China has already intended to peak carbon emission before 2030 and achieve carbon neutrality before 2060 in order to coordinate and protect the global climate. The accomplishment of this goal requires the reduction of dependence on fossil energies for energy consumption side and energy supply side. Glass industry plays a significant role in achieving the carbon neutrality target. The glass industry can release huge energy-saving potential through replacements of fuel and raw materials, improvement of energy efficiency, greater use of recycled glass, and development of thin glass. Various energy-saving glass products will show a more obvious energy-saving effect on the energy consumption side. On the energy supply side, glass is also a vital material to support the development of clean energy such as photovoltaics, wind power, and nuclear power. Therefore, glass materials will make a greater contribution to carbon neutrality of China.

The efficient and rational use of pozzolan materials is an important way to achieve environmentally friendly and high performance concrete, while the scientific and accurate evaluation of activity degree is one of the keys to improve its comprehensive application effect. Through the study and analysis of domestic and international literature, the main activity evaluation methods of pozzolan materials, such as chemical test method, physical test method, microstructure analysis method and kinetic model method were outlined. The theoretical basis and applicable characteristics of various evaluation methods were discussed and analyzed. Finally, the shortcomings of the current evaluation were discussed, aiming to provide a reference for the efficient utilization and in-depth research of pozzolan materials.

During the processing of granite stone, a large quantity of waste slurry is produced. The random dumping of waste slurry will do harm to the environment and human health. In recent years, several researchers investigated the use of granite waste sand and powder (GWSP), produced from granite waste slurry, as fine aggregate or cement replacement in cement-based materials. This paper presented the comprehensive overview of the physical and chemical properties of the GWSP. Based on this, the effect and mechanism of GWSP as fine aggregate or cement replacement on the workability, mechanical property, anti-permeability and durability, such as water permeability resistance, chloride permeability resistance, sulphuric acid attack resistance, sulphate attack resistance and reinforcement corrosion of cement-based materials were reviewed. The limitations of the existing studies were analyzed, which will be beneficial for the efficient and high-value-added utilization of GWSP.

Porous zeolite Na-X with larger specific surface area and more ion-exchange capacity is usually applied in wastewater treatment, adsorption and separation of gases, and so on. It is traditionally prepared from the Si and Al-containing inorganic salts. Many minerals and solid waste residues such as coal fly ash, coal gangue, kaolin, oil shale, rice husk ash and bagasse which contain high concentration of Si and Al element can be used for the zeolite Na-X synthesis after pretreatment. The compositions of minerals and solid wastes, as well as the research progress of the synthesis of zeolite Na-X were reviewed, and the pretreatment processes, crystallization kinetics and crystallization mechanism were discussed. Moreover, the effects of synthesis conditions including SiO2/Al2O3 ratio, crystallization temperature and time, anions and cations, H2O/SiO2 ratio, alkali/ash ratio, ultrasonic treatment, and organic additive on the synthesis of zeolite Na-X from minerals and solid wastes were analyzed.

The influence of air-entraining agent, and the enhancement effect of one weak alkaline activator-sodium lactate on the salt frost resistance of supersulfated cement concrete were systematically investigated. Specifically, the surface spalling mass and relative dynamic elastic modulus of ultrasonic of concrete after different cycles of salt freezing were periodically tested, and the air-void structure characteristic was characterized. The results indicate that adding air-entraining agent effectively improves the salt frost resistance of supersulfated cement concrete but with the loss of strength, and the compound addition of sodium lactate avoids strength loss. Adding 0.3% (mass fraction) air-entraining agent of cementitious material, the spalling mass is only 919.7 g/m2, which is 36.8% lower than that of the reference group, and the relative dynamic elastic modulus of ultrasonic is not significantly reduced. The addition of air-entraining agent ameliorates the air-void structure of supersulfated cement concrete, including the reduce of internal pore spacing ecoefficiency and proportion of pore with string length greater than 100 μm. This can slow down the development rate of internal microcracks and delay the failure under freeze-thaw cycles. In addition, sodium lactate promotes the hydration of supersulfated cement and enhances the salt frost resistance of concrete. However, the enhancement effect mainly appears in the late test period. Meanwhile, sodium lactate has little influence on the air-void structure parameters of concrete (28 d).

In order to improve the strength and volume stability of plastering mortar, the effects of cement content and ash-slag ratio (mass ratio of CFB fly ash to CFB slag) on 2 h consistency loss rate, compressive strength and volume stability of CFB fly ash and CFB slag plastering mortar were studied. The micro morphology, element distribution and phase composition of mortar were characterized by scanning electron microscope, X-ray energy spectrometer and X-ray diffractometer. The results show that when the cement content is 5%, 8% and 12% (mass fraction), the strength grade of CFB fly ash and CFB slag plastering mortar reaches M10, M15 and M20, respectively. When the content of cementitious material is constant, the 2 h consistency loss rate of mortar decreases with the increase of cement content. And when the content of cement is constant, the 2 h consistency loss rate of mortar increases and the expansion effect decreases with the increase of ash-slag ratio. Expansive ettringite generated in the CFB fly ash and slag plastering mortar fills the pores between the particles effectively, so as to improve the strength and volume stability of mortar.

