluidity, bleeding rate, setting time and compressive strength of CLSM. The effects of GGBS and FA dosages on the phase composition and micromorphology of CLSM were explored by XRD and SEM. The results show that with the increase of GGBS and FA in CLSM, the bleeding rate decreases, and the setting time shortens. When FA dosage remains unchanged, and GGBS increases from 150 g to 270 g, the 3 d compressive strength of CLSM increases from 2.01 MPa to 4.00 MPa, and the 28 d compressive strength increases from 6.83 MPa to 11.12 MPa. When GGBS dosage remains unchanged, and FA changes from 120 g to 240 g, the 3 d compressive strength increases from 2.41 MPa to 3.13 MPa, and the 28 d compressive strength increases from 6.65 MPa to 10.24 MPa. GGBS and FA increase the compactness of CLSM as more calcium silicate hydrate (C-S-H) and calcium silicaluminate hydrate (C-A-S-H) are produced.

In order to improve the working performance and mechanical properties of coal-based solid waste filling materials, the effects of different working pressure values and stirring time on the working performance and mechanical properties of fully solid waste filling materials (abbreviated as filling material) were studied in this paper. The microscopic characteristics of filling materials under excitation stirring process were discussed by XRD and SEM. The results indicate that the performance of the filling material initially improves and then decreases with the increase of the working pressure value. When the optimal working pressure value is 0.4 MPa, the slump of the filling material prepared by excitation stirring is 30 mm higher than that prepared by ordinary stirring, and the compressive strength at 28 d is increased by 24.1%. As the mixing time is extended, the growth rate of the slump of the filling material gradually slows down. The compressive strength reaches the best performance when the filling material is subjected to 60 s of excitation dry stirring followed by 45 s of excitation wet stirring. The excitation stirring time during the wet stirring stage has a more significant impact on the performance of the filling material. Adding a standing time during the stirring process leads to some deterioration in the overall performance of the filling material, but it can still meet the construction requirements. Excitation stirring process can enhance the early hydration degree of the filling material, strengthen the bonding between the cementitious materials and aggregates, and improve the density of hydration products, thereby enhancing the macro-mechanical properties of the filling material.

In order to slove the environmental pollution problem caused by sulfur-containing lead-zinc tailings, this study adopted microbial induced calcuim carbonate precipitation technology to solidify and remediate the tailings through the synergistic action of S. pasteurii and sulfate-reducing bacteria. By simultaneously optimizing the formula of the composite nutrient solution, it is found that ammonium bicarbonate is the optimal carbon source, and the best results achieve when the calcium source concentration is 0.50 mol/L. The results show that the unconfined compressive strength of the composite nutrient solution specimen is 1.075 MPa and the calcium carbonate content is 13.03%. Compared with the basic nutrient solution of the same concentration, unconfined compressive strength and calcium carbonate content have increased by 27.33% and 29.21%, respectively. Additionally, the curing effect of heavy metal ions and sulfate ions is remarkable, with Pb2+, total Fe, total Cr, Cd2+, Cu2+, and Mn2+ being completely removed, the curing rate of Zn2+ exceeding 98%, and the curing rate of SO42− is up to 88.68%. Microscopic analysis reveals that the solidified samples formed highly cohesive crystals such as aragonite and calcite, effectively binding the tailings particles together. This study offers a novel approach for the solidification and remediation of sulfur-containing lead-zinc tailings.

Straw fiber and steel slag are typical agricultural and industrial by-products, respectively. By preparing foamed concrete, straw fiber and steel slag can be prepared into biomass low-carbon building materials to realize resource recycling. In this study, steel slag was used as the main cementitious material, and rice straw fiber was added to prepare straw fiber reinforced alkali-activated steel slag-based foamed concrete. The effects of hydrogen peroxide content, straw content and curing conditions on compressive strength, thermal conductivity, pore structure and CO2 sequestration of straw fiber reinforced alkali-activated steel slag-based foamed concrete were studied. The results show that the hydrogen peroxide content can effectively adjust the bulk density, compressive strength and thermal conductivity of the straw fiber reinforced alkali-activated steel slag-based foamed concrete, and the straw fibers can increase the pore connectivity and facilitate the internal diffusion of CO2. At the same time, the mechanical properties of straw fiber reinforced foamed concrete need to balance the two effects of matrix enhancement and pore structure destruction.

