In the construction of marine engineering, raw materials such as sea sand and coral sand are rich in certain chloride salts. During the preparation process, chloride ion in raw materials enters the interior of reinforced concrete, causing internal erosion and leading to the failure of reinforced concrete structures. A large number of experiments show that the cement hydration products C-S-H gel and Friedel’s salt play an important role in improving endogenous chloride ion binding capacity of cement-based materials and reducing the risk of rebar corrosion. The presence of cement minerals, admixtures and AFm-like phase materials affect the formation of C-S-H gel and Friedel’s salt, which in turn changes the chloride ion binding capacity of cement-based materials. This article reviews the changes of C-S-H gel and Friedel’s salt under the above influences, and then analyzes the endogenous chloride ion binding effect in cement concrete, which provides a reference for the use of chloride ion binding materials to solve the problem of chloride ion erosion in reinforced concrete.

Sulfate attack is an important factor affecting the durability of concrete. In order to further improve the sulfate attack resistance of high belite sulfate-aluminate cement (HB-CSA) based concrete, the granulated blast-furnace slag (GBFS) was added into HB-CSA to improve the sulfate attack resistance of HB-CSA. Corrosion resistance coefficient was used to evaluate the effect of slag on the sulfate attack resistance of HB-CSA mortar. Combined with X-ray diffraction analysis, thermogravimetry, mercury injection, scanning electron microscope and other testing methods, the mechanism of sulfate attack resistance was studied from the microscopic level. The results show that slag can improve the sulfate attack resistance of HB-CSA, and its corrosion resistance coefficient increases to 1.51. In the process of GBFS-HB-CSA resistance to sulfate attack, slag particles play a major role in the filling and refining of the cement pore structure of HB-CSA. SO2-4 and Ca(OH)2 jointly stimulate the hydration of Al2O3 and SiO2 in the slag to produce gel and ettringite (AFt). The gel and AFt fill in the slurry pores to refine the pore size of the slurry, which makes the slurry structure dense and reduces the ionic permeability, thus improving the ability of HB-CSA to resist sulfate attack.

Carbonation curing cement-based materials can improve the properties of cement products while permanently sequestering CO2, which is considered to be a very promising carbon reduction technology. In this paper, cement pastes with different pore structures were prepared by changing the water-cement ratio (w/c=0.35, w/c=0.4, w/c=0.45) and pre-conditioning time (2, 4, 6, 8, 16, 24, 48 and 72 h), and the influences of pore structure and water content on the carbonation reaction of cement paste were studied. The results show that the carbon sequestration rate of cement paste with different water-cement ratios reaches the maximum when the pre-conditioning time is 8 h, and the carbon sequestration rate increases with the increase of water-cement ratio. At the same time, for cement paste with early hydration (24 h standard curing+8 h pre-conditioning), the influence of water-cement ratio on the pore structure is much greater than the degree of hydration. The cement paste with initial water-cement ratio of 0.45 undergoes 8 h pre-conditioning and then undergoes 8 h carbonization curing. Its carbon sequestration rate, carbonation depth and compressive strength reach 20.35% (mass fraction), 12.49 mm and 61.99 MPa, respectively, which increases the compressive strength by 14.27% compared with the strength of the 28 d standard curing test block (54.25 MPa). The main products of carbonation reaction are CaCO3 and silica gel. The filling of CaCO3 optimizes the pore structure of cement paste, significantly reduces the pores larger than 50 nm, and the main crystal forms of CaCO3 are calcite and aragonite.

In this paper, emulsified asphalt powder (EAP), VAE redispersible polymer powder, and SBA emulsion as admixtures were mixed into the cement mortar. Cement mortar strength, water absorption and SEM analysis before and after heat treatment were used to investigate the effect of addition of the three polymers on heat aging resistance of cement mortar at 70 ℃. The results show that the addition of three polymers can all decrease the water absorption, and the water absorption decreases with the increase of polymer content. The film-forming property of SBA emulsion is better than that of redispersible polymer powder, so its modified-mortar has the best surface waterproof effect. Compared with VAE, the effect of EAP on mortar waterproofing modification is better after heat treatment. After heat treatment, asphalt component has certain viscous flow at high temperature, and the compressive strength of EAP-modified mortar decreases after heat treatment, and the flexural strength increases first and then decreases with the increase of EAP admixture, and its strength changes mainly reflect the characteristics of asphalt components under high temperature, while those VAE-modified mortar and SBA-modified mortar mainly reflect the characteristics of traditional polymer modified mortar, the polymer film structure hinders moisture migration at the early stage of heat treatment, and the flexible polymer film structure breaks down at the later stage of heat treatment causing strength higher than that before thermal aging.

The effect of temperature rising inhibitor (TRI) on early hydration process of cement-fly ash-slag composite cementitious material was studied. By changing mass proportion of mineral additives in gel materials and amount of TRI, the hydration characteristics of cementitious materials were measured. The reaction rate constant, geometric crystal growth index and other dynamic parameters were calculated based on the Krstulovic-Dabic model. The results show that mineral additives and TRI delay the time of hydration and reduce the maximum hydration rate of cementitious materials. The hydration process of composite cementitious material can involve three stages, i.e. nucleation and crystal growth, interactions at phase boundaries and diffusion. The hydration process can be predicted by Krstulovic-Dabic model well. Mineral additives and TRI affect the crystallization of nucleation and crystal growth, and reduce the hydration rate of composite cementitious material at every stage.

