Heat of hydration test, non-evaporating water content test, X-ray diffraction analysis, scanning electron microscope analysis, mercury intrusion test and compressive strength tests were used to investigate the effect of the Co-Fe-Mg-Al hydrotalcite carbon nanotubes (CoFeMgAl-LDHs/CNTs) composite material on the hydration process, pore structure and strength of hardened cement paste. The results show that CoFeMgAl-LDHs/CNTs composite material significantly improves the hydration degree of cement within 3 d through nucleation, and thereby significantly enhances the compressive strength of the cement paste in the age of 3 d, the effect of improving the strength gradually reduces after 3 d and become unobvious after 7 d. Compare with blank cement paste, the content of gel pore and capillary pore in hardened cement paste increase obviously, while the macro pore decreases. At the same time, bridging effect of composite material optimizes microstructure of cement paste, and increase the stress bearing capacity of weak parts of cement matrix. Therefore, at the same age, the strength of hardened cement paste is increased. Because the change of composite content has no obvious effect on the change of pore size distribution, the change of composite content has little effect on the strength improvement of hardened cement paste at the same age.

C-S-H is the main hydration product of common Portland cement, which plays a very important role in the properties of cement-based materials. However, the hydration products of cement are complex, and it is difficult to separate pure C-S-H from the hydration products and explore its influence on cement-based materials. Therefore, nano C-S-H (NC) particles were prepared by the double decomposition method in this paper and mixed into the slag powder-cement system. The influence of NC on the hydration of slag powder-cement system was investigated by means of non-contact electrical resistivity measurement, XRD, DSC-TG, SEM, and MIP. Results show that in the range of 1% to 4% (by mass) dosage, the addition of NC shortens the setting time of matrix, and provides more nucleation sites for cement hydration, accelerates the formation and precipitation of hydration products. It also promotes the bond between the hydration products, thus reducing the porosity and increasing the early strength and resistivity of cement matrix composites.

According to the control problem of loose and fractured roadway, there are many defects about ordinary cement grouting, and cement particles can not be injected into pores or fractures with a radius of less than 0.2 mm. The samples were made by mixture of carbon fiber, polymer and superfine cement, and the best proportion of grouting material was determined by uniaxial compression test and Brazilian splitting test. The test results show that the performance of cement mortar test block is the best when the content of carbon fiber is 10% (mass fraction) of cement content. The microstructure composition of the sample fragment was determined by electron microscope scanning (SEM). Combined with the Ohama model and Konietzko model of polymer film formation, the microstructure formation process and carbon fiber failure mode were analyzed, and the microscopic reinforcement mechanism of carbon fiber reinforced polymer cement grouting material was studied. This research provides technical support for reducing the maintenance cost of deep loose and fractured roadway and realizing the sustainable development of deep mining.

In order to investigate the effect of mineral admixtures on modified magnesium oxysulfate cement and its mechanism, different amounts of fly ash and mineral powder were blended into the modified magnesium oxysulfate cement, and the mechanical properties, water resistance and acid resistance were studied. The composition and microstructure of the material phase were characterized and analyzed by X-ray diffraction and scanning electron microscopy, respectively. The results show that the incorporation of fly ash will increase the 3 d strength of modified magnesium oxysulfate cement, and the later strength decreases, its 28 d compressive strength loses 14.7% compared with the reference group when the fly ash dosage is more than 20% (mass fraction). The incorporation of mineral powder has little effect on the preliminary strength of modified magnesium oxysulfate cement, and makes the later strength decrease, and the 28 d strength loss rate of the cement is as high as 17.3% when the mineral powder dosage is 30% to 40% (mass fraction). Both fly ash and mineral powder are able to enhance the water resistance and sulfuric acid corrosion resistance of modified magnesium oxysulfate cement, where the corrosion resistance of cement is enhanced with the increase of fly ash admixture, and the best dosage of mineral powder with the best sulfuric acid corrosion resistance is 20%.

The effects of magnesia and calcium sulphoaluminate expansive agent on hydration products and microstructure of engineered cementitious composites were studied. The results show that the two expansive agents decrease the fluidity and mechanical properties. The addition of magnesia expansion agent makes a large amount of magnesium-rich calcium-silicate in the material system, while the addition of calcium sulfoaluminate expansion agent increases the content of ettringite in the material system. The two hydration products refine the pore structure of the material and improve the impermeability of the samples. The pore diameter of the sample dope with 5% (mass fraction) calcium sulfoaluminate expansion agent is smaller than that with magnesia expansive agent, and the structure of sample with calcium sulfoaluminate expansion agent is more stable.

Five kinds of lightweight aggregate (LWA) cement mortars with different volume replacement ratios were prepared by the equal volume replacement method. The influence of LWA on the mechanical properties and capillary water absorption of cement mortar was tested using compressive, flexural strength test and weighing method. Based on the low-field nuclear magnetic resonance (LF-NMR) and scanning electron microscopy (SEM), the microstructure characteristics of LWA were analyzed. The results show that the weak mechanical strength of LWA affects the overall mechanical properties of cement mortar. As the replacement ratio of LWA increases, the compressive strength of the mortar decreases correspondingly. The capillary water absorption decreases with the increase of the replacement ratio and the age of LWA mortar. LF-NMR test data shows that the volume fraction of small pores decreases with the increase in the replacement ratio of LWA, and the volume fraction of medium and large pores is positively correlated with the replacement ratio. As the age increases, the amplitude of the signal amplitude representing the small pores decreases. The analysis of the interface transition zone (ITZ) of LWA mortar with SEM images indicates that the structure of the LWA mortar ITZ is relatively dense. At the same time, because the hydration product blockes the microporous surface of LWA, the impermeable boundary and internal closed pores are formed. The mortar mixed with LWA exhibits the characteristics of high porosity and low permeability during the capillary water absorption process.