This study utilized lithium slag and mineral powder to prepare alkali-activated composite cementitious materials, aimed at addressing the disposal issues of lithium slag and reducing the energy consumption and CO2 emissions from cement production. The research primarily analyzed the effects of water-binder ratio and lithium slag content on the rheological properties of materials, and further explored the effects of different calcination temperatures and lithium slag content on the mechanical properties of materials. The findings indicate that the fluidity of the alkali-activated lithium slag composite cementitious materials increases with the water-binder ratio, but decreases as the lithium slag content increases. The optimal calcination temperature for lithium slag is 700 ℃, under which the alkali-activated lithium slag composite cementitious materials exhibit the best flexural and compressive strength at 90 d. 25% (mass fraction) lithium slag content is the optimal proportion for the alkali-activated composite cementitious materials, as excessive content inhibits the hydration reaction. Compared to traditional cement clinker, the alkali-activated lithium slag composite cementitious materials significantly reduce CO2 emissions and energy consumption.

The conventional alkaline solution activator has high corrosion and viscosity, which limits the large-scale application of alkali-activated technology in fly ash disposal. It is very important to select appropriate solid activator for the preparation of cementitious materials. One-part alkali-activated slag-fly ash composite cementitious material was prepared in this paper. The effects of different solid activators on the mechanical properties and hydration products of cementitious material were discussed in order to find a more effective fly ash treatment solution. The results show that sodium silicate pentahydrate can improve the early strength of cementitious material, and the additional silicon source promotes the formation of silicon-oxygen tetrahedron, which is conducive to the formation of network hydrated calcium aluminosilicate gel. Calcium oxide has a significant effect on the growth of later strength. The maximum compressive strength of cementitious material at 28 d is 28.90 MPa. The higher alkalinity can make the silicon-aluminum phase continue to dissolve and produce more effective polymerization. The heavy metal leaching concentrations in the cementitious material activated by sodium sulfate, sodium silicate pentahydrate and calcium oxide all meet the standard allowable values. The dense gel structure is conducive to the fixation of heavy metals, reducing cracks and pores, and further reducing the leaching amount of heavy metals.

In order to improve the utilization rate of solid waste, hydrochloric acid, acetic acid and oxalic acid were respectively selected as acid activators to impregnate and excite fly ash and slag micro-powder, subsequently prepareing grouting materials. The optimal excitation concentration of acid activator was determined by measuring the mechanical properties of grouting materials. The specimens were placed in standard curing environment, 3% (mass fraction) NaCl solution, 3% (mass fraction) Na2SO4 solution, 3% (mass fraction) NaCl and Na2SO4 mixed solution for curing for 28 d, respectively. The corrosion resistance coefficient was calculated by measuring the flexural strength of the specimen, and the corrosion resistance of the grouting material prepared after acid excited solid waste in different corrosion environments was analyzed comprehensively combined with the microstructure of the specimen. The results show that after the grouting material specimens prepared by soaking and exciting fly ash and slag in a 2.0% (mass fraction) hydrochloric acid solution, the compressive strength is the highest, which can reach 64.5 MPa. The contents of quartz and ettringite in the grouting material prepared after acid excitation of fly ash and slag increase, and acid excitation can promote the hydration reaction to a certain extent. The grouting material specimens prepared by hydrochloric acid excitation have the poorest resistance to the erosion of Cl- and can resist the erosion of SO42− to a certain extent.