High performance lightweight concrete (HPLC) characterized by low density, high strength and good durability, has prosperous application prospects in civil engineering. In this experiment, the modified Andreasen and Andersen model was used to design the initial mixture of HPLC. Shale ceramic sand (SCS) with different content was used to replace lightweight internal curing sand to prepare HPLC. The effect of different content of SCS on workability, mechanical properties and durability of HPLC were systematically investigated. In addition, this work explored the effect of SCS on the micro-morphology and pore structure of HPLC. It is found that: 1) When the replacement rate of SCS is 100%, the apparent density of HPLC is 1 848.3 kg/m3, and its compressive strength is 123.22 MPa. 2) The addition of SCS can improve the mechanical properties of HPLC, and the compressive strength, flexural strength and elastic modulus of HPLC increase by 8.88%~47.92%, 22.50%~56.30% and 3.49%~14.03%, respectively. 3) SCS can improve the durability of HPLC. When SCS replacement rate is 100%, the chloride migration coefficient of HPLC is reduced by 32.52%, compared to the control group. 4) Due to the addition of SCS, the microstructure of HPLC is significantly improved, and the porosity of HPLC reduces by 14.86%~28.24%.

The soil and groundwater in Northwest China contain a large number of aggressive sulfate ions, magnesium ions and chloride ions, which leads to the durability degradation of in-service recycled aggregate concrete (RAC), and seriously restricts the use of RAC in new structures in Northwest China. In order to study the durability degradation law of RAC with multiple cementitious materials system subjected to compound salt erosion, the durability failures of different parts of RAC structural components were simulated by three modes: full immersion, partial immersion, alternating dry and wet immersion, and the durability tests of compound salt erosion of RAC were carried out. Taking the relative dynamic elastic modulus, weight loss rate and relative compressive strength as the indicators, the durability degradation law of RAC subjected to compound salt erosion under different erosion modes was studied, and the influences of the matching mode and replacement rate of supplementary cementitious materials in multiple cementitious materials system on the durability degradation law of RAC were analyzed. Under the full immersion mode, the relative dynamic elastic modulus of fly ash-slag double-mixed RAC decreases slowly. Under the partial immersion mode, the introduction of supplementary cementitious materials reduces the resistance of RAC to compound salt erosion. Under the alternating wet and dry immersion mode, the physical and mechanical properties of RAC increase first and then decrease, and the multiple cementitious materials system RAC shows better resistance to salt erosion than that of pure cement RAC.

In order to study the compressive behavior of carbon fiber recycled aggregate concrete (CFRAC) under cyclic loading, 40 cylindrical specimens were designed and fabricated for cyclic loading test with recycled coarse aggregate replacement rate, carbon fiber volume content and loading rate as variation parameters. The test observed the failure mode of the specimen, obtained the stress-strain curve, and analyzed the influences of different variation parameters on the mechanical behaviors such as peak stress, peak strain, plastic strain, stiffness degradation and stress degradation. The results show that the carbon fiber recycled aggregate concrete specimens mainly undergo oblique splitting failure under cyclic loading. The incorporation of carbon fiber improves the cyclic compression performance of recycled aggregate concrete. Compared with unmixed carbon fiber concrete, when the volume content of carbon fiber is 0.3%, the peak stress and peak strain increase by 11.33% and 12.22%, respectively. The degree of stiffness degradation and stress degradation is reduced. When the replacement rate of recycled coarse aggregate is 100%, the peak stress and peak strain increase by 10.16% and 14.29%, respectively. Finally, the stress-strain constitutive equation of carbon fiber recycled aggregate concrete under cyclic compression is proposed.

To improve the fracture performance of recycled aggregate concrete (RAC), the effects of steel fiber, sisal fiber, and steel-sisal hybrid fiber on the fracture performance of RAC specimens were studied through three-point bending fracture tests. At the same time, digital image correlation (DIC) technology was used to measure the entire process of crack propagation in RAC specimens. The results show that the fracture performance of RAC specimens without fiber addition is poor, while the fracture performance of RAC specimens with fiber addition is significantly improved. When steel fiber is single doped, the cracking toughness is not related to fiber content. When sisal fiber is single doped, the optimal volume content is 0.15%, the initiation load of RAC specimen is 67% higher than that of RAC specimen without fiber addition. Both single doped and hybrid fiber can improve instability toughness and fracture energy, but hybrid fiber has a better effect. When steel fiber with a volume fraction of 1.0% and sisal fiber with a volume fraction of 0.30% are mixed, initiation toughness, unstable toughness and fracture energy of RAC specimens increase by 83.92%, 575.86%, and 1 244.05% compared with RAC specimen without fiber addition, respectively.

Based on the self-developed steel fiber position device that can accurately control the spatial position of steel fiber, the effects of steel fiber embedded depth, diameter and embedded angle on the pull-out behavior of steel fiber in ultra-high performance fiber reinforced concrete (UHPFRC) were studied. The results indicate that the maximum pull-out force, pull-out work, maximum pull-out stress and strength utilization rate of steel fiber increase with the increase of steel fiber embedded depth. However, the maximum average bond strength decreases with the increase of steel fiber embedded depth. With the increase of steel fiber diameter, the maximum pull-out force, pull-out work and maximum average bond strength of steel fiber increase correspondingly, while the strength utilization rate and maximum pull-out stress of steel fiber decrease. With the increase of steel fiber embedded angle, the maximum pull-out force and pull-out work of steel fiber increase first and then decrease. The maximum pull-out force and pull-out work reach the maximum value at 45° and 30° of embedded angle, respectively. When the embedded angle is 75°, the failure mode of specimen is that the steel fiber is broken.