Through sieving and crushing, fly ash slag with the particle size range of 0.6 mm to 1.18 mm and 0.3 mm to 0.6 mm were obtained, respectively, and fine aggregate in the corresponding particle size range was replaced by the same volume of fly ash slag. The influence of fly ash slag on the workability and strength of mortar was analyzed, and the optimal alternative particle size range of fly ash slag was explored. Combined with scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and other methods, the strength change mechanism of mortar specimens after the replacement of fine aggregate by fly ash slag was analyzed. Based on the results of the optimal replacement particle size range of the mortar, the strength and frost resistance of the mortar concrete specimens were verified. The results show that: after sieving and crushing to obtain fly ash slag in the particle size range of 0.3 mm to 0.6 mm to replace the fine aggregate in this interval, the strength of the mortar specimens is the same as that of the benchmark group; sieving to obtain the fly ash slag in the particle size range of 0.3 mm to 0.6 mm to replace this interval, the strength and frost resistance of the concrete specimens are the same as those of the benchmark group. Under the calcium hydroxide environment provided by cement, calcium silicate hydrate is formed on the surface of fly ash slag, thereby increasing the cement and fly ash slag interface bonding strength, strengthening the interface area between the cement and the fly ash slag. The uneven surface is interlocked with the cement slurry to ensure the strength of the specimen.

The performance of recycled aggregate (RA) was improved by pre-soaking the RA in nano-SiO2 solution to enhance its weak surface. A mesoscopic model of multi-phase for recycled aggregate concrete (RAC) was established to simulate the chloride ion transportation in concrete. Experiments of RAC immersing in chloride ion solution were carried out to verify the simulation results, and service life of RAC exposed in chloride ion environment was predicted. The results indicate that the mesoscopic numerical simulation results are in good agreement with the experimental results. At the same depth, the closer to the aggregate surface, the greater the chloride ion concentration, and the concentration of chloride ion on the surface of un-strengthened RA is higher than that on the surface of strengthened RA. Increasing the thickness of protective layer effectively improves the durability life of the nano-strengthening RAC in chloride environment. The durability life of RAC increases a little with the decrease of chloride ion diffusion coefficient of nano-coating layer.

In order to better realize the resource utilization of heavy metal sludge, ground powder mixed with heavy metal sludge and architecture sediment for high-temperature harmless treatment was investigated on the work performance, mechanical properties, early shrinkage deformation, chloride ion permeability resistance, and heavy metal leaching of Portland cement-based materials. The results show that with the increase of ground powder content, the work performance of Portland cement-based materials does not decrease, but the mechanical properties decrease to a certain extent, which indicates that the water requirement ratio of ground powder and Portland cement is not much different. But the larger the content of ground powder is, the lower the cement content in cement-based materials is, and the strength decreases to a certain extent. The ground powder does not cause the volume stability of the Portland cement-based materials and improves the early crack resistance, but it reduces chloride ion permeability resistance. The leaching concentration of heavy metals and the decrease of water-binder ratio are negatively correlated with the increase of age, and the leaching amount of heavy metals Cu, Ni, Zn and Cr in Portland cement-based materials containing 40% (mass fraction) ground powder at 28 d is lower than the limit value of cement clinker leaching concentration specified in GB 30760-2014 “Technical specification for cement kiln cooperative disposal of solid waste”.

Ultra-high performance concrete (UHPC) was prepared by ultrafine and highly active mineral admixtures (ultrafine admixtures) and silica fume in single or compound admixture. The effects of ultrafine admixtures with different dosage on the workability, mechanical properties, hydration heat and shrinkage properties of UHPC were analyzed. The results show that the fluidity of UHPC increases with the increase of the ultrafine admixtures, and the highest fluidity of jumping table is 275 mm. When UHPC is prepared by mixing the ultrafine admixtures with 10% (mass fraction) silica fume, the flexural strength increases first and then decreases with the increase of ultrafine admixture, while the compressive strength increases first and then keeps steady. The maximum flexural strength and compressive strength are 25.9 MPa and 150.0 MPa, repectively. The hydration heat of UHPC cementitious material prepared by compounding ultrafine admixture and 10% (mass fraction) silica fume increases at first and then decreases with the increase of ultrafine admixture. The early shrinkage of UHPC prepared by compounding the ultrafine admixture and silica fume with a mass fraction of 10%, is the smallest, which is 50.92% lower than that of UHPC prepared by silica fume with a mass fraction of 20% alone.

In order to study the effect of reclaimed asphalt pavement (RAP) content on the mechanical properties of self-compacting concrete (SCC), SCC samples with RAP content of 0%, 30%, 60%, 90%, and 100% by weight replacement were prepared. Stress-strain relationship and toughness index of samples were studied by uniaxial compression test. The uniaxial compression damage constitutive model based on the strain equivalence hypothesis and statistical damage theory was established. Damage variable and damage variable development rate of samples with different RAP content were studied. The results show that compared with SCC, with the increase of RAP content, the peak stress and elastic modulus decrease and the peak strain and toughness index increase. The constitutive damage model describes the stress-strain relationship of SCC with different RAP content effectively. When the strain is less than 0.002, the damage variable value of SCC samples with RAP is larger than control SCC sample and the damage variable value of samples increases with the increase of RAP content. When the strain is larger than 0.002, the damage variable value of SCC samples with RAP is less than control SCC sample, and decreases with the increase of RAP content. With the increase of RAP content, the damage variable development rate of RAP self-compacting concrete decreases continuously and the damage rate shows a trend of increase first and then decrease.