In order to improve the early-strength and frost resistance of concrete in severe cold environment, air entraining agents are often applied in combination with the early-strength and antifreeze agents， while the properties and mechanism of foaming power and foam stabilization are still not clear when they are used together. In this paper, three kinds of air entraining agents were selected: sodium dodecyl benzene sulfonate (SDBS), trimethyl hexyl ammonium bromide (CTAB) and fatty alcohol polyoxyethylene ether (AEO-9). The effects of Na2SO4, NaNO2 and ethylene glycol on surface activity, foam performance and air content of air entraining concrete were systematically compared. The results show that the addition of Na2SO4 and NaNO2 reduces the critical micelle concentration (cm) of the solution containing air entraining agents. For SDBS and AEO-9, the cm is not affected by ethylene glycol, which increases the cm of CTAB. The variation of foam height of air entraining agents solution conforms to the exponential attenuation model. In addition, Na2SO4, NaNO2 and ethylene glycol decrease the foam stability for SDBS and CTAB, but increase the foam stability of AEO-9 to a certain extent. Based on the concrete experiment, some correlation is observed between air content of concrete and the foam performance of air entraining agents solution while there are still obvious differences.

Peat has the characteristics of high water content, high organic matter content, large void ratio and low shear strength. Chemical solidification can be used to improve the bearing capacity and deformation resistance of the soft ground. By conducting one-dimensional consolidation test, effects of water content, organic content, pH value， cement content and sand particle size on compression modulus and consolidation coefficient of cement solidified peat were systematically investigated. The results show that the amount of hydration reaction induced gel increases with the increase of cement content and curing age, resulting in an increase in compression modulus of solidified peat. By decreasing water content from 600% to 300%, the compression modulus of solidified peat increases by 3.5 times. The compression modulus of solidified peat decreases by 50% as organic content of peat increase from 40% to 80% (mass fraction). Moreover, the compression modulus of solidified peat decreases by 158% as pH value decrease from 70 to 35. Based on compression modulus and consolidation coefficient of solidified peat, water and cement contents have the greatest influence on solidified peat, followed by organic content and pH value. The modulus of solidified peat can be increased by adding quartz sand, and the smaller the size of sand particle, the greater the compression modulus.

The impact resistance and failure modes were assessed by impacting composite wall panels with a 2 040 g steel ball from heights of 1.0 m, 1.5 m, 2.0 m and 2.5 m, respectively. While the test was being conducted, an ultra-high-speed camera recording 2 000 frames per second was used to provide footage. The impact resistance of lightweight steel-framed foamed concrete composite wall panels of different structures was evaluated. The results show that reinforcement methods such as steel wire mesh, fiber and fiberglass mesh enhance the impact resistance of lightweight steel-framed foamed concrete composite wall panels. The cracks appear in the three of composite wall panels when the impact height is 2.0 m, 20 m and 25 m, and the energy absorption ratio is 9780%, 9670% and 9657%， respectively. The lightweight steel-framed foamed concrete composite wall panels reinforced with fiberglass mesh provide better impact resistance. The lightweight steel-framed foamed concrete composite wall panels exhibit different levels of impact resistance according to their position on the surface. Compared to lightweight steel-framed area, the non-lightweight steel-framed area and the calcium silicate board have lower energy absorption ratios, which have better impact resistance.

In order to study the dynamic mechanical properties of foamed concrete at low temperature, a 100 mm aluminum split Hopkinson pressure bar (SHPB) equipment was used to carry out impact compression tests on foamed concrete specimens at different temperatures. The stress-strain curves, energy parameters and crushing forms of foamed concrete at different temperatures and strain rates were obtained. The results show that when the strain rate is below 62.59 s-1, the stress-strain curves of foamed concrete are divided into linear elastic stage, yield stage and failure stage. When the strain rate exceeds 62.59 s-1, the stress-strain curves are divided into linear elastic stage, yield stage, local instability stage, stress plateau stage and failure stage. At room temperature, 0 ℃, -10 ℃, -20 ℃ and -30 ℃, the dynamic compressive strength and absorption energy of foamed concrete show significant strain rate effect before the corresponding cut-off point of strain rate, but the strain rate effect is not obvious after the cut-off point. The dynamic peak compressive strength and absorption energy of foamed concrete increase with the decrease of temperature, but the peak strain decreases with the decrease of temperature. The lumpiness of foamed concrete after impact becomes larger with the decrease of temperature. In the dynamic load resistance design of foamed concrete under low temperature environment, the influence of temperature effect is given priority to the peak compressive strength and absorption energy of foamed concrete, while the strain rate effect is given priority to the peak strain of foamed concrete.