The mechanism sand concrete with strength grade C50 was designed, and the influences of stone powder content and mother rock type on compressive strength, slump and microscopic performance of mechanism sand concrete were studied. Through EDS energy spectrum analysis, XRD and SEM, the influence mechanisms of stone powder content and mother rock type on performance of mechanism sand concrete were revealed. The results show that the mother rock type has less influence on compressive strength of mechanism sand concrete. With the increase of stone powder content, the compressive strength of mechanical sand concrete increases first and then decreases. When the stone powder content is 9% of the total mass of mechanism sand, the compressive strength of limestone mechanism sand concrete is the best, which is 69.6 MPa. When the stone powder content is 6%, the compressive strength of dolerite mechanism sand concrete is the best, which is 66.0 MPa. When the stone powder content is 12%, the compressive strength of granite mechanism sand concrete is the best, which is 68.3 MPa. The slump of concrete decreases with the increase of stone powder content. The increase of stone powder content suppresses cement hydration to some extent, and increases the amount of unhydration cement and fly ash. When the compressive strength of mechanism sand concrete is optimal, the Ca/Si ratio (CaO/SiO2 mole ratio) of C-S-H gel is the lowest. The stone powder content and mother rock type do not affect the hydration products of mechanism sand concrete.

A large amount of low-level radioactive concrete nuclear waste with contamination and activation will be generated when the nuclear facilities are decommissioned. Glass material has been used to immobilize kinds of radioactive wastes because of its wide incorporation to radioactive elements and excellent chemical durability, compared with traditional cement solidification. In this paper, the simulated structural concrete nuclear waste was treated by high temperature melting. The concrete was vitrified with the glass additive (~26% (mass fraction) SiO2, ~13% (mass fraction) B2O3 and ~6% (mass fraction) Na2O) at 1 300 ℃, and the chemical durability of thus resulted glass waste form meets the disposal requirements for low-level waste form. The volatilization behavior of the simulated nuclides at high temperature and their local structure in the glass were finally discussed. The results can provide the basic information to vitrify the concrete nuclear waste.

In order to promote the high value-added utilization of high calcium fly ash, the geopolymer with excellent mechanical properties was prepared using fly ash as main raw material by water glass alkali excitation. Then, hydrogen peroxide was introduced as foaming agent, sodium dodecyl sulfate (SDS) was used as foaming stabilizer and the foaming process was optimized to prepare porous foaming geopolymer. The pore size distribution of foaming section was analyzed by Image-Pro Plus image software and the microstructure of foaming geopolymer was characterized by XRD, FTIR and SEM-EDS. The results show that under the conditions of liquid-solid ratio of 0.50, alkali equivalent of 10% (mass fraction), water glass modulus of 1.50, H2O2 content of 3% (mass fraction), SDS content of 0.3% (mass fraction) and foaming at 80 ℃ for 4 h, the 28 d compressive strength of specimen after standard curing is 1.78 MPa, and the apparent density is 631 kg/m3. Foaming geopolymer has small pore size and uniform distribution, resulting in low density. The polymerization product is a small amount of C-S-H gel and a large amount of N(C)-A-S-H gel produced by the synergistic reaction of calcium, aluminum and sodium, which ensures the mechanical strength of foaming geopolymer.

For high value-added utilization of carbide slag and sequestration of CO2, spherical vaterite was prepared at atmospheric pressure using carbide slag as raw material and various additives. The effects of additive types, reaction temperature, impurities in carbide slag and reaction system on vaterite in calcium carbonate synthesis were investigated by X-ray diffraction, scanning electron microscope and fourier transform infrared spectroscopy. The results show that glycine and serine have significant effect on the formation of vaterite. The increase of reaction temperature is not conducive to the formation of vaterite. The impurities Al2O3 and SiO2 in carbide slag induce Ca(OH)2 mineralization CO2 system to form calcite. Different reaction systems affect the crystal size of prepared vaterite, and the crystal size prepared by carbide slag-CO2 system is the smallest. In the carbide slag-CO2 reaction system at 15 ℃, monodisperse vaterite type CaCO3 with rough protrusions on the surface can be prepared by adding glycine. The above results provide a simple method for preparing high value-added vaterite from alkaline industrial wastes such as carbide slag, and safely and effectively storing a large amount of CO2 greenhouse gases.

To investigate the freeze-thaw resistance of composite limestone powder-fly ash-slag concrete, rapid freeze-thaw test and mercury compression test were conducted on concrete of three cementitious material systems at four different water to binder ratios. The degradation law of the freeze-thaw resistance was studied in terms of appearance damage, mass loss, relative dynamic elastic modulus and pore structure. The results show that: under the same conditions, the freeze-thaw resistance of concrete can be improved by appropriately reducing the water to binder ratio. Compared with ordinary concrete, the composite cementitious material system composed of mineral admixtures such as limestone powder, slag and fly ash and cement improves the freeze-thaw resistance of concrete. Because the activity of slag is higher than that of fly ash, "20% (mass fraction, the same below) limestone powder+15% fly ash+15% slag" concrete is weaker than "20% limestone powder+30% slag" concrete. The mineral admixture can refine the pore size of concrete and improve the freeze-thaw resistance. Through theoretical analysis and regression of experimental data, the freeze-thaw damage model of composite limestone powder-fly ash-slag concrete with different cementitious material systems was established.