Microbially induced carbonate precipitation (MICP) can effectively heal the cracks of concrete. However, suitable carriers should be adopted to reduce the adverse effect of cement hydration and high alkalinity. Recycled coarse aggregates (RCAs) are favorable bacteria carrier to prepare self-healing concrete. Meanwhile, MICP can effectively enhance the physical and mechanical properties of RCAs. A self-healing recycled concrete, based on RCAs enhanced by MICP of mixed cultures of bacteria, was proposed to ensure its sufficient mechanical properties and excellent self-healing capacity. A kind of alkaliphilic and aerobic mixed cultures of bacteria with high MICP capacity was firstly enriched and selected. Then, the self-healing recycled concrete was prepared using the RCAs enhanced by MICP of mixed cultures of bacteria. The self-healing capacity of concrete was subsequently investigated. It shows that MICP of mixed cultures of bacteria can effectively enhance the physical and mechanical properties of RCAs. The RCAs enhanced by MICP of mixed cultures of bacteria for 5 d can effectively immobilize the mixed cultures of bacteria. The concrete specimens with mixed cultures of bacteria exhibit much better self-healing capacity compared with specimen with pure culture. The concrete specimens using RCAs as bacterial carrier exhibit better self-healing capacity compared with specimen using ceramsite. The value of completely healed cracked width is up to 0.47 mm. The results of the present study are expected to provide a reference for resource utilization of construction waste and durability of recycled concrete.

Sludge from water treatment plant is a by-product of water treatment and an important solid waste. The influence of mechanically activated water treatment plant sludge ultrafine powder (WTSP) on mechanical properties, microstructure of recycled concrete (RC) was studied. The results show that the incorporation of WTSP reduces the mechanical properties of RC at early age, but makes positive improvement at the later stage. The compressive strength and elastic modulus of the sample containing 20% (mass fraction, the same below) WTSP at 60 d are 13% and 9% higher than those of the reference group, respectively. The number of harmful pores (>100 nm) in the sample reduces by 37.5% and 54.6%, respectively, and the microstructure improves significantly after addition of 10% and 20% WTSP into RC. Nano-indentation analysis shows that the width of interfacial transition zone (ITZ) in RC sample with 20% WTSP added decreases by 20% to 25%, and the elastic modulus of ITZ and new mortar increases. This may be related to the nucleation, the micro-aggregate filling and the pozzolanic effect of WTSP.

A kind of low cost and environmental protection ultra-high performance concrete (UHPC) was prepared. According to the modified Andreasen and Andersen model, the mix proportion design was carried out. Using waste incineration slag instead of the river sand to prepare different replacement rates of UHPC, and the working performance, mechanical properties, pore characteristics, hydration process, microscopic characteristics and toxic consolidation performance were tested. The results show that with the addition of garbage residue, the working performance and compressive strength of UHPC decrease， but the fluidity is no less than 240 mm and the compressive strength is no less than 117 MPa. The cumulative pore content increases, most of the pores are distributed in the harmless pore range of <20 nm, and the cracks in the transition zone of concrete interface increase.The concentration of Zn, Pb and Cr in concrete are all lower than the limit value of national standard, which achieves effective consolidation of heavy metals.

Alkali-activated non-sintered ceramsite was prepared with fly ash as raw material and silica fume as supplemented agent. The effect of silica fume content on ceramic properties was systematically studied by means of cylinder compressive strength test, water absorption test, mud content test, abrasion rate test, corrosion resistance test, X-ray diffractometer measurement and scanning electron microscope examination. The results show that at the age of 3 d, 7 d, and 14 d, as the content of silica fume increases, the cylinder compressive strength of fly ash ceramsite gradually increases, while the abrasion rate and water absorption decrease gradually, and the corrosion resistance is also improved. When the silica fume content is 15% and 20% by mass, and the age is 14 d, the cylinder compressive strength of the ceramsite reaches 19.43 MPa and 20.37 MPa. According to the microscopic analysis, appropriate silica fume content increases the hydration degree of fly ash and the compactness of the ceramsite structure, but when the content reaches 15% to 20% by mass, the hydration degree is weakened.

This paper revolves around the research and production of non-clinker and non-sintered ceramsite with perlite tailings, granulated blast furnace fine slag powder, and water glass as raw materials. The combined influence of the modulus and content of water glass on the intensity of fine slag powder with sodium silicate as activator, and the effect of the combination of fine slag powder and perlite tailings powder on the compressive strength and bulk density of ceramsite cylinders were explored. The results show that when the mass ratio of slag powder to water glass is 90∶10, the best modulus of water glass is 1.06, and the mass ratio of slag powder to perlite tailings is 90∶10, the ceramsite can reach a technical performance on a 28 d standard maintenance that compressive strength of cylinder is 7.50 MPa, the density grade is 900 kg/m3, the porosity is 31.84%, the softening coefficient is 0.92, the mud content is 2.25%, and the boiling mass loss is 2.84%. Besides, after water proof treatment on the surface of the ceramsite, reducing the water absorption rate decreases from 11.68% to 4.88%. The ceramsite is used to prepare LC30 lightweight aggregate concrete for the application of the road base around manholes. The 28 d compressive strength is 35.5 MPa, the density grade is 1 700 kg/m3, and the compression coefficient is 0.001. The application presents a satisfying result, preventing the sinking of the urban road manholes.