To study the influences of coarse polypropylene fiber content and length-diameter ratio on the workability and mechanical properties of pumped concrete, the tests of slump, expansion, compressive strength and splitting tensile strength of coarse polypropylene fiber reinforced concrete (CPFRC) were carried out with base concrete adding coarse polypropylene fiber with different dosages and length-diameter ratios. In addition, the enhancement effects of the fiber content and length-diameter ratio were quantified on the basis of the gray correlation theory. The research results show that the content of coarse polypropylene fiber and the length-diameter ratio have significant effects on slump, expansion, early compressive strength and splitting tensile strength of pumped concrete. Compared with the base concrete, when the coarse polypropylene fiber content is 3 kg/m3, CPFRC has the best workability and the compressive strength enhancement effect. And the slump and the expansion degree reduce by 1.41% and 15.76%, while the compressive strength of 7 d, 14 d and 28 d increase by 20.42%, 14.96% and 11.49%, respectively. When the content of coarse polypropylene fiber is 6 kg/m3, the splitting tensile strength enhancement effect of concrete is the most obvious, and the splitting tensile strength of 7 d, 14 d and 28 d increase by 27.46%， 13.61% and 15.92%, respectively. The workability and mechanical properties of CPFRC are optimized when the content of coarse polypropylene fiber is 3 kg/m3 and length-diameter ratio reaches 47.5, and the total correlation of the workability and the mechanical properties reaches 0.849.

The dispersion degree of glass fiber in concrete is related to the mechanical properties and impermeability of glass fiber concrete. In this paper, the effects of polymer type hyperdispersant (B193), polyether modified polymer (S-3101B) and sodium carboxymethyl cellulose (CMC) on the microstructure, surface condition, compressive strength, splitting tensile strength and impermeability of glass fiber concrete were investigated. The results show that the three dispersants improve the dispersivity of glass fiber in glass fiber concrete, but the dispersant S-3101B mixed into the concrete causes many pores in the concrete, which reduces the mechanical properties and impermeability of glass fiber concrete. When the dispersant B193 dosage is 0.5% (mass fraction relative to the gel material, the same below), the best impermeability of glass fiber concrete specimens is achieved, and the seepage height is reduced by 16.6%. When the dosage of dispersant CMC is 0.5%, the seepage height is reduced by 7.1%. The relationship curves between seepage height and dispersant dosage of glass fiber concrete mixed with three dispersants are established for engineering design reference.

This paper intended to prepare high-strength pipe concrete using autoclaved curing, while the concrete with standard curing was used as control sample. The influences of the stone powder replacement rate (granite stone powder/(granite stone powder+ground） sand, by mass), and the stone powder content (granite stone powder/(granite stone powder+cement), by mass) without adding ground sand on the strength of the pipe high-strength concrete were conducted, respectively. The types and morphological characteristics of hydration products of pipe high-strength concrete with granite powder were investigated by XRD and ESEM. The results show that under autoclaved curing, the concrete strength increases first, and then decreases with the increase of stone powder replacement rate and stone powder content. The strengths of the concretes are highest when the stone powder replacement rate is 25% and the stone powder content is 20%, respectively. The SiO2 in the granite powder has a pozzolanic reaction with Ca(OH)2 (cement hydration product) and produce tobermorite under autoclaved condition, and consequently the concrete become more compact. Therefore, the strength of concrete under autoclave curing at 3 d is higher than that of the concrete under standard curing at 28 d in the same mix ratio.

In order to quickly obtain and evaluate the comprehensive performance of concrete, a prediction model of the comprehensive performance of concrete was established based on the relevance vector machine (RVM), in which six main factors affecting the comprehensive performance of concrete were selected as input data and the comprehensive performances (28 d strength, slump extension and apparent density) of concrete were selected as the output data. Then the model was used to predict 5 groups of predicting samples through fitting traning of 14 groups of learning samples. The results show that under the same sample conditions, compared with BP neural network model, RVM model has higher prediction accuracy and less discreteness. Compared with the actual value, the average relative error of concrete comprehensive performance index predicted by RVM model is obviously smaller than that predicted by BP neural network model, which further verifies the reliability of RVM model to predict the comprehensive performance of concrete, and has good promotion value.

In order to solve the problem of heat loss caused by wall in the existing building energy consumption, a kind of dark ribbed sandwich precast composite lightweight insulation wall panel was proposed in this paper, and the thermal performance of this new type of wall panel was studied. First, the thermal parameters of lightweight aggregate concrete and polystyrene granular concrete were tested respectively, and the effects of different thickness combinations of inner and outer blades and core layers, built-in steel mesh and plane truss on the thermal performance of composite wall panels were studied. Then the experimental results are compared with the theoretical analysis results to verify the reliability of the theoretical analysis model, and provide fundamental research support for the thermal design of composite insulation wall panel. Compare with the conventional precast concrete wallboard, the new composite wallboard shows good thermal performance.

Experimental investigation was conducted using concrete specimens to assess the effectiveness of polyurethane (PU) coating in enhancing the mechanical response of concrete specimens under static and impact loads. Three point bending tests were carried out at strain rates of 0.000 3 s-1 and 0.065 s-1 to simulate static and impact loads. The results show that the application of PU coating (on the front or reverse of concrete specimens) has a positive effect on improving the ductility of concrete structure. The maximum strain and cumulative strain energy increase linearly with the increase of PU coating thickness. The method of reverse coating is more efficient in strengthening concrete structure under static load, and the method of front coating enhances the impact resistance of concrete structure. The strengthening ability is effectively improved by the increase of coating thickness. PU coating does not debond during the ultimate failure of test specimens, which implies that the material has good adhesion characteristics and effectively reduces the crushing effect of specimens.