Soft soil has low bearing capacity and poor engineering characteristics, so it can not be directly used as foundation for engineering construction. In addition, China’s industrial waste residue has a huge output and low utilization rate. In order to promote the requirements of high-quality development, this paper uses fly ash as precursor, carbide slag and sodium sulfate as activators to study the solidification mechanism and microstructure development of soft soil. The results show that the optimal mix ratio is 17.3% (mass fraction, the same below) of fly ash, 7.3% of carbide slag and 5.0% of sodium sulfate. The 7 and 28 d unconfined compressive strength of solidified soil under the optimal ratio are 2 474.0 and 3 134.0 kPa, respectively, and the error is small compared with the predicted strength. The response surface method is effective and scientific to optimize the mix ratio. The water stability coefficients of solidified soil at 7 and 28 d are 0.73 and 0.85, respectively, indicating that the solidified soil has good water erosion resistance. The hydration products of 28 d solidified soil are mainly hydrated calcium silicate (C-S-H) and ettringite (AFt), which fill and wrap the internal pores of solidified soil. The microstructure of solidified soil is gradually dense and the mechanical properties are improved.

Alkali-activated cementitious material is a new type of low-carbon material. The pore solution of alkali-activated cementitious materials generally has more alkalinity than cement-based materials, inevitably leading to the different volume deformation caused by alkali-aggregate reaction. Granite was selected as a representative aggregate to prepare alkali-activated metakaolin-slag mortar for exploring the relationship between the alkalinity of pore solution and alkali-aggregate reaction. The deformation behaviors of mortar immersed in the NaOH solution with different concentrations were studied. According to the microstructure analysis, it is shown that the volume shrinkage of alkali-activated cementitious materials can effectively suppress the expansion caused by alkali-aggregate reaction. Under different soaking conditions, the alkali-activated metakaolin-slag mortar exhibits different deformation behaviors. The expansion behavior of alkali-activated metakaolin-slag mortar is caused by the alkali-aggregate reaction products and the transformation from a zeolite-like structure sodium silicaluminate hydrate gel to a zeolite structure gel. Alkali-aggregate reaction would occur when the hydroxyl ion concentration in the pore solution of alkali-activated cementitious materials is greater than 0.209 mol/L.

In order to investigate synergistic cementing effect between binary solid waste, the mechanical properties of the steel slag-red mud-cement based composite mortar were investigated under different ratio conditions, and the hydration characteristics and microscopic morphology of composite mortar were characterized by hydration heat, XRD, TG-DTG, SEM, etc. The study results show that compared with pure cement group, single addition 30% (the following are mass fractions) steel slag inhibits hydration reaction of slurry, and reduces mechanical properties of mortar. On the basis of adding 30% steel slag alone, adding an appropriate amount of red mud can effectively reduce the negative impact of steel slag on the mechanical properties of mortar. The 28 d flexural strength and 28 d compressive strength of composite mortar are the highest when the steel slag is mixed with 15% and the red mud is mixed with 15%, which are 6.8 and 39.8 MPa, respectively. Compared with the group with single addition 30% steel slag, the 28 d flexural strength and 28 d compressive strength increase by 11.5% and 20.6%, respectively, mainly because the red mud not only plays the role of physical filling, but also provides the physical filling for hydration reaction of steel slag. The hydration reaction of steel slag provides a good alkaline environment, which promotes participation of steel slag in the hydration reaction and generates more calcium alumina and hydrated calcium silicate gel to improve the microstructure of mortar.

In order to further improve the utilization rate of steel slag in steel slag concrete, C30 double-doped steel slag concrete was prepared by replacing natural coarse aggregate and fine aggregate in concrete with coarse steel slag and fine steel slag at the same mass ratio, and the effects of coarse and fine steel slag aggregates substitution level on the mechanical properties and durability of double-doped steel slag concrete were studied. The results show that the mechanical properties of double-doped steel slag concrete are generally better than those of ordinary concrete. With the increase of coarse and fine steel slag substitution levels, its mechanical properties are enhanced, its carbonization resistance is first enhanced and then weakened, and its resistance to chloride ion permeation is gradually weakened. In this paper, the relationship between the cubic compressive strength of double-doped steel slag concrete and other mechanical indexes was also studied, and the corresponding conversion formula was given. Considering both the mechanical properties and durability of double-doped steel slag concrete, it is suggested that the replacement rate of coarse and fine steel slag aggregates should not be higher than 40% （mass fraction）.

To study the fatigue resistance of fiber reinforced lightweight aggregate concrete, constant stress cyclic compression tests were conducted to investigate the fatigue stress-strain response. The experiment used 20% (mass fraction) fly ash and 50% (mass fraction) granulated blast furnace slag to partially replace cement, and the experimental variables were single or mixed with different amounts of steel fibers and PVA fibers. The results show that with the increase of number of cycles loading, the number of macroscopic cracks in steel fiber reinforced concrete is more than that in PVA fiber reinforced concrete. The failure modes of specimens are manifested as the rupture of lightweight aggregate and the gradual extraction (steel fibers) or fracture (PVA fibers) of fibers. Steel fiber reinforced concrete has the highest fatigue strain and residual strain, while hybrid fiber concrete has the lowest. At the same stress level, hybrid fiber concrete has the longest fatigue life, while steel fiber concrete has the shortest. The ultimate fatigue damage of steel fiber concrete is higher than that of PVA fiber concrete and hybrid fiber concrete, and the difference gradually decreases with the decrease of maximum stress level.