Coal gasification slags can be divided into coarse slag and fine slag, which has potential application in alkali-activation field. The physical and chemical properties of coal gasification coarse slag were studied, and the geopolymer was prepared by using coal gasification coarse slag, meanwhile geopolymer modified by TiO2 was studied. The results show that the mechanical properties of coal gasification coarse slag based geopolymer significantly improve by adding a certain amount of TiO2. When 10.0% (mass fraction) TiO2 is added, the 28 d compressive strength of the sample increases from 23.4 MPa to 42.9 MPa. In addition, through phase and microstructure analysis of the samples, the addition of TiO2 significantly improves the microstructure of the geopolymer, promotes the alkali-activation reaction, and improves the mechanical properties of the material.

In this paper, the effect of shrinkage reducing agent (SRA) on the mechanical property and drying shrinkage of alkali-activated coal gangue-slag (AACGS) cementitious materials was investigated. And the variation of hydration heat, hydration products and microstructure with incorporating SRA was further discussed. The results show that incorporation of 3% （mass fraction） SRA significantly reduces the mechanical property of AACGS cementitious materials, but the reduction amplitude gradually decreases with the progress of hydration. The drying shrinkage decreases significantly with the increase of SRA content. Microscopic analysis shows that the addition of SRA does not lead to the formation of new hydration products, but delayes the hydration reaction, inhibites the early polymerization of alkali-activated materials and increases the porosity of alkali-activated cementious materials, which causes the decrease of mechanical property of AACGS cementious materials with SRA. In addition, SRA does not significantly change the concentration of alkali metal ions in pore solution. The delay of hydration process and the formation of solid phase structure caused by the addition of SRA are the main reasons for reducing the drying shrinkage of AACGS mortar.

In order to promote large quantity and high value-added utilization of steel slag mud, the hydration and hardening characteristics of steel slag mud from Qian’an of Hebei under blast furnace slag and desulphurization gypsum were investigated with XRD, FE-SEM, FT-IR and TG-DTA. The results indicate that the steel slag mud still shows good hydrated cementitious property after mechanical grinding. Compared with ordinary steel slag-blast furnace slag-desulphurization, the compressive strength of cementitious materials has the advantage of high early strength. Its hydration products are mainly AFt and C-S-H gel. During the hydration reaction process, the steel slag mud provides an alkaline environment for the system and promotes the dissociation of the vitreous in the slag. The slag hydration continuously consumes hydroxyl groups to further promote the hydration of the steel slag mud. The desulfurized gypsum provides a large amount of Ca2+and SO2-4, which react with gel in the system to produce AFt. The three materials interact with each other to synergistic reaction and promote the continuous hydration reaction.

The phosphogypsum (PG) was heat-treated in an oven with a constant temperature, and the phosphogypsum-based composite cementitious material (PGCM) was prepared by adding lime calcium powder, normal Portland cement, retarder and water reducing agent. The effects of heat treatment time on the splitting tensile strength of PGCM, the reduction coefficient of axial compressive strength and splitting tensile strength, the failure morphology, and the splitting tensile stress-strain curves were studied. The results show that the splitting tensile strength increases first and then decreases with the extension of heat treatment time. When the heat treatment time is 90 min, the splitting tensile strength reaches the maximum 1.68 MPa. The reduction coefficients of axial compressive strength and splitting tensile strength almost reduce with the extension of heat treatment time. The splitting tensile strength is 42% to 92% of axial compressive strength. The failure morphology of PGCM mainly including central cracking failure, local failure and minor crack failure. The splitting tensile stress-strain curves of PGCM gradually rise first and then decrease linearly. Combined with the test data, the conversion relationship between the axial compressive strength and splitting tensile strength of PGCM, and the equation of splitting tensile stress-strain rising section curves are obtained. The fitting results are in good agreement with test data.

In order to promote the resource utilization of waste slag from stainless steel factory, the cementification materials were prepared with laterite nickel mine acid furnace slag and stainless steel slag as the main raw materials. The effects of mechanical activation and the mass addition amount of stainless steel slag on the properties of cementing materials were studied. The hydration products and microstructure of cementing materials were analyzed by XRD and SEM. The results show that mechanical activation is mainly through the changes of specific surface area and particle size distribution of raw materials to affect the properties of cementing materials, and the proportion of fine particles in blast furnace slag is the crucial factor affecting the cementing activity, the optimal ball milling time is 45 min, and the specific surface area of blast furnace slag is 524.66 m2/kg. There is a synergistic action between stainless steel slag and acidic slag. When the mass content of stainless steel slag is 20%, with curing ages of 3 d，7 d and 28 d, the compressive strength of mortar test block is 17.8 MPa, 24.3 MPa and 34.8 MPa, and the flexural strength is 4.5 MPa, 6.2 MPa and 6.8 MPa, respectively, which reaches the requirement of P·S 32.5R slag Portland cement strength standard. The addition of stainless steel slag facilitates the formation of ettringite and C-S-H gel at the early and late hydration stages, which increases the strength of mortar test block at various ages. The fine particles of steel slag without hydration also play a micro-aggregate filling role, which is conducive to the improvement of the early strength of cementing materials.