Natural clay minerals are rich in resources, low in cost, abundant in pore structure and stable chemical properties, which are excellent solid adsorbent matrix materials for emission reduction and carbon cycling. The structure characteristics clay minerals for preparation of CO2 solid adsorbents are summarized. Recent development on clay mineral-based CO2 adsorbents with kaolinite, halloysite, montmorillonite, attapulgite, sepiolite and vermiculite are reviewed. The application in industrial flue gas capture and biogas upgrading are introduced. It is indicated that preparing clay mineral-based CO2 adsorbents with high CO2 uptakes, excellent CO2 selectivity, large adsorption temperature range, suitable for industrial application are a technical challenge for the future development.

Kaolinite is the product of natural alteration of feldspar and other silicate minerals. It is a kind of aluminosilicate mineral without water content. Its layered crystal structure makes it have excellent physical and chemical properties and it is wide used. Molecular simulation technology is a scientific research method which studies the properties of materials at the micro level and plays an important role in the research of materials science. This paper summarized the basic principle of molecular simulation technology and the application progress of this technology in the development and research of kaolinite in recent years, mainly including the physical and chemical properties of kaolinite, the influence of doping modification of kaolinite on physical and chemical properties, the law of ion/molecular adsorption of kaolinite, and some application examples of kaolinite in the field of mineral development. According to the characteristics and practical needs of kaolinite, the adsorption characteristics of kaolinite, the influence of kaolinite modified development on adsorption characteristics, and the application of theoretical guidance in mineral development were explored.

Alkali-activated slag cement is an excellent green cementitious material, which is made of partial or total substitution of slag for cement. Under the action of alkali activator, slag hydration produces activity. Alkali-activated slag cement has different hydration mechanisms from ordinary Portland cement under the action of activator because of vitreous phase separation structure of slag, leading to unique mechanical and dry shrinkage characteristics. The composition and structure of slag were introduced in the article, the hydration mechanism of alkali-activated slag cement under the action of sodium hydroxide and sodium silicate respectively was summarized, its basic mechanical properties and dry shrinkage characteristics were discussed, and common methods of fiber shrinkage reduction were listed, which provide a basis for its application and promotion in engineering practice. The shortcomings of existing studies were summarized, and suggestions for future development were given.

In order to study the mechanical properties of stabilized peaty soil, a series of stabilization tests were carried out with machine-made sand as filling material, cement and phosphogypsum as cementing material. Based on the unconfined compressive stength test and uniaxial cyclic loading and unloading test, the stabilized effect of peaty soil was discussed under the different content of cement and phosphogypsum. According to the damage theory and the strain equivalence hypothesis, an elasto-plastic damage model of stabilized peaty soil was established under uniaxial compression. The results show that the compressive strength of stabilized peaty soil increases with the increase of cement content, and the strength growth rate increases first and then decreases with the increase of phosphogypsum content. The stress-strain hysteretic curve of stabilized peaty soil presents a crescent shape with unclosed bottom, and the unclosed areas of hysteretic curve at the beginning of plasticity and near failure stages are larger than that of other cycles, which indicates that more energy loss occurs in these two stages. Finally, considering the effects of cement content and phosphogypsum content, the parameters of the elasto-plastic damage constitutive model of stabilized peaty soil are obtained by curve fitting method according to the test results.

The existence of metallic aluminum in the radioactive incineration ash results in the expansion and deterioration of cement waste forms, due to the reaction of metallic aluminum with high alkali pore solution to produce hydrogen gas in hardened Portland cement or alkali-activated cementitious materials. In this study, low alkalinity cement-based materials were prepared by Portland cement, silica fume and fly ash as the main raw materials, aiming to overcome this problem. Zeolite, polycarboxylate superplasticizer, diutan gum and polyaluminum sulfate were used as well to modify the properties. According to the results, 28 d compressive strength of over 16.6 MPa is achieved by low alkalinity cement-based materials waste forms with 30% (in mass) simulated radioactive incineration ash. The freeze-thaw resistance, immersion resistance and impact resistance meet the requirements of GB 14569.1—2011 specifications. The leaching rate of Ce3+ on the 42 d is 4.41×10-9 cm/d, and the cumulative leaching fraction is 3.4×10-7 cm. The relatively lower pH value of pore solution in the early age and high Ca concentration in pore solution hinders the reaction between the metallic Al and pore solution. At later age, no reaction between metallic Al and pore solution because the pH value of pore solution is below 11.75.

Through splitting strength tests, unconfined compressive strength tests and flexural-tensile strength tests, the enhancement effect of basalt chopped fiber on mechanical properties of cement stabilized porous basalt macadam was studied. The splitting test of mixture with age of 7 d shows that the basalt chopped fiber significantly improves the splitting strength of cement stabilized porous basalt macadam, and the enhancement effect of fiber with the length of 18 mm is better than the fiber with the length of 12 mm and 24 mm on splitting strength of mixture. As for cement stabilized porous basalt macadam with 18 mm basalt fiber, the splitting strength, unconfined compressive strength and flexural-tensile strength increase first and then decrease with the increase of the fiber content. When the fiber content is 0.10% (mass fraction), the fiber has the best enhancement effect on the mechanical properties of mixture. Adding the basalt chopped fiber increases the 7 d unconfined compressive strength, splitting strength and flexural-tensile strength of mixture by 0.7% to 5.4%, 11.4% to 34.3% and 6.9% to 20.4%, respectively. With the increase of curing age, the mechanical properties of mixture are continuously improved. The 90 d unconfined compressive strength, splitting strength and flexural-tensile strength of mixture are 832 MPa, 103 MPa and 372 MPa, respectively. The results show that the road performance of cement stabilized porous basalt macadam is improved by adding basalt chopped fiber.