In order to realize the green and low-carbon reuse of engineering muck, the effects of slag, fly ash and glass powder content on the mechanical properties of solidified soil at different ages (3,7,14,28 d) were studied. The microstructure and hydration products of solidified silt soil were analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD), and the curing mechanism was revealed. The results show that the early strength of slag-fly ash and slag-glass powder composite solidified soil increases with the increase of slag content. When the proportion of slag is 50% to 60% (mass fraction), the early strength of slag-fly ash-glass powder ternary composite solidified soil can be effectively improved by increasing the content of glass powder. The error of unconfined compressive strength prediction model of solidified soil established by simplex centroid method is within 10%. Slag-glass powder composite solidified soil shows higher cohesion than slag-fly ash solidified soil at low slag content. The slag-fly ash-glass powder ternary composite curing system significantly improves the compactness of soil, and generates hydrated sodium aluminosilicate, hydrated calcium silicate and hydrated calcium aluminosilicate gel. These hydration products pack and bond the soil particles and improve the mechanical properties of solidified soil.

The problem of resource waste and environmental pollution caused by circulating fluidized bed fly ash (CFBFA) is becoming increasingly acute, and its resource utilization is imminent. In this paper, carbide slag (CS) and desulfurized gypsum (DG) were used to synergistically activate CFBFA and granulated blast furnace slag (GBFS) to prepare low-carbon cementitious materials and apply them to pavement concrete. The results indicate that with the increase of CFBFA content, the mechanical strength of CFBFA-GBFS composite cementitious materials at 3 and 7 d decreases gradually. At the age of 28 d, the mechanical strength of CFBFA-GBFS composite cementitious materials initially increases and subsequently decreases. When the CFBFA content is 40% (mass fraction, the same below), the 28 d flexural strength and compressive strength of CFBFA-GBFS composite cementitious materials are the highest, which are 7.4 and 32.8 MPa, respectively. When the CFBFA content is increased from 30% to 70%, the initial setting time of CFBFA-GBFS composite cementitious material is extended from 447 min to 753 min, and the final setting time is extended from 549 min to 802 min. The 28 d drying shrinkage of the specimen is the largest when the CFBFA content is 50%, which is 0.031%, respectively. The hydration products of CFBFA-GBFS composite cementitious materials mainly include hydrated calcium aluminosilicate (C-A-S-H) gel and ettringite (AFt). The interlaced growth of C-A-S-H gel and needle-like AFt in space refines the internal pores of the material, which is conducive to the improvement of strength. The 28 d flexural tensile strength and compressive strength of pavement concrete can reach 4.8 and 43.0 MPa, respectively, which meet the standard of intermediate load pavement concrete.

An green ultrafine and high active mineral admixture was developed through the synergistic utilization of various industrial solid wastes. This study systematically investigated the effects of raw material ratios and milling parameters on the performance of admixture, with hydration products and microstructural characteristics analyzed using XRD, TGA, and SEM techniques. The results demonstrate that when water quenched manganese slag, steel slag, fly ash, and desulfurization gypsum are mixed in a mass ratio of 8∶3∶8∶1 with 0.10% (mass fraction) of a milling aid and jointly ground to a specific surface area of 800 m2/kg, the admixture achieves a 7 d activity index of 97.4% and a 28 d activity index of 110.0%, along with a flowability ratio of 95.1%. In the early stage, the admixture minimizes strength loss through physical filling and the formation of calcium aluminate hydrates, while in the later stage, synergistic hydration and pozzolanic reactions enhance strength development. The research results are of great significance for realizing high value-added utilization of low active solid waste and sustainable development of building materials industry.

The low efficiency of dry carbonization for recycled concrete sand powder (RCSP) limits the utilization of RCSP resources. In this paper, the effects of wet carbonization treatment on the properties of RCSP and the influence of RCSP on the hydration and properties of cement paste at different replacement ratios were investigated. The results show that the CaCO3 content in the wet carbonization recycled sand powder (WRCSP) is as high as 77.06% (mass fraction), and the CO2 sequestration amount amounts to 0.53 kg CO2 absorbed by each kilogram of RCSP. When the replacement ratio of WRCSP is 20% (mass fraction), 7 d compressive strength of cement paste is 45.3 MPa, showing increases of 76.3% and 4.61% compared to RCSP and PC, respectively. The main carbonization products of WRCSP are polycrystalline calcium carbonate and high polymerization silica gel, which can react with the hydration products of the cement, accelerate the early hydration of the cement, and significantly enhance the early mechanical properties of the cement. In summary, the higher the carbon fixation capacity after wet carbonization treatment is, the better the performance of WRCSP as a substitute for cement is. This conclusion verifies the feasibility of wet carbonization of RCSP and provide reference for future industrial applications.