Porous geopolymer materials were prepared with steel slag as the main raw material, water glass as the activator and H2O2 as the foaming agent. The raw materials and final samples were characterized by XRD, FTIR, SEM and BET. The effects of calcium silicon ratio, activator and H2O2 admixture on the properties of the material were studied. The porous geopolymer was used as adsorbent to investigate the adsorption effect of Cu2+. It shows that when the calcium-silicon ratio is 1.0, water glass mixing is 20.4% (mass fraction) and foaming agent mixing is 4% (mass fraction), the material performs well, with 86.4% total porosity, 0.5 MPa compressive strength, 0.408 g/cm3 volume density, volume water absorption rate is 56.31%, and steel slag utilization rate is 65.85%, significantly improving the specific surface area and pore capacity. The adsorption results show that the material has a good adsorption effect on Cu2+, the removal rate reaches 91.44%, and the equilibrium adsorption amount reaches 15.239 mg/g. The adsorption process conforms to the pseudo-second order.

In this paper, steel slag based admixtures (GKF) were taken as the research object. Based on the single factor experiment, the best combination scheme of activator Na2SO4, silicon slag and desulfurized gypsum is investigated by orthogonal experiment. The suitable mass proportion is 2.0%Na2SO4, 0.5%silicon slag and 1.5%desulfurized gypsum, The results show that the activity of the mortar prepared by replacing P·I 42.5 with 50%GKF is 77.3%, 85.9% and 96.6% at 3 d, 7 d and 28 d, respectively. Compared with the group without activator, the activity increases by 24.2%, 25.4% and 22.4%, respectively. XRD and SEM were used to analyze the structure and micro morphology of the hydrated minerals. The results show that the composite activator is helpful to the hydration of GKF, which increases the content of C-S-H and AFt, and makes the structure more compact.

In this paper, the effects of the mass ratio of magnesium-rich nickel slag and fly ash, the content of composite alkali activator (sodium silicate-Na2CO3) and water binder ratio on the mechanical properties of magnesium-rich nickel slag-fly ash based geopolymer were studied by orthogonal test. The products were characterized by XRD, SEM, EDS and TG. The results show that the 28 d compressive strength of the optimal sample reaches 37.50 MPa. XRD results shows that calcium silicate gel form in the products of 7 d and 28 d. SEM and EDS analysis show that there are chabazite (N-A-S-H) and sodium magnesium aluminum silicate gel (N-M-A-S) amorphous gel phases in the products. These gel phases are the main reasons for the increase of the strength of geopolymer.

The high temperature desulfurization of electrolytic manganese filter press residue was studied by direct calcination method, reduction method and calcination method with adding desulfurizer. The phase, residual sulfur content and activity of desulfurization products by different methods were studied, and the industrial applicability of several methods was compared. The results show that desulfurization slag by direct calcination method sticks seriously with crucible and it is difficult to operate in practice. The desulfurization slag by calcinations with adding coal still sticks with crucible, and contains high amount of residual sulfur. Although limestone weakens the adhesion between desulfurization slag and crucible, the activity of desulfurization slag reduces due to the formation of inert material quartz. Desulfurization slag from manganese residue with bauxite has low residual sulfur, high activity, and no adhesion to crucible. So, bauxite is a good desulfurizer for manganese residue. When the addition amount of bauxite is 42% (mass fraction), the desulfurization temperature is 1 250 ℃, and the desulfurization holding time is 5 min, the sulfur content in the desulfurization slag is 0.089 4% (mass fraction), which meets the desulfurization requirements.

Using Al powder, Al-12Si and Al-20Si alloy powder as phase change medium and fly ash as matrix material，metal/ceramic based high-temperature shaped composite phase change materials were prepared by mixed sintering method under air and vacuum sintering atmosphere. The effects of the Al-Si relative content and sintering atmosphere on the heat storage performances of materials were investigated. The results show that the oxidation of Al is inevitable when the three kinds of metal powders are used to prepare composite phase change materials, the relative content of Si exceeds the eutectic point composition. The state point during solidification is always in the two-phase zone of eutectic phase and Si phase, and the unoxidized Al transforms into Al-Si eutectic phase. Sintering in air is beneficial for Al to form a dense oxide film and prevent its further reaction. The density and latent heat of phase change of materials sintered in air are higher than those sintered in vacuum. Among the three kinds of composite phase change materials, Al powder composite phase change material has the worst thermal stability, while Al-12Si composite phase change material has the highest latent heat of phase change and retention rate, and outstanding thermal stability and heat storage performance.

Although coal gangue as solid waste is used in electricity generation, coalmine backfilling and building materials, its utilization rate is still not high. How to improve the high-value utilization of coal gangue has become a research hotspot. In this paper, Al2O3-SiO2 aerogel powder was synthesized by one-step acid leaching followed by sol-gel method and ambient pressure drying from coal gangue. Ultrasonic was exerted in the process of solvent replacement and modification. The structure and performance of Al2O3-SiO2 aerogel powder were characterized by means of BET, XRD, SEM, FT-IR, TG-DSC and contact angle measurement. The results show that the reaction rate is accelerated by ultrasonic and the preparation cycle is shortened. Al2O3-SiO2 aerogel is a mesoporous material with three-dimensional network structure of nano. Al2O3-SiO2 aerogel has a minimum bulk density of 0.120 g/cm3 and a specific surface area of 635 m2/g, its shrinkage at high temperature is lower than that of SiO2 aerogel prepared from sodium silicate, Al2O3-SiO2 aerogel also shows high hydrophobicity.