Ultra-high temperature ceramics (UHTC) plays an important role in the field of thermal protection in aerospace. High quality UHTC powder is important raw material for the preparation of high performance UHTC. In the process of preparing UHTC powder, the powder prepared by precursor-derived method has high purity, small particle size and uniform distribution of component, so it has broad application prospects. According to the synthesis mechanism of precursor, the precursor-derived methods of UHTC were divided into metal alkoxides complex synthesis method, synthesis based on Grignard reaction method and synthesis by introducing branch chains method. The research progress of preparation of UHTC by three methods in recent years was reviewed. The advantages and disadvantages of three methods were analyzed and summarized. The existing problems and future development direction of the UHTC powder prepared by precursor-derived method were pointed out.

Low temperature enamel (LTE) coating is a new type of inorganic coating developed for metal surface corrosion protection. Understanding melting behavior of LTE coating during sintering process assist in the control of sintering technology, and produce a fully covering and smooth coating. Mass and heat changes of LTE coating powder during sintering process were investigated using synchronous thermal analyzer. Glass transition temperature and thermal expansion coefficient of LTE coating cyclinder sample were measured using thermal mechanical analyzer. Under different heating rates, changes of viscosity, height, volume with contact angle of LTE coating cyclinder sample were studied using self-made hot-stage microscope. Results show that with the increase of heating rate, sintering temperature, softening temperature, and spherical temperature of LTE coating cyclinder sample decrease. The viscosity is also reduced, which is benefical for coating leveling, suggesting that the 20 ℃/min heating rate is optimum. Height and contact angle of LTE coating cylinder sample begin to enter plateau at the temperature range of 530~550 ℃, indicating that this temperature range should be chosen as the sintering temperature of LTE coating.

In this paper, magnesium oxide (MgO) and potassium dihydrogen phosphate (KH2PO4) were used as the solid phase components of magnesium phosphate bone cement, and different content of phytic acid modified hydroxyapatite (IP6-HA) powder was introduced to prepare various magnesium phosphate composite bone cement with different magnesium and phosphorus ratio (M∶P). By adjusting the ratio of MgO and KH2PO4 in magnesium phosphate powder and the content of IP6-HA, the mechanical properties and curing time of bone cement were improved, and the curing mechanism of bone cement was studied. The results show that when the ratio of magnesium to phosphorus is 4 and the content of IP6-HA in the solid phase is 5% (mass fraction), the growth effect of struvite crystals (MgKPO4·6H2O) is the best, the curing time is 7.5 min, the compressive strength can reach 49 MPa, and the strength can reach 69.3 MPa after curing for four weeks. The IP6-HA modified magnesium phosphate composite bone cement obtained from the experiment has good mechanical properties and suitable curing time, which has potential biomedical application prospects.

The high surface area mesoporous SiO2 nanospheres （KCC-1） with fibrous and unique pore structure possess high specific surface area and abundant exposed active sites. KCC-1 is capable of effectively dispersing and stabilizing active components on surface, making an excellent carrier for loading active components. Nitrogen-doped porous carbon material was prepared via two-step pyrolysis using melamine with a high N atom content as carbon precursor. At the same time, the special fibrous structure of KCC-1 was utilized to disperse and confine the active component on its surface, and the effect of KCC-1 content on structure and electrochemical performance of porous carbon material was explored. The results indicate that the overall specific capacitance of material increases first and then decreases with the increase of KCC-1 content. When the mass ratio of KCC-1 is 6%, the specific capacitance of material is the highest, reaching 35.88 F·g-1 (at current density of 1 A·g-1), which representes an enhancement of approximately 588.7% compared with the pristine material without KCC-1. After conversion, the specific capacitance of active components at an equal mass can reach a maximum of 190.53 F·g-1. Therefore, this study demonstrates that the confinement effect of KCC-1 can effectively enhance electrochemical performance and utilization efficiency of active components, providing valuable references for its future application in supercapacitors.

The numerical simulation of drying process in ceramic green body was carried out with Fick diffusion model. The influences of hot wind speed, temperature and relative humidity on internal temperature, water content and drying rate of ceramic green body were analyzed within the numerical range of actual drying process parameters. The results show that water loss rate of surface area of green body increases with the increase of hot wind speed, and the wind speed has little effect on water content inside green body. The drying rate inside green body is significantly increases by increasing the temperature, and the maximum drying rate changes by 46.34% when temperature increases from 35 ℃ to 75 ℃. When relative humidity increases from 5% to 85%, the equilibrium water content increases from 0.8% to 5.1% (all are mass fraction), and the increase of relative humidity can improve drying uniformity of green body and ensure the drying quality of green body. The numerical simulation results are consistent with the experimental results. The numerical simulation data provide a theoretical foundation for further research on the heat and mass transfer process in the drying process of ceramic green body and the optimization of the drying curve of ceramic green body.