To investigate the impact of diesel microemulsion on the flotation effectiveness of a fine flake graphite mine in Luobei area, the diesel microemulsion was prepared by high-speed stirring method, with Span 80 and Tween 80 as emulsifiers, n-butanol as co-emulsifier and diesel oil at the mass ratio of 2∶1∶1, and the flotation effect was analyzed. The results show that: Using the traditional graphite beneficiation process of stage grinding and flotation, and comparing the rough concentrate flotation tests with diesel and diesel microemulsion as collectors, when the same concentrate recovery rate is obtained, the oil-saving rates of diesel microemulsion are 25.11% and 50.43%, respectively. In the open-circuit experiments, the oil-saving rate of diesel microemulsion is 28.83%. Therefore, the flotation performance of diesel microemulsion is significantly better than that of diesel. In the standing time flotation test, the diesel microemulsion can be stored for at least 40 d, and the microemulsion has good stability, which can solve the problem of drug storage in industrial production. Among the economic benefits, the cost of collector of diesel microemulsion required for selecting 1 t of graphite is only 81.91% of that of diesel. Diesel microemulsion can not only improve the flotation index of fine flake graphite, but also reduce the dosage of collector and the cost of reagents used for flotation.

Compared with organic sealing, inorganic glass sealing has the characteristics of high electrical insulation, good air tightness and long life, and is widely used in aviation, aerospace, electronics and new energy vehicles. Low-temperature sealing glass is glass with a sealing temperature below 600 ℃. Currently, low-temperature sealing glass systems mainly include plumbate glass, phosphate glass, vanadate glass, and bismuth glass. The related research mainly involves exploring the ‘composition-structure-performance’ constitutive relationship of low temperature sealing glass, which provides theoretical guidance for the design and optimization of new low-temperature sealing glass system. The key properties such as coefficient of thermal expansion, transition temperature and chemical stability of low-temperature sealing glass are evaluated to achieve matching sealing and long life service. To establish a standard specification for the performance test of low-temperature sealing glass materials and expand the application scenarios of low-temperature sealing glass. This paper reviews the typical systems of low-temperature sealing glass, introduces the application scenarios of low-temperature sealing glass, and finally looks forward to the development trend of low-temperature sealing glass.

The secondary pull-down process is an important process for preparing flexible radiation-resistant glass. However, it is difficult to accurately obtain the drawing characteristics of glass using secondary pull-down process and quickly adjust the process parameters. In this paper, the finite element simulation of ANSYS Polyfolw software was combined with actual drawing process parameters to simulate the changes of thickness field, velocity field and temperature field. The influences of secondary pull-down process parameters on the width and thickness of flexible glass after forming were analyzed and verified. The results show that in heating zone, the necking phenomenon causes the edge thickness of formed glass to be larger than center thickness, and the edge velocity component of glass along tensile direction is significantly smaller than center velocity component. In cooling zone, the glass edge temperature is significantly higher than center temperature. It is found that the heating temperature is positively correlated with the thickness of formed glass, and negatively correlated with width. The traction speed is negatively correlated with the thickness and width of formed glass. The initial thickness of glass is positively correlated with the thickness of formed glass, but negatively correlated with width.