Cement slurry powder contains components that can adsorb heavy metal ions, which can be used as adsorbent to treat wastewater containing heavy metal ions. In this experiment, ordinary Portland cement was used to prepare cement slurry powder with different hydration ages to treat wastewater containing Pb2+. The effects of age and dosage of cement slurry powder, Pb2+ concentration, pH value, temperature and adsorption time on Pb2+ removal effect and adsorption behavior were studied by means of X-ray diffraction, synchronous thermal analyzer and inductively coupled plasma. The test results show that the removal rate of lead ion in wastewater by cement slurry powder is generally greater than 80%. When 0.04 g cement slurry powder with water cement ratio of 0.50 and hydration age of 60 d is used for Pb2+ solution with initial concentration of 700 mg/L at 35 ℃, pH=2 and adsorption time of 200 min, the Pb2+ removal rate is 96.06% and the adsorption capacity is 336.22 mg/g. Through the study of adsorption thermodynamics and adsorption kinetics, it can be obtained that the adsorption thermodynamics of cement slurry powder for Pb2+ conforms to Freundlich adsorption isothermal model, and the adsorption kinetics conforms to pseudo first-order kinetic model.

Magnetized red mud adsorption material (ATMMRM) modified by alcohol-amine titanate was prepared from industrial solid waste red mud (RM) after reducing calcination and grafting modification. Using XRD, FT-IR, SEM, BET, VSM and other characterization methods to characterize and compare RM and ATMMRM. The results show that the surface of ATMMRM is successfully introduced with hydroxyl and amine groups, and the specific surface area and saturation magnetization of ATMMRM are 6.0 and 9.6 times higher than those before modification, respectively. These properties provide more active adsorption sites for the adsorption of Pb(Ⅱ) by ATMMRM and endow the material with magnetic separation ability. The results of static adsorption experiments show that the saturated adsorption capacity of ATMMRM for Pb(Ⅱ) in aqueous solution reach 213 mg·g-1 at pH=6 and T=25 ℃. The adsorption process of Pb(Ⅱ) from aqueous solution by ATMMRM conforms to Langmuir isotherm model and pseudo-second-order kinetic equation, and is controlled by chemisorption process with spontaneous endothermic entropy increase. The main adsorption mechanism are physical adsorption and chelation of Pb(Ⅱ) with hydroxyl and amine groups grafted on the surface of ATMMRM.

The high crystallinity of zeolite NaA were prepared by hydrothermal method based on the combination of calcined silico-manganese slag (Si-Mn slag) and fly ash. The influence of n(SiO2)/n(Al2O3), the concentration of NaOH, hydrothermal temperature and hydrothermal time on products were studied by single factor experiment. The results show that the zeolite NaA with good crystallinity and thermal stability can be synthesized at the condition of the mass ratio of calcined silico-manganese slag and fly ash=1∶1, n(SiO2)/n(Al2O3)=2.2, temperature of 90 ℃, alkalinity of 2 mol/L and reaction time of 4 h. Compared with the traditional synthesis of the zeolite NaA with fly ash as raw material, the addition of silico-manganese slag makes it a composite system, providing a new way for the resource utilization of silico-manganese slag.

In order to realize the high value utilization of gold tailings, the ceramic facing brick was prepared by pressureless firing method with gold tailings as the main raw material. The effects of gold tailings addition on phase composition, microstructure and properties were investigated. The results reveal that the sample with 70% (mass fraction) gold tailings fired at 1 100 ℃ has the optimal bending strength of 73.42 MPa, water absorption of 0.10%, porosity of 0.25%, bulk density of 2.46 g/cm3 and firing shrinkage of 8.64%. The performance meets the requirements of Chinese national standard GB/T 4100-2015 “Ceramic tiles”. The phases of the samples are anorthite, quartz, leucite and hematite. The glaze surface of the facing brick is smooth with uniform color, and the binding property between the body and glaze of the facing brick is excellent.

Four pyrolysis temperatures (300 ℃, 400 ℃, 500 ℃, 600 ℃) semi-coke were selected, and the microstructure of oil shale semi-coke was analyzed by scanning electron microscopy (SEM), and then equal masses of oil shale semi-coke (0%, 5%, 10%, 15%, 20%, 25%) were used to replace cement. The standard consistency water requirement, the fluidity of mortar and the flexural and compressive strength of cement sand at different ages were tested. The results show that the semi-coke of oil shale is lamellar and porous. With the increase of pyrolysis temperature, the number of micropores and small pores gradually decreases, and the number of medium and large pores increases. Adding oil shale semi-coke increases the water requirement of standard consistency and reduces the fluidity of mortar. There is a strong linear relationship between the content of oil shale semi-coke and the water requirement of standard consistency. With the increase of the pyrolysis temperature of oil shale semi-coke, the flexural and compressive strength of cement sand increases first and then decreases, and the mechanical properties reach the best at 500 ℃. With the increase of the amount of oil shale semi-coke, the flexural and compressive strength of cement sand gradually decrease. When the oil shale semi-coke content is 15%, the mechanical properties of the 56 d pyrolysis semi-coke cement sand at 500 ℃ are close to that of the P·Ⅰ 42.5 benchmark cement sand.