Backfilling mining is an important way to achieve safe and green mining in mines. It requires a wide origin of source of backfilling materials, low cost, and must meet the requirements of the backfilling process. In order to explore the influence of loess content on the fluidity and mechanical properties of paste backfilling materials, the parameters of yield stress and compressive strength of paste backfilling materials under different types of fly ash and different loess content were determined through laboratory experiments. The results show that the backfilling body made of loess instead of fly ash is convenient and low cost, and large particles are well wrapped in loess particle, which reduces the wear on the inner wall of pipeline during particle transportation and improves the fluidity of the slurry. With the increase of loess content, the compressive strength of backfilling body gradually increases, but when the mass fraction of loess exceeds 12.5%, the loess fine particle hinders the bonding between cement and other materials, resulting in a decrease in compressive strength. When the mass ratio of loess to fly ash is 2∶8, 3∶7, and the curing period is 28 d, the backfilling material not only meets the requirements of backfilling process, but also reduces the backfilling cost to the maximum extent.

In order to improve the comprehensive utilization rate of fly ash and reduce the cost of raw materials, ultra-high performance concrete (UHPC) was prepared by the mass fraction of raw fly ash without grinding and sorting instead of silica fume. The effects of different amounts of raw fly ash on the mechanical properties and microstructure of UHPC were studied. The results show that the particle size distribution of cementitious material in UHPC is gradient, and good micro-grading can be formed by the addition of raw fly ash. The fluidity of fresh concrete increases and the distribution of steel fiber in UHPC matrix is affected. When the raw fly ash content does not exceed 30%, the flexural strength of UHPC increases in varying degrees with the increase of raw fly ash content. Compared with the blank sample without fly ash, the flexural strength of UHPC with 30% raw fly ash increases by 34%. In the range of 10% to 40% content of raw fly ash, due to the slow hydration of raw fly ash, the UHPC compressive strength decreases with the increase of replacement content of raw fly ash. The pore structure analysis shows that the average pore size and total pore volume of UHPC decrease with the addition of raw fly ash, and the matrix is more dense. When the raw fly ash content is 30%, SEM images show that the steel fiber is closely combined with UHPC matrix and the interfacial adhesion is enhanced.

Phosphorus slag concrete without plastic steel fiber was used as the reference. Taking plastic steel fiber as the research object, four-point bending tests were carried out on plastic steel fiber phosphorus slag concrete with fiber length of 30 mm, 40 mm, 55 mm and fiber content of 3 kg/m3, 6 kg/m3 and 9 kg/m3 to study the influences of different fiber length and fiber content on the bending properties of phosphorus slag concrete. The results show that the bending strength of phosphorus slag concrete increases with the increase of the length and content of plastic steel fiber. When the length of plastic steel fiber is 55 mm and the content of plastic steel fiber is 3 kg/m3, the bending strength of phosphorus slag concrete is the best, and the bending strength is 56% higher than that of the reference group. With the increase of length and content of plastic steel fiber, the bending toughness index and bending toughness of phosphorus slag concrete increase continuously. When the length of plastic steel fiber is 55 mm and the content of plastic steel fiber is 9 kg/m3, the bending toughness index I20 is 9.8 times higher than that of the reference group.

In order to utilize glass powder as a partial replacement of slag to prepare the alkali-activated slag cementitious material, the effect of glass powder content (10%, 20%, 30%, 40%, mass fraction) on the properties of alkali-activated slag-glass powder based (AASG) foamed concrete was studied. The fluidity, compressive strength, drying shrinkage, water absorption, softening coefficient and frost resistance of AASG foamed concrete were tested, and the mechanism was analyzed by scanning electron microscope and X-ray diffractometer. The results show that the use of 10% to 40% glass powder increases the fluidity of AASG foamed concrete by 5.0% to 25.6%. The compressive strength increases first and then decreases with the increase of glass powder content. The 7 d and 28 d compressive strength reach the peak when 20% glass powder is used, increasing by 15.0% and 23.8% compared with the control group respectively. When 20% glass powder is used, the drying shrinkage, water absorption, softening coefficient and frost resistance of AASG foamed concrete are the best. SEM analysis shows that glass powder contributes to the optimization of pore structure and compactness of microstructure. XRD analysis indicates that the main hydration products are C-(N-)A-S-H and hydrotalcite. Therefore, the inclusion of glass powder in AASG foamed concrete as a replacement for slag is feasible, which provides theoretical support for its application in backfill engineering and solid waste utilization.