With the combination of injection molding and gas pressure sintering, ceramic shaped parts with small size and high precision can be prepared in large quantities at low cost. In this paper, low density polyethylene (LDPE) and ethylene-vinyl acetate copolymer (EVA) were used as binders to prepare silicon nitride green bodies under injection temperature of 165 ℃ and injection pressure of 85 MPa. The complete silicon nitride injection molding process route was obtained by thermal degreasing process and sintering kinetics test. The effect of feedstock solid content on green body density, sintering density and Vickers hardness and the non-Newtonian index change of feedstock at 140~160 ℃ were studied. The results show that the optimum solid content of feedstock is 52.42% (volume fraction). The density of silicon nitride injection green body prepared under this condition is 2.10 g/cm3, the sintering density is 3.23 g/cm3, and the Vickers hardness is (15.24±0.34) GPa. The non-Newtonian index of feedstock is smallest at 160 ℃, that is, the rheological of feedstock is the best at this temperature.

In this paper, R2O-RO-Al2O3-B2O3-SiO2 based sealing glass-ceramics with diopside as main crystalline phase was designed and prepared for the sealing of solid oxide fuel cell (SOFC). The effect of Na2O content (0%～10%, mole fraction) on coefficient of thermal expansion (CTE), crystallization and sintering wetting property of sealing glass was analyzed, and the sealing interface between glass and SUS403 stainless steel after high temperature and long time heat treatment was characterized. The results show that Na2O can significantly improve the thermal properties of glass, the prepared glass samples can be obtained as glass-ceramics with main crystalline phase of diopside (CaMgSi2O6) after heat treatment in sealing temperature range. With the increase of Na2O content, the crystal phase content of main crystal phase diopside is different, and coefficient of thermal expansion of glass-ceramics increases from 8.22×10-6 K-1 before crystallization to 11.79×10-6 K-1, which can meet the thermal expansion match of SOFC sealing. When the Na2O content is greater than or equal to 8% (mole fraction), the crystalline phase of high expansion calcium akermanite (Ca2MgSi2O7) is precipitated in glass, which is not conducive to sealing. After sealing 4% (mole fraction) glass sample with SUS403 at high temperature for 100 h at 850 ℃, the sealing interface is dense and firm without air pores. There is a Cr2O3 layer at the interface and a thin layer of diopside which is denser than glass sealing body. The existence of these dense layers is beneficial to limit the diffusion of Na+ from sealing glass to interface.

A new type of heat-resistant borosilicate glass was designed based on waste TFT-LCD glass raw materials. Aiming at the difficulty in clarification of the heat-resistant glass, which leads to a large amount of bubbles in the glass, the effects of four clarifying agents: CeO2, NaCl, Na2SO4 and SnO2 on the clarification quality of the heat-resistant glass were studied by high temperature video research method of glass batch. The experiment observed the clarification process of glass melt through a high-temperature video system. The results show that at the melting temperature of 1 600 ℃, the best clarification effect is achieved when the addition amount of NaCl and Na2SO4 were added as a single clarifying agent at 0.50% (mass fraction) and 0.20% (mass fraction), respectively. The best clarification effect is achieved when the addition amount of clarifying agent combining CeO2 and SnO2 with NaNO3 is 0.40% (mass fraction) CeO2+2.60% (mass fraction) NaNO3 and 0.40% (mass fraction) SnO2+2.40% (mass fraction) NaNO3. The time for the glass melt foam to start falling back is 22, 10, 20 and 28 min, respectively. The initial falling temperatures are 1 110, 1 050, 1 103 and 1 143 ℃, respectively. Under the optimum holding time, the clarification effect is best with 0.50% (mass fraction) NaCl.

In this study, R2O-Bi2O3-B2O3-SiO2 lead-free low-melting point glass was prepared by high temperature melting method and applied to automobile glass enamel. The effect of composition on the structure, thermal properties and acid resistance of glass was studied. The results show that with the increase of Bi2O3/B2O3 and Bi2O3/SiO2, the ［BO3］ and ［BiO3］ triangular structural units gradually decrease, the ［SiO4］ and ［BO4］ tetrahedral structural units gradually increase, and the network structure of glass is enhanced. When the alkali metal oxide content is 15% (mole fraction), the thermal expansion coefficient α25~320 ℃, transition temperature Tg and softening temperature Tf of double alkali glass are smaller than those of single alkali glass, and the acid mass loss rate Dr is lower. When n(Li2O)∶n(Na2O) is 1∶1, the α25~320 ℃ of double alkali glass is 9.35×10-6 ℃-1, the Tg value is reduced to 439.8 ℃, the Tf value is 481.7 ℃, and the Dr value is 0.006 70 g/cm2. Applying it to automotive glass enamel, the sintered enamel has good adhesion, blackness, coverage and gloss.

Based on the characteristics of pearlescent sand with many pores, low bulk density and low thermal conductivity, the influence of additive amount of pearlescent sand on the performance of bauxite castable was studied to improve the thermal insulation performance of permanent lining castable for tundish. The results show that with the increase of additive amount of pearlescent sand, the bulk density of castable decreases and the apparent porosity increases, which are related to the characteristics of pearlescent sand. Meanwhile, with the increase of the additive amount of pearlescent sand, water added of castable increases, and the in-situ pores formed by water evaporating inside castable increases during firing. Due to the decrease of the strength of pearlescent sand after water absorption and the limited bonding between pearlescent sand and the matrix in the castable, the flexural strength and cold compressive strength of castable decrease with the increase of the additive amount of pearlescent sand. Comprehensive analysis show that the optimum additive amount of pearlescent sand is 3% (mass fraction). The thermal conductivity of 3% pearlescent sand bauxite castable at high temperature of 400~800 ℃ is about 30%, smaller than that of conventional bauxite castable, which proves that the addition of pearlescent sand can significantly improve the thermal insulation performance of bauxite castable.