To improve the anti-cracking property of steel slag-asphalt mixture (SAM), and minimize the effect of steel slag (SS) expansion characteristics on the durability of asphalt mixture， the comparative research on the effects and reinforcement mechanism of different contents of basalt fiber (BF) on the high and low temperature performance, water stability and fatigue property of SAM was implemented via rutting test, SPT dynamic modulus test, low temperature bending test, freeze-thaw splitting test, bending fatigue test, SEM test, etc. Results show that the addition of BF improves the high temperature anti-deformability, and increases the low temperature flexibility of SAM with different SS content to a certain extent. With the increase of freeze-thaw cycles, the decrease of water stability of BF-SAM is significantly lower than that of ordinary SAM. The reinforcement and crack resistance of BF improve the fatigue life of SAM. After comprehensive consideration of various road performance, the recommended BF content of BF-SAM is 4% （mass fraction） and the recommended SS content range is 45% to 55% （mass fraction）.

To research the self-healing performance of steel slag asphalt mixtures by microwave heating, four kinds of asphalt mixtures were prepared: whole stone type, coarse stone fine steel slag type, coarse steel slag fine stone type and whole steel slag type. The thermal and electromagnetic parameters of asphalt mixtures were measured by thermal constant analyzer and vector network analyzer. The temperature distribution of asphalt mixtures was measured by thermocouple temperature sensor and infrared thermometer. The numerical simulation temperature field of COMSOL software and test temperature distribution were compared and analyzed. Finally, the self-healing performance of asphalt mixtures was evaluated by three-point bending failure test. The results show that the four asphalt mixtures have different microwave absorption and heat transfer properties, and have a certain impact on the heating rate of asphalt mixtures. The addition of steel slag greatly improves the microwave heating performance of asphalt mixtures, and the coarse stone fine steel slag in the three steel slag asphalt mixtures shows better heating uniformity. COMSOL software simulates the temperature distribution of asphalt mixtures under microwave heating. Compared with the whole stone asphalt mixtures, the self-healing performance of coarse stone fine steel slag, coarse steel slag fine stone and whole steel slag asphalt mixture increase by 1.11 times, 1.14 times and 1.11 times, respectively. The addition of steel slag improves the self-healing performance of asphalt mixture.

The foamed mixture lightweight soil was prepared by tailings. The effects of wet density and tailings concent on the mechanical property and frost resistance of lightweight soil were researched, and the effects of tailings on the pore structure of lightweight soil were researched. The results show that the compressive strength of foamed mixture lightweight soil is positively correlated with wet density and negatively correlated with tailings content. When the content of tailings reaches 45% （mass fraction, the same below）, the compressive strength of light soil with 700 kg/m3 and 800 kg/m3 wet density is 0.97 MPa and 1.40 MPa respectively, which is about 69% and 66% lower than that of lightweight soil without tailings. Tailings foamed mixture lightweight soil has good frost resistance. In 30 freeze-thaw cycles, the loss rate of compressive strength of lightweight soil with 700 kg/m3 wet density of 0% to 45% tailings is less than 15%, and the compressive strength is greater than 0.80 MPa. Improving the wet density grade can further improve the frost resistance of lightweight soil. The addition of tailings will increase the porosity and average pore diameter of lightweight soil and reduce the pore roundness. Compared with the lightweight soil without tailings, when the content of tailings reaches 30%, the porosity increases by 3.58%, the average pore size increases by 16.7%, and the roundness increases by 7.4%.

The phosphogypsum and copper tailings sand are mixed to prepare a mixture, and cement is added for highway roadbed filling, which can realize the large-scale utilization of solid waste resources and the purpose of “waste treatment by waste”. The geotechnical performance test of the mixture was used to explore the influence of the mass ratio of phosphogypsum and copper tailings sand on the mixture’s geotechnical performance, combined with modern analysis and testing technology to study the hydration-hardening mechanism and micro-mechanism of the mixture. The results show that neither phosphogypsum nor copper tailings sand can be used alone as roadbed filling materials because of the higher liquid limit of phosphogypsum and the lower strength characteristics of copper tailings sand. When phosphogypsum and copper tailings sand are mixed with a mass ratio of 4∶6, the geotechnical performance of the mixture was better. The hardening of the mixture is caused by the hydration of the cement. Hydration products such as ettringite and C-S-H gel can fill the gap between the particles of the mixture and form a compact aggregate, which causes the mixture to harden.

River sludge is usually stabilized with cementitious binder and applied in pavement construction as sub-ground soil for sustainable treatment. However, the application of Ca-based binder, such as Portland cement and lime, is increasingly limited by the high energy consumption and CO2 emission. To solve this problem, granulated blast furnace slag (GBFS) and fly ash were used to synthesize binary-phases based geopolymer to stabilize sludge. Firstly, the mix proportion of geopolymer stabilizer was determined based on the influence of Si/Al and Na/Al molar ratio on the setting time and compressive strength of geopolymer. Subsequently, the effects of geopolymer content and curing age on the mechanical properties of stabilized sludge are studied, and the practical performance of stabilized sludge was evaluated with water stability, CBR, dry shrinkage and temperature shrinkage tests. Furthermore, the stabilization mechanism was revealed by the microstructure characterization with scanning electron microscopy and X-ray diffractometry. The experimental results show that the geopolymerization products include amorphous geopolymer gel, calcium silicate hydrate and calcium aluminate hydrate, which enhance the binding of soil particles and filled the voids, and thus improve the mechanical properties and road performance of stabilized sludge. It provides experimental foundation for the practical application of geopolymer stabilized sludge in pavement construction.