This study is aimed to solve the problems of weak mechanical properties and low degree of slag reaction when weak single alkali-activated slag cementitious material (AASM), and to alleviate the operational hazards of AASM. Therefore, a combined activator of Na2SiO3/Na2CO3 was used to investigate its influence on the setting time, compressive strength, hydration products and autogenous shrinkage of AASM. Moreover, the environmental benefit of AASM was assessed. The experimental results show that the retarding effect is significant and the compressive strength is reduced with the increase of Na2CO3 alkali dosage, whereas the reduction rate of compressive strength is slightly decreased as the hydration time increased. More types of hydration products are produced by adding Na2CO3. The amount of C-(A)-S-H increased first follow by a decrease with the increase of Na2CO3 alkali dosage, thus explaining the changes in the autogenous shrinkage. Furthermore, based on the CO2 emission index, the combined Na2SiO3/Na2CO3 activated slag is produced in a cleaner manner with greater environmental benefit, compare to the Na2SiO3 activated slag.

Al2O3 ceramics were metallized by the activated Mo-Mn method and the active metal brazing (AMB) process. The interfacial microstructure, formation mechanism of new phases and microstructure evolution of the brazed joints were investigated, and the mechanical properties and the He leakage rate of Al2O3/Cu specimen were tested. The results show that for activated Mo-Mn method, the formation of cubic phase MnAl2O4 is due to the migration of the glass phase at the brazing interface, which can improve the strength of the joint. During the AMB process, the active element Ti and Al2O3 form TiO and Cu3Ti3O layers, with a thickness of 0.64 μm and 1.03 μm, respectively.The difference of coefficient of thermal expansion (CTE) between layers provides good thermoelastic compatibility and reduces residual stress. The bonding strength of samples prepared by the activated Mo-Mn method ((60.2±7.7) MPa) is higher than that of samples prepared by the AMB process ((43.1±6.9) MPa) while the He leakage rates are similar (both around 2.3×10-11 Pa·m3·s-1).

In order to reveal the tensile damage evolution and failure mechanism of plain weave Cf/SiC composites, the X-ray CT in-situ tensile test was carried out to obtain the three-dimensional reconstructed image of the material. The deep learning based image segmentation method was used to accurately identify the tensile crack and realize its three-dimensional visualization. The damage evolution and failure mechanism of plain weave Cf/SiC composites were analyzed, and the damage was quantitatively characterized based on the three-dimensional visualization results. The results show that the tensile mechanical behavior of plain weave Cf/SiC composites is nonlinear, and damages such as matrix cracking, interface debonding, fiber fracture, and fiber pull-out occur during the tensile process. The initial defects are easy to cause material damage, and the higher the porosity, the more cracks there are. The matrix crack outside the fiber tow can extend to the inside of the fiber tow and the crack deflection occurs. The deep learning based intelligence image segmentation method provides an effective analysis method to quantitatively evaluate the damage evolution and failure mechanism of ceramic matrix composites.

Graphite with/without silicon infiltration were oxidized at temperatures of 500 ℃, 700 ℃, 900 ℃ and 1 100 ℃, respectively, and the influence of silicon infiltration on the oxidation behavior of isostatic graphite was studied. SEM was adopted to characterize the surface and interior morphology. The pore structure of graphite was characterized by mercury intrusion porosimetry, and the mechanical properties of samples were measured. Results show that there is no obvious oxidative mass loss of samples at the temperature of 500 ℃. At the temperature of 700 ℃，the mass loss of graphite increases with the oxidation time, while no obvious mass loss is detected for the graphite with silicon infiltration. Moreover, the graphite with silicon infiltration maintains the high strength after oxidized at 700 ℃, but the strength of graphite without silicon infiltration significantly decreases and the bulk graphite even becomes powders. Therefore, the silicon infiltration can significantly increase the strength of graphite while improving its oxidation resistance.

SiC ceramics are prone to edge chipping during grinding. Real-time coating the grinding layer of SiC ceramics with a toughening agent is a new method to control the edge chipping. The toughening agent used in this research was prepared with E51 bisphenol A epoxy resin, anhydrous ethanol, 651 low relative molecular weight polyamide resin, and 1,8-diazabicycloundec-7-ene (DBU) as its main ingredients. By measuring the control angle, wetting depth, and curing time of the toughening agent on the surface of SiC ceramics, the effects of the concentration of the toughening agent ingredients and surface roughness of ceramics on the wetting performance and curing rate of toughening agent were explored, and a toughening agent with good wetting performance and rapid curing rate was obtained. The results show that the optimal mass ratio of the toughening agents m(E51 bisphenol A epoxy resin)∶m(anhydrous ethanol)∶m(651 low relative molecular weight polyamide resin)∶m(DBU) is 1∶0.9∶0.5∶0.02. Under this configuration, the toughening agent penetrates the SiC ceramics surface to a depth of about 40 μm within 160 s, which reduces the surface hardness of the SiC ceramics by about 25%. The wetting performance of the toughening agent increases with the increase of the amount of solvent or the increase of the surface roughness of SiC ceramics, which is found to be almost not affected by the amount of the accelerator. In addition, the curing rate of the toughening agent decreases with the increase of the amount of solvent, and increases with the increase of the amount of accelerator. However, when the amount of accelerator reaches saturation, the curing rate will no longer increase.