The preparation of porous ceramics by pore-forming agent method has the advantage of green environmental protection, but how to balance the relationship between apparent porosity and compressive strength has become an important issue in the preparation porous ceramics. To address this issue, this study used silicon carbide (SiC) as aggregate, charcoal and industrial-grade guar gum particles as pore-forming agents, and optimized the process to prepare environmentally friendly and high-performance filter ceramics. By designing pore-forming agents with special morphology, adjusting the proportion of pore-forming agents in the slurry and optimizing sintering temperature, the apparent porosity and compressive strength of SiC porous ceramics were effectively balanced. The results show that when the number ratio of pore-forming agent particles with pore channels to those without pore channels is 1∶3, the mass fraction of methylcellulose is 1.3%, and the sintering temperature is 1 450 ℃, the obtained SiC porous ceramics have an apparent porosity of 81.24% and a compressive strength of 1.29 MPa.

To achieve the high-value utilization of aluminum dross solid waste resources, this study introduced aluminum dross as a substitute material for -Al2O3 in low carbon Al2O3-C refractory materials. Using tabular corundum, flake graphite, aluminum powder, and silicon powder as the primary raw materials, low carbon Al2O3-C refractory materials were fabricated. The effects of substituting -Al2O3 with aluminum dross on the microstructure, oxidation resistance, erosion resistance, and thermal shock resistance of the materials were investigated. The results indicate that after carbon-buried heat treatment at 1 400 ℃, the substitution of -Al2O3 with aluminum dross leads to a reduction in bulk density and an increase in apparent porosity. However, it also promotes the formation of a SiC whisker network structure inside the material, thereby enhancing the microstructure of the material. In oxidation experiments, compared to the use of -Al2O3 as an additive, adding aluminum dross is more conducive to the formation of the mullite phase. After adding aluminium dross, the appropriate amount of liquid phase generated at high temperature can effectively fill the pores of the oxide layer on the material surface, thereby improving the material's oxidation resistance, erosion resistance, and thermal shock resistance. Specifically, the oxidation index decreases from 88% to 52%, the corrosion index experiences a marked reduction, and the residual strength ratio increases from 87% to 97%.

Palygorskite is a hydrous magnesium-aluminum-silicate clay mineral, featuring a distinctive chain-layered crystal structure. It demonstrates outstanding application performance in numerous domains such as colloids, catalysis, and adsorption. In this research, various types of acids were employed to modify palygorskite, regulating its structure by dissolving the cations in the octahedral layer. With Cu2+ as the target contaminant, the effect laws of diverse modification conditions on the adsorption of Cu2+ by palygorskite were investigated via static adsorption experiments. The structures of palygorskite before and after modification were characterized via X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), N2 adsorption, solid-state nuclear magnetic resonance (NMR), and thermogravimetry (TG). The research findings indicate that after acid modification, the impurities in palygorskite decrease and micropore volume increases, significantly enhancing the adsorption capacity for Cu2+. Moreover, the HCl modified palygorskite achieves the best adsorption effect under the conditions of a reaction time of 120 min, a reaction temperature of 60 ℃ and a solution pH value of 7, and maximum adsorption capacity is 70.64 mg/g. The results of this study hold significant research implications for the application of palygorskite in the field of environmental governance.

Magnetic Fe3O4 nanomaterials have excellent magnetic properties including high magnetic response, superparamagnetism and biocompatibility. By regulating the microscopic morphology of the materials, it is possible to achieve effectively control of its physical and chemical properties, such as energy storage, catalysis and medicine, in accordance with the requirements of practical applications. In this paper, according to modify the conditions including the ratio of Fe3+ and Fe2+ in the precursor, reaction temperature and reaction time, spherical magnetic Fe3O4 nanoparticles with particle sizes ranging from 10 to 25 nm were synthesized by a facile hydrothermal method without the addition of a morphology modifier. And the saturation magnetization intensity of the material under the optimum conditions was 73.3 emu·g-1. The results show that the magnetic properties of Fe3O4 nanoparticles have a clear relationship with the preparation conditions. With the increase of hydrothermal temperature and time, the particle size and saturation magnetization intensity of magnetic nanoparticles increase first and then decrease. The smaller the particle size is, the smaller the internal magnetic effective volume is, and therefore the lower the saturation magnetization intensity is.