Through bending beam rheological (BBR) test, contact angle measurement and atomic force microscope (AFM) test, the low temperature crack resistance of warm mix crumb rubber powder modified asphalt (WCR) before and after aging and its adhesion change law to aggregate were studied from macroscopic and microscopic perspectives, and hot mix crumb rubber powder modified asphalt (HCR) was used as a comparison. The results show that with the increase of aging degree, the ratio of creep rate (m) to bending creep stiffness (S) (m/S) of HCR and WCR decreases, and the low temperature crack resistance becomes worse. The low temperature crack resistance and aging resistance of WCR are better than HCR. The adhesion of HCR, WCR to three kinds of aggregates before and after aging is limestone > basalt > granite, and the adhesion of WCR to aggregates is better than that of HCR. The micro Derjaguin-Muller-Toporov (DMT) modulus of the two asphalts before and after aging has a good linear relationship with the low temperature rheological parameter (m/S), and the micro surface energy and adhesion work obtained based on Johnson-Kendall-Roberts (JKR) mechanical model has a strong correlation with the macro surface energy and adhesion work obtained based on the surface energy theory.

Ammonia nitrogen in electrolytic manganese residue (EMR) is the main factor limiting its comprehensive utilization, and oxalic acid leaching technological can effectively remove ammonia nitrogen from EMR. In this paper, the technological conditions affecting the leaching of ammonia nitrogen from electrolytic manganese residue were studied. The material changes were characterized by FT-IR, XRD, XPS, SEM and EDS. The leaching model of ammonia nitrogen was established by kinetic analysis and thermodynamic calculation, and the leaching mechanism was discussed. The results show that when the liquid to solid ratio is 2, the amount of oxalic acid is 10% and the leaching time is 20 min, the residual concentration of ammonia nitrogen is 13.85 mg/L and the ammonia removal rate is 98%. Ammonium phosphate in electrolytic manganese residue mainly exists in the crystal lattice of insoluble calcium sulfate, oxalic acid facilitate the release of ammonium phosphate from the calcium sulfate interlattice. The leaching rate of ammonia nitrogen is controlled by chemical reaction and interfacial mass transfer mixing, and the energy release is the most and the structure is the most stable when ammonium ion and oxalic acid are coordinated 1∶1.

In this paper, the transformation of gypsum to anhydrite phase in titanium gypsum-H2SO4-H2O system under atmospheric pressure was studied. The effects of reaction time, sulfuric acid concentration and temperature on the transformation of gypsum to anhydrite were explored. The results show that increasing reaction temperature, sulfuric acid concentration and reaction time are beneficial to the transformation of gypsum to anhydrite. When gypsum is converted to anhydrite, the anhydrite do not change after prolonging the reaction time. When the temperature is 70 ℃ and 80 ℃, gypsum and anhydrite coexist in the system, and there are obvious differences in the microstructure, gypsum is flake, and anhydrite is rectangular plate. When the temperature rises above 90 ℃, gypsum is completely transformed into anhydrite, and its microscopic appearance is rectangular plate. Under atmospheric pressure, in the range of 50 ℃ to 100 ℃, gypsum-anhydrite transformation occurs in the system of titanium gypsum-H2SO4-H2O system, gypsum is directly dehydrated to anhydrite, no intermediate products are formed in the process.

Steel slag and ground granulated blast-furnace slag are two common industrial waste slags, which are piled up in large quantities and are difficult to use as resources. Using steel slag powder and blast-furnace slag powder as basic materials, and calcium carbide slag powder as activator， the muddy soil was solidified. The strength characteristics and stress-strain relationship of solidified muddy soil by carrying out unconfined compressive strength tests were analyzed. X-ray diffraction (XRD) and scanning electron microscopy (SEM) microscopic tests were used to explore the mechanism of calcium carbide slag activated steel slag and ground granulated blast-furnace slag solidified muddy soil. The results show that when the content of calcium carbide slag powder is 6%, the unconfined compressive strength of calcium carbide slag-steel slag-blast furnace slag solidified muddy soil is the highest. The 28 d solidified muddy soil has the same strength as cement solidified muddy soil of the same age and has good ductility. Calcium carbide slag provide an alkaline environment and a large amount of calcium ions, effectively stimulate the hydration activity of steel slag and blast furnace slag, promote the mass production of C-S-H gel, and promote ion exchange and agglomeration, so that the strength of solidified muddy soil is significantly improved.

In view of the high cost and serious environmental pollution caused by the disposal of municipal solid waste incineration (MSWI) fly ash, a method for preparing unburned microbial MSWI fly ash brick, using the principle of microbial mineralization, is proposed. The solidification and stabilization of heavy metals in MSWI fly ash were achieved by adding microbial bacteria liquid to the MSWI fly ash brick consolidation body and using the principle of microbial induced carbonate deposition. In this paper, MSWI fly ash, Ca(OH)2, sand and microbial bacteria were used as raw materials, and the optimal MSWI fly ash content, microbial bacterial solution concentration and calcium ion concentration in nutrient solution for the preparation of microbial MSWI fly ash brick were explored through single factor experiment. The test results show that when the MSWI fly ash content is 40% (mass fraction), the OD600 value of the microbial bacterial solution is 0.60, and the Ca2+ concentration in the nutrient solution is 0.30 mol/L, the mechanical properties of the MSWI fly ash brick are the best. At this time, the dry density of the 100 mm×100 mm×50 mm unburned microbial MSWI fly ash brick is 1 937.40 kg/m3, the compressive strength reaches 33.90 MPa, and the heavy metal leaching concentration meets the limit requirement, realizing the resource utilization of MSWI fly ash.