Submicron alumina powder (SAP) was added into the green bodies of the architectural ceramic plates by preparation process of building ceramic plate. The effects of SAP on appearance, sintering properties and mechanical property of the ceramic plates were investigated. The results show that SAP is well dispersed in the ceramic bodies and improves the whiteness of ceramic plates effectively. The samples with the dosage of SAP below 15% (mass fraction) have a low water absorption of less than 0.1% and an increasing flexural strength. When SAP dosage is 15% （mass fraction）, the flexural strength of the sample reaches 96 MPa, which is 30% higher than that of the sample without alumina. The further increase in the dosage of SAP results in higher water absorption and lower flexural strength. In the low-quality raw materials with low whiteness, the whiteness and strength of the products can is greatly improved by adding submicron alumina powder, which can not only reduce the consumption of high-quality resources, but also better meet the requirements of decorative effect and mechanical properties of ceramic plates.

Hollow glass microspheres have been widely studied for their low density, high strength and high temperature resistance. Hollow structure of quartz glass microspheres (HSQGM) were prepared by spray granulation method combined with powder method, with the addition of foaming agent and radio frequency plasma as heat source. The effects of SiC, CaCO3 and CaSO4 foaming agents on the preparation of HSQGM were investigated. The results show that the foaming agent and silica are uniformly mixed to form coarse particles by spray granulation method, and then HSQGM are obtained by high temperature sintering of coarse powder by radio frequency plasma equipment. Among them, the effects of CaSO4 and CaCO3 are poor, and the generated gas are difficult to keep inside the glass microspheres to form hollow bubbles, while the effect of SiC is the best, which generates gas inside the glass microspheres in the process of radio frequency plasma sintering and is wrapped by liquid glass to form hollow structures. The average true density of the obtained glass microspheres is 1.799 5 g/cm3. In addition, Feilihua bulk loose quartz is selected as raw material for SiO2 and the HSQGM with an average true density of 0.72 g/cm3 are obtained when the mass ratio of SiO2, SiC and H2O is 100∶3∶300.

Alkali-aluminosilicate glasses with different (Al2O3+P2O5) concentrations were prepared by the melting-quenching method, and their structural characteristics and crystallization behavior were studied by Raman spectroscopy, X-ray diffraction spectroscopy, and scanning electron microscopy. It is found that as the concentration of (Al2O3+P2O5) decreases, the concentration of Na2O increases, resulting in the glass transition temperature decreases from 685 ℃ to 622 ℃. When the (Al2O3+P2O5) concentration decreases to 22% (mole fraction), a crystallization peak appears and the onset crystallization temperature gradually decreases. The intensity of the Raman vibration band corresponding to Q4P becomes lower and gradually shifts towards low frequency, indicating that the Na2O as a network modifier gradually depolymerizes the structure of silicate glass and enhances the crystallization ability of the glass. The results show that there is a crystalline transformation after heat treatment when the concentration of (Al2O3+P2O5) is 22% (mole fraction). The main precipitation crystals are NaAlSiO4 nepheline at 700 ℃ for 2 h while it transforms to Na6.8Al6.3Si9.7O32 nepheline crystals at 900 ℃ for 2 h. When the concentration of (Al2O3+P2O5) is 21% and 20% (mole fraction), Na3PO4 and Na6.8Al6.3Si9.7O32 crystals are precipitated after heat treatment. After heat treatment, phosphorus-rich phase and Na3PO4 crystals with poor acid corrosion resistance are precipitated, resulting in poor chemical stability.

Hydroxyapatite (HAP) is a typical biomaterial, and has been widely used in the bone surgery and dental restoration. Owing to its large specific surface area and high absorbability, HAP has also been used in drug delivery and wastewater treatment. Due to its good electromagnetic property, easy recyclability, and distinct magneto thermoelectric effect, magnetic nanoparticles also gain more attention. To take both advantages, the combination of magnetic materials and HAP has become an important research direction in recent years. Although the preparation of hydroxyapatite composite materials in the past was reported, most of them only focused on the compositing materials and lacked the systematic summary on the synthesis methods. Based on the two ways of introducing magnetism into hydroxyapatite, doping and coating, the classical preparation methods, advantages and disadvantages of magnetic hydroxyapatite as well as the related applications were reviewed. The key problems of further research and future trends were discussed, in order to provide reference for the in-depth research and development of magnetic hydroxyapatite.

The presence of Cd2+ in water endangers human health, and the removal of Cd2+ pollution is a problem that needs to be solved. Wood vinegar modified hydroxyapatite (WV-HAP) was prepared by water bath stirring with hydroxyapatite (HAP) and low cost wood vinegar (WV), and it was used to remove Cd2+ from solution. WV-HAP was characterized by XRD, FT-IR, SEM and BET. The effects of initial pH, initial ion concentration, contact time and temperature on the adsorption characteristics of WV-HAP were investigated through adsorption experiments. The results show that the equilibrium adsorption capacity of WV-HAP is 46.43 mg/g under the conditions of adsorbent dosage of 2 g/L, temperature 298 K, initial concentration of Cd2+100 mg/L, pH=5 and adsorption time 4 h. The adsorption process of Cd2+ by WV-HAP conform to Langmuir isothermal adsorption model and quasi-second-order kinetic model. Thermodynamic study shows that the adsorption process is endothermic. Through the characterization of WV-HAP before and after Cd2+ adsorption, it is found that the adsorption mechanisms are mainly surface adsorption, pore adsorption and ion exchange. The adsorption capacity of WV-HAP to Cd2+ in solution is better than that of HAP, and WV-HAP is a potential Cd2+ adsorption material.