In order to further improve the property of light emitting diode, the development of trichromatic phosphors is very crucial. In this paper, Ba3Y1-x(BO3)3∶xTb3+ phosphors were synthesized by high temperature solid state reaction method. The phase composition was analyzed by X-ray diffraction (XRD). In addition, the luminescent properties were studied by excitation-emission spectra, CIE 1931 chromatic coordinate and fluorescence lifetime. The results show that the crystalline structure of Ba3Y(BO3)3 is not changed obviously by doped by Tb3+, which indicate that Y3+ is replaced by Tb3+ in the crystal. The maximum peak of Ba3Y1-x(BO3)3∶xTb3+ phosphors locate at 543 nm after excited by a wavelength of 283 nm ultraviolet light. The luminescence intensity of the phosphors increases firstly and then decreases with the increase of Tb3+ doping concentration at 543 nm. The luminescence intensity of sample is the greatest when the Tb3+ doping concentration is 6% (mole fraction). Meanwhile, the energy transfer style between two Tb3+ is dipole-dipole interaction. After calculation, the colour purity of Ba3Y1-x(BO3)3∶xTb3+ (x=0.02, 0.04, 0.06, 0.08 and 0.10) phosphors are all more than 92% and their colour temperature are all in 5 000 to 6 000 K, which show that the Ba3Y1-x(BO3)3∶xTb3+ phosphors are green phosphors suitable for ultraviolet light excitation, and they may have potential applications in solid state lighting.

TiO2∶Sm3+ nanofibers were prepared by electrospinning technology, and Bi/TiO2∶Sm3+ composite fibers were synthesized by in-situ hydrothermal method under the action of sodium gluconate. The phase and composition of samples were characterized by XRD and XPS. The microstructure of samples was observed by SEM and TEM. The photoelectric properties of samples were analyzed by UV-Vis diffuse reflectance spectroscopy and transient photocurrent. The results show that Sm3+ enters the TiO2 lattice and occupies the position of Ti4+, resulting in the expansion and distortion of TiO2 lattice. The lattice defects introduced by rare earth doping can increase the Fermi level of TiO2, increase the surface energy barrier, and reduce the recombination probability of photogenerated electrons and holes on the surface. Metal Bi, through the surface plasmon resonance effect, combined with the rich energy level structure and 4f electron transition characteristics of rare earth elements, the double modification of TiO2 is carried out to further improve the photocatalytic activity and stability of TiO2. Under visible light irradiation for 5 h, the degradation effect of Bi/TiO2∶Sm3+ composite fiber for lomefloxacin is the best, reaching 97.37%, which is 1.7 times and 1.3 times that of Sm3+∶TiO2 and Bi/TiO2, respectively.

Evaluating the reinforcement effect of loess foundation involves determining the compressive strength characteristics of cement-solidified loess, which serves as the basis for analysis. Using high fill loess in Yan'an New Area as the subject, the unconfined compressive strength tests and direct shear tests were conducted under various conditions to analyze the effects of cement content, curing age, compaction degree, moisture level, and immersion environment on unconfined compressive strength. The correlation between compressive strength, and shear strength, deformation modulus of cement-solidified loess was investigated. The findings indicate the occurrence of oblique cracks at 30°~40° angles in cement-solidified loess following compression failure, demonstrating brittle failure characteristics. The stress-strain curve of cement-solidified loess exhibits a strain-softening behavior, encompassing elastic stage, plastic yield stage, stress decay stage, and residual stability stage. The unconfined compressive strength of cement-solidified loess demonstrates a linear increase with higher cement content, longer curing age, and greater compaction degree. However, the rate of increase gradually diminishes as these factors escalate. Additionally, the unconfined compressive strength decreases exponentially with initial water content. The unconfined compressive strength of cement-solidified loess decreases under water immersion condition, and the unconfined compressive strength of the samples after water immersion is more than 26% lower than that before water immersion. Furthermore, there is a linear correlation between the unconfined compressive strength of cement-solidified loess and shear strength as well as deformation modulus. The cohesion represents approximately 20%~30% of unconfined compressive strength, and the deformation modulus is 23~250 times of unconfined compressive strength.