Fused cast Al2O3-ZrO2-SiO2 (AZS) refractory is the key building material of glass furnace. Calcined aluminum oxide powder and ordinary industrial aluminum oxide powder were used as raw materials to prepare fused cast AZS refractories, respectively. The structure and properties of the two fused cast AZS refractories were compared and analyzed by lithofacies analysis, X-ray diffraction analysis, and energy dispersive spectroscopy analysis, etc. The results indicate that fused cast AZS refractory material prepared by ordinary industrial aluminum oxide powder has the incomplete conversion γ-Al2O3, which leads to uneven distribution of Al2O3-ZrO2 eutectic. The alumina phase in the fused cast AZS refractory prepared by calcined alumina oxide powder is α-Al2O3. The fused cast AZS refractory prepared by calcined aluminum oxide has less baddeleyite, more Al2O3-ZrO2 eutectic and more uniform distribution of glass phase. The distribution of crystal structure affects amount of glass phase exudation and corrosion resistance to molten glass. The glass phase exudation of the fused cast AZS refractory prepared by calcined aluminum oxide powder is 0.57 percentage points lower than that of fused cast AZS refractory prepared by ordinary industrial aluminum oxide powder. The corrosion resistance to molten glass of fused cast AZS refractory prepared by calcined aluminum oxide power is 0.15 mm/24 h higher than that of fused cast AZS refractory prepared by ordinary industrial aluminum oxide power.

Developing cheap and efficient catalysts is the key to develop electrolytic water industry. Layered double hydroxides （LDH） exhibit excellent performance in electrocatalytic oxygen evolution reactions, but these catalysts exhibit poor electrochemical performance in hydrogen evolution reactions. Excellent hydrogen evolution performance was achieved by doping Ag element into NiFe-LDH nanosheet arrays. The results show that in 1 mol/L KOH solution, the required overpotential for a current density of 10 mA·cm-2 is only 73 mV, and the Tafel slope is 61.3 mV·dacade-1. At a high current density of 800 mA·cm-2, the overpotential is only 493 mV, which is significantly lower than that of commercial platinum carbon catalysts.After 30 h of stability testing, the electrochemical performance remains above 90%.The improvement in catalytic performance is attributed to the reduction in nanosheet size and increase in specific surface area caused by Ag doping with NiFe-LDH, which effectively enhances hydrogen production kinetics and improves electron transport, thereby optimizing the electrocatalytic hydrogen evolution performance of NiFe-LDH.

Cs3Bi2I9 single crystals were prepared by evaporative crystallization method at the conditions of low temperature and atmospheric pressure, with temperature ranging from 60 ℃ to 90 ℃ and holding time ranging from 18 h to 30 h. The effects of temperature and holding time on the crystal structure and optical properties of Cs3Bi2I9 single crystals were investigated. The Cs3Bi2I9 single crystal film based on flexible substrate was prepared by mechanical exfoliation method and its electrical properties were studied. The results show that, for the best crystallinity target, the optimal parameters for the growth of Cs3Bi2I9 single crystals are the temperature of 60 ℃ and holding time of 26 h. The effects of temperature and holding time on the crystallinity, ultraviolet visible light absorbance, and photoluminescence properties of Cs3Bi2I9 single crystals are consistent. The flexible Cs3Bi2I9 single crystal film has obvious photoelectric properties, and shows excellent stability during work. Cs3Bi2I9 single crystal film has outstanding bending durability. After bending 100 times at the angle of 90°, the performances of Cs3Bi2I9 single crystal film still maintain at 84.4% of the original performances. Lead-free perovskite Cs3Bi2I9 single crystal film has potential application prospects in flexible photoelectric sensor devices.

In this paper, Zn coated silica fiber was prepared online by molten metal method, and the influence of coating temperature on the surface quality and mechanical properties of Zn coated silica fiber was explored. The coating coverage rate was calculated using image processing software. The coating thickness, grain size, and roughness were measured using scanning electron microscopy, polarizing microscopy, and laser confocal microscopy, respectively. It is found that as the coating temperature increases, the coating coverage rate and coating thickness decrease, the solidification time of coating is prolonged, the grain size increases, and the roughness of coating gradually increases. The breaking force was measured by tensile testing machine. The maximum breaking force of Zn coated silica fiber increases by 139% compared with bare fiber.

The Fenton-like reaction is one of the most effective methods for decomposing organic pollutants in water. Designing efficient heterogeneous catalysts is crucial in this industry. The hard template method was used to construct FeCeOx materials with Fe-doped ordered mesoporous structures, and the impregnation method was employed to create multi-metallic active sites after loading Cu and Co as the carrier. Methylene blue could be entirely eliminated in 45 min by using an as-prepared catalyst with strong recycling capacity. After 5 runs, methylene blue degradation could still reach 93.3%. The porous structure of the catalyst is conducive to enhancing methylene blue absorption, exposing more active spots, and the synergistic effects of multi-metals promote electron transport, thus boosting the activation efficiency of H2O2 and the formation of ·OH.