In order to improve the flame retardancy of wood plywood, the intumescent flame retardant coating (IFRC) was prepared by using APP-PER-urea as the basic formula of the system and pyrophyllite as the modified additive. The flame retardancy, hydrophobic and mechanical properties of samples were characterized by means of cone calorimeter, static contact angle machine, scanning electron microscopy, X-ray diffractometer and tensile machine, and the influence of pyrophyllite content on the coating was studied. The results show that adding suitable amount of pyrophyllite in intumescent flame retardant coatings improves the flame retardant effect of coatings. The fire growth index (FGI) reduces by 47%, the fire performance index (FPI) increases by 89%, and the flame retardant index (FRI) increases to 2.5 times when the mass fraction of pyrophyllite powder is 2%. The addition of pyrophyllite powder promotes the formation of continuous and dense carbon layer structure during combustion， produces a molten substance which can effectively isolate oxygen and heat entering the base material and further enhances the flame retardant and thermal insulation properties of the coating. When the mass fraction of pyrophyllite is 2%, the hydrophobic properties of the coating and mechanical properties of wood-made plywood after combustion are the best, and the water contact angle increases by 8°, the tensile strength increases by 45%, and the elongation at break also increases to 8.5 times. The research results can be used as reference for the development of intumescent flame retardant coatings for the wood plywood.

A protective sol (IBIES-TiO2@SiO2 composite sol) was synthesized by sol-gel method with isobutyltriethoxysilane (IBTES), ethyl orthosilicate and butyltitanate as the main components. In this study, a super-hydrophobic self-cleaning coating was prepared in one step by using spray method. The phase composition and micro morphology of IBTES-TiO2@SiO2 and the super-hydrophobicity, self-cleaning and weather resistance of the coating surface after sandstone protection were studied through XRD, FT-IR, SEM, TEM and other measurements. The results show that IBTES-TiO2@SiO2 composite coating has a water contact angle of up to 162°, and has excellent self-cleaning property. After spraying treatment, the water vapor transmission rate of sandstone only reduces by 3.4%. Obviously, the water vapor transmission performance is excellent. When the addition amount of TiO2@SiO2 is 0.7% (mass fraction), it meets the super-hydrophobic performance of sandstone cultural relics while taking into the water vapor permeability. IBTES-TiO2@SiO2 composite coating also has excellent weather resistance. The addition of TiO2@SiO2 particles effectively improves the acid resistance, alkali resistance and ultraviolet aging resistance of sandstone. In 300 h artificial accelerated aging experiment, the surface coating of sandstone still has super-hydrophobic protection properties. IBTES-TiO2@SiO2 composite coating has a good protective effect on sandstone cultural relics. Hence, IBTES-TiO2@SiO2 composite coating is highly promising for the protection of sandstone cultural relics.

Aiming at the problems of insufficient performance and imperfect technical index evaluation method for solvent cold patching asphalt, the composition was optimized, and the optimum preparation process was determined through experiments. A solvent cold patching asphalt with excellent performance was developed by orthogonal experiment, and the performance evaluation method was optimized. The road performance was verified by comparative experiment. The results show that the optimum mixture ratio of the solvent cold patching asphalt is m(asphalt)∶m(diluent)∶m(tackifier)∶m(surfactant)∶m(fortifier)∶m(anti-stripping agent)=100∶（20~25）∶4∶1∶5∶0.2. The optimum preparation process of the solvent cold patching asphalt is determined as follows: add a certain amount of diluent into the 110 ℃ hot melt asphalt, stir with a high-speed shear for 10 min, then add a mixture of quantitative tackifier, fortifier and surfactant, stir continuously for 10 min, finally add a certain amount of anti-stripping agent and stir for 10 min. Taking all factors into consideration, the optimized performance evaluation method can better reflect the road performance of cold patching asphalt. The solvent cold patching asphalt prepared by orthogonal experiment and optimal preparation process is better than the selected finished cold patching asphalt, and can be mixed to produce a mixture with excellent performance.

In grey entropy correlation analysis, the determination of resolution coefficient is the key factor that restricts the analysis result. In this paper, the formula of resolution coefficient was deduced firstly. On this basis, the mixed recycled coarse aggregate was prepared through indoor preparation, and the influence of waste brick on the physical properties of mixed recycled coarse aggregate was studied by the road technical requirements of coarse aggregate. The influence of mixed recycled coarse aggregate on the mechanical properties of cement stabilized macadam was analyzed by the unconfined compressive strength test, and the relationship between the performance index of mixed recycled coarse aggregate and the unconfined compressive strength was analyzed by the grey entropy analysis theory. Through the method of nonlinear data fitting combined with the traffic load grade and the highway grade, the applicable range and the classification of the mixed recycled coarse aggregate were determined in the road engineering base. The results show that the value of resolution coefficient is not fixed, which the maximum and minimum value is 1.000 and 0.141, respectively. The amount of mixture recycled coarse aggregate replacing limestone aggregate does not exceed 20% (mass fraction). Moreover, the proportion of bricks in the mixed recycled coarse aggregate is related to the traffic load grade, and its value could not exceed 40% (mass fraction). Through the grey entropy correlation analysis, the water absorption rate and crushing value are used as grade indexes of the mixed recycled coarse aggregate, of which the application grades are divided into three categories in road engineering.