In this study, the effect of polypropylene fiber (PPF) collaborative carbonation curing technology on the 7 d shear strength and failure mode of cement soil was discussed. The shear properties and carbon sequestration characteristics of cement soil with different PPF content and different curing conditions were tested by triaxial shear test, phenolphthalein method and thermogravimetric analysis. The results show that under the standard curing condition, the shear strength of cement soil increases with the increase of PPF content, and reaches the maximum value of 2 174 kPa when the fiber content is 0.9% (mass fraction). Under the carbonation curing condition, the shear strength of cement soil increases first and then decreases with the increase of fiber content, and reaches the maximum value of 4 477 kPa when the fiber content is 0.6%. Compared with standard curing, carbonation curing has a certain improvement effect on cohesive force, but the improvement effect on internal friction angle is more significant, and the internal friction angle is less affected by fiber content. The average carbonization depth of the sample cured for 7 d is 0.85 mm, and the carbon sequestration amount is 2.5% (mass fraction).

Geopolymer is a new type of silica-aluminium material with amorphous three-dimensional network structure, which is obtained by appropriate process and chemical reaction with SiO2 and Al2O3 as main components. Using geopolymers to partially replace cement for soil solidification not only reduces the amount of cement, but also improves the strength and durability of solidified soil. In this study, fly ash-based geopolymer was used to partially replace cement to solidify powdery soil. The effects of different curing agent ratios, proportion of fly ash-based geopolymer replacing cement, water content, and curing time on the unconfined compressive strength of solidified soil were investigated. The results show that the curing effect of fly ash-based geopolymer partially replacing cement on soil is significantly improved. When the curing agent content is 8%~15% (mass fraction), the unconfined compressive strength of the solidified soil is greater, and the strength growth rate is faster. With the increase of the proportion of fly ash-based geopolymer replacing cement, the unconfined compressive strength of solidified soil increases first and then decreases. When the water content is 28%, the proportion of fly ash-based geopolymer is 5% (mass fraction), and the curing time is 60 d, the unconfined compressive strength of solidified soil reaches the maximum value. When the proportion of fly ash-based geopolymer is 10% and 15% (mass fraction), the unconfined compressive strength of solidified soil increases first and then decreases with the increase of water content. When the proportion of fly ash-based geopolymer is 0% and 5% (mass fraction), the unconfined compressive strength of solidified soil decreases with the increase of fly ash-based water content. With the increase of fly ash-based geopolymer content, the stress-strain curve slope of solidified soil first increases and then decreases.

Due to the lack of strength and easy shrinkage of cement stabilized recycled aggregate, the application of old concrete pavement crushing and recycling technology is limited. In order to improve the properties of cement stabilized recycled aggregate, this paper introduced steel slag and fly ash to study the synergistic effect, and analyzed the influence of different content of steel slag and fly ash on the mechanical strength and road performance of cement-based fly ash stabilized steel slag recycled aggregate (CFSSR). The results show that steel slag and fly ash have significant effects on the mechanical properties and road performance of recycled base materials. Specifically, with the increase of steel slag and fly ash content, the unconfined compressive strength and splitting tensile strength of CFSSR increase and then decrease. When the content of steel slag and fly ash is 50% and 16% (mass fraction), the 7 d unconfined compressive strength of CFSSR reaches the maximum value of 4.72 MPa, which is 25.20% higher than that of ordinary cement stabilized recycled aggregate. In addition, steel slag and fly ash also significantly reduce the dry shrinkage of the material, although the temperature shrinkage is slightly adverse, but the overall shrinkage is effectively reduced. Under the optimal content, a large number of needle-rod ettringite and C-S-H gel are formed in CFSSR, which interweave and fill the void, enhance the compactness of the structure, and produce a synergistic enhancement effect. This paper provides a scientific basis for the application of steel slag as base material in highway maintenance engineering.