In this work, monolithic zinc oxide/bismuth oxychloride/graphite oxide/polyvinylidene fluoride (ZnO/BiOCl/GO/PVDF) composite membrane was prepared by immersion precipitation phase transition method. The photocatalytic degradation performance of the composite membrane was verified by using methylene blue (MB), rhodamine (RhB) and tetracycline (TC) as target pollutants, and the composite membrane was tested by XRD, SEM and other testing methods. The results show that the thin sheet structure of bismuth oxychloride (BiOCl) provides more active sites, the fold-like structure of graphene oxide (GO) facilitates the adhesion of ZnO, which contributes to the improvement of photocatalytic effect. Meanwhile, ZnO combines with BiOCl to form p-n heterojunction structure, expanding the visible light response range of the composite material. Under the irradiation of visible light, the removal rate of RhB reaches 95.5% at 180 min, and the removal rate of TC reaches more than 93.1% at 140 min, which can achieve the basic removal of pollutants. The degradation rate of MB by the composite membrane still reaches 97.8% after 5 times of recycling. Under the background of “double carbon”, the monolithic ZnO/BiOCl/GO/PVDF composite membrane prepared in this work can be used as an environmentally friendly, stable and economical photocatalyst for the removal of water-soluble pollutants such as MB, and the composite membrane has a broad application prospect in the degradation of water-soluble pollutant wastewater by monolithic catalyst.

Hydroquinone(HQ) was mainly used in the industrial field as a stabilizing agent and antioxygen. The residue of hydroquinone in industrial wastewater was seriously harmful to human body and environment. Therefore, it is of great significance to establish a simple and accurate method for the detection of hydroquinone for food safety and environmental monitoring. In this paper, a nano-zinc oxide-high purity graphite/glass carbon (ZnO-C/GC) composite electrochemical sensor was prepared. The experimental materials were simple and low cost. The structural characteristics, surface characteristics and conductivity of nano-ZnO-C composites material were analyzed by atomic force microscope (AFM), field emission scanning electron microscope (SEM), X-ray diffraction (XRD) and electrochemical AC impedance (EIS). Hydroquinone by cyclic voltammetry (CV) was used to realize the detection of hydroquinone by nano-ZnO-C/GC composite electrochemical sensor. The electrocatalytic mechanism of hydroquinone was explored. The electrochemical sensor has good stability and accuracy for the detection of hydroquinone, a wide linear range, and a detection limit of 1.0 × 10-8 mol/L.

To clarify the progress of application of different grouting materials in airport runway engineering, the commonly used grouting materials were introduced and different kinds of grouting materials were classified, the physical and chemical properties, reaction mechanism and their mechanical properties were analyzed, and their application scenarios in airport runway engineering were summarized. Comprehensive analysis of existing studies show that cement-based grouting materials and organic polymer materials are often used for foundation reinforcement and road surface disease treatment in airport projects. Organic polymer materials have advantages of short setting time and high strength, and single-liquid cement slurry materials are widely used and suitably priced, but their working performance is poor. Due to the reason of air service non-suspend construction, the airport runway grouting project requires slurry with good fluidity, fast hard and early strength, high solidification body strength, and certain economy. The modification of single-liquid cement slurry by adding other materials can effectively improve its various properties, and it is now widely used in airport runway grouting projects.

As greener and carbon-friendly material, geopolymer grouting material has a broad application potential in the field of road grouting and is expected to replace cement grouting material in the future. In order to explore the effects of the kinds and dosages of each composition on the performance of geopolymer grouting materials, three kinds of silica-aluminum sources (fly ash, slag powder and coal gangue powder) were used to prepare road geopolymer grouting materials by different alkali activators. The mix proportion range of road geopolymer grouting materials was optimized by single factor test. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR) were used to analyze the phase composition, micro morphology, energy spectrum and chemical bond composition of road geopolymer grouting materials. The results show that road geopolymer grouting material with the best performance is prepared with fly ash and slag powder as raw materials, KOH and sodium silicate solution as composite alkali activator. The recommended mix proportion range of road geopolymer grouting material is: fly ash and slag powder mass ratio is 4∶6, sodium silicate dosage is 10%~15% (mass fraction), KOH dosage is 5%~11% (mass fraction), water-cement ratio is 0.50~0.65. The fly ash and slag powder are dissolved and regenerated by alkali activation to form amorphous gel products such as C-(A)-S-H, and finally formed SiO4 and AlO4 tetrahedron network structure, accompanied by zeolite like phase, carbonate, calcium hydroxide and other substances. These substances can make geopolymer paste compact and promote its strength growth.

In order to characterize the compressive strength of cement-stabilized macadam with a maximum particle size of 53 mm (CTB-50), the reliability of vertical vibration compression testing method (VVTM) was evaluated, and the growth law of cement-stabilized macadam compressive strength with cement dosage and age was studied. The growth equation and prediction model of compressive strength were established, and the influence of gradation type on compressive strength was analyzed. The results show that the compressive strength of VVTM specimens is highly correlated with the core samples of test section, up to about 91%. The compressive strength increases linearly with the increase of cement dosage. The strength increases rapidly at the initial curing stage and tends to be stable after 60 d. The correlation coefficients of established compressive strength growth equation and prediction model with test results are not less than 0.982 and 0.976, respectively, and the absolute values of predicted value errors are less than 3% and 6%, respectively. The initial and ultimate compressive strength of CTB-50 are about 1.25 times and 1.09 times that of conventional cement-stabilized macadam (CTB-30), respectively. With the same strength control index, CTB-50 can reduce the amount of cement, which is conducive to reducing the project cost and cracks of semi-rigid subgrade.