The evolution of the microstructure and morphology of Cu55Ni45 and Cu60Ni40 alloys under varying degrees of undercooling was investigated through molten glass purification and cyclic superheating technology. By increasing the Cu content, the effect of Cu on the evolution of the microstructure and morphology of the Cu-Ni alloy during undercooling was studied. The mechanism of grain refinement at different degrees of undercooling and the effect of Cu content on its solidification behaviour were investigated. The solidification behaviour of Cu55Ni45 and Cu60Ni40 alloys was investigated using infrared thermometry and high-speed photography. The results indicate that both Cu55Ni45 and Cu60Ni40 alloy melts undergo only one recalescence during rapid solidification. The degree of recalescence increases approximately linearly with increasing undercooling. The solidification front of the alloy melts undergoes a transition process from a small-angle plane to a sharp front and then to a smooth arc. However, the growth of the subcooled melt is constrained to a narrow range, facilitating the formation of a coarse dendritic crystal morphology in the Cu-Ni alloy. At large undercooling, the stress breakdown of the directionally growing dendrites is primarily caused by thermal diffusion. The strain remaining in the dendritic fragments provides the driving force for recrystallisation of the tissue to occur, which in turn refines the tissue.

The multi-scale modeling combined with the cohesive zone model (CZM) and the molecular dynamics (MD) method were preformed to simulate the crack propagation in NiTi shape memory alloys (SMAs). The metallographic microscope and image processing technology were employed to achieve a quantitative grain size distribution of NiTi alloys so as to provide experimental data for molecular dynamics modeling at the atomic scale. Considering the size effect of molecular dynamics model on material properties, a reasonable modeling size was provided by taking into account three characteristic dimensions from the perspective of macro, meso, and micro scales according to the Buckingham π theorem. Then, the corresponding MD simulation on deformation and fracture behavior was investigated to derive a parameterized traction-separation (T-S) law, and then it was embedded into cohesive elements of finite element software. Thus, the crack propagation behavior in NiTi alloys was reproduced by the finite element method (FEM). The experimental results show that the predicted initiation fracture toughness is in good agreement with experimental data. In addition, it is found that the dynamics initiation fracture toughness increases with decreasing grain size and increasing loading velocity.

The effects of styrene-butadiene-styrene (SBS) pre-swelling/extraction process and the incorporation of C9 petroleum resin on the anti-aging performance of modified asphalt were systematically evaluated by characterizing the physical indexes, chemical compositions and rheological parameters. The experimental results show that the SBS pre-swelling/extraction process and the incorporation of C9 petroleum resin improve the dispersion performance of SBS in asphalt as well as the strength of SBS polymer network structures, and the synergistic effects decrease the volatilization degree of asphalt lightweight components and the degradation rate of SBS during the aging process. The anti-aging performance of SBS modified asphalt (SBSMA) was significantly enhanced by SBS pre-swelling/extraction process compounded with the incorporation of C9 petroleum resin, and the anti-aging effect was gradually enhanced with the increase of C9 petroleum resin content.

High molecular weight poly(1,4-butylene 2,5-furandicarboxylate-co-isosorbide 2,5-furandicarboxylate) copolyesters (PBSIF-x) were synthesized via melt-polycondensation of 2,5-furandicarboxylic acid (FDCA), with varying ratios of isosorbide (ISB) and 1,4-butylene glycol (BDO) catalyzed by antimony trioxide (Sb₂O₃). The PBSIF-x structures were investigated using FTIR and ¹H NMR, while the GPC analysis exhibited the copolyesters molecular weights with number average molecular mass (M _n) in the range of 11 079–15 153 g/mol. The DSC results show that PBSIF-x copolyesters have a single glass-transition temperature (T _g) (77.45–110.96 °C), increasing with the increase in ISB content, while TGA analysis demonstrates excellent thermal stability up to 320 °C. From the thermal result, properties of PBSIF-x copolyesters are found to be within the interval of their parent homologues poly(butylene 2,5-furandicarboxylate) (PBF) and poly(isosorbide 2,5-furandicarboxylate) (PIF), which confirms the aromatic/aliphatic blending within the polymer matrix for enhanced polymer stability and performance.

New stared compounds including norfloxacin fragments were prepared via a multi-step route, which were employed as the target corrosion inhibitors (TCIs) for mild steel in 1 mol/L HCl solution. For comparisons, the linear compounds including a single norfloxacin part employed as the reference corrosion inhibitors (RCIs) were synthesized. The molecular structures of the stared compounds were confirmed. The material simulation calculations suggest the presence of large binding energies of the stared compounds on mild steel surface. The enhanced chemisorption of the stared compounds on mild steel surface was demonstrated, which could be resulted by the chemical complexion of the target stared molecules with iron atoms. The reinforced adsorption of the target compounds on mild steel surface was investigated by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The electrochemical analyses reveal the super protection of the TCIs for mild steel in HCl solution, and the anticorrosion efficiency reaches 96.45% (TCI1, 0.050 mM) and 96.61% (TCI2, 0.010 mM) at 298 K.

CGCS (coal gasification coarse slag) and desert sand composite aggregate replacing river sand for the preparation of concrete (coal gasification coarse slag and desert sand composite fine aggregate concrete, abbreviated as CDFC) were investigated to study the effect of different CGCS dosages, the sand rate of concrete, and the dosage of fly ash (FA) in cementitious material on the mechanical properties of the concrete and the excessive zone at the aggregate interface. The experimental results show that, with the increase of CGCS admixture, the CDFC water-cement ratio decreases, and the strength shows first increase and then decrease; with the increase of concrete sand rate, the CDFC strength shows first increase and then decrease, and with the increase of FA, the CDFC strength shows first increase and then decrease, when the dosage of cementitious material is 360 kg/m³, the composite fine aggregate dosage is 872 kg/m³, and the coarse aggregate dosage is 983 kg/m³, the maximum compressive strength of its CGCS is 47.4 MPa. The microstructures of CGCS and hydration products were analyzed by X-ray fluorescence spectrometry (XRF), X-ray diffraction (XRD), Fourier transform infrared spectrometry (FTIR), and scanning electron microscopy (SEM). It is found that the CDFC as fine aggregate can generate hydration products such as hydrated calcium silicate gel (C-S-H) in the transition zone of the concrete interface, which can greatly improve the weak zones of the concrete, and improve the strength.

In order to avoid the waste of iron caused by the direct use of ferronickel slag (FNS) in building materials, the effects of reduction iron extraction on the physical and chemical properties, cementitious reactivity and hydration reaction characteristics of FNS and ferrum extraction tailing of nickel slag (FETNS) were studied. The experimental results show that the reduction ferrum extraction method changes the mineral phase composition of the waste slag, breaks the Si-O-Si bond, forms the tetrahedral structure of Si-O-NBO or Si-O-2NBO, and increases the content of active components such as Ca, Si, Mg, and Al. Compared with FNS, the 28 d compressive strength of pastes prepared by FETNS increases by 16.12%, 22.57%, 33.13%, 44.26%, and 57.65%, respectively. The degree of hydration reaction of the composite cementitious systems in the FETNS group is higher than that in the FNS group at different ages, and the content of hydration products such as C-S-H gel and ettringite (AFt) is also higher than that in the FNS group. More hydration products can improve the curing ability to Cr and Mn of the composite cementitious systems in the FETNS group, and reduce the leaching value of Cr and Mn.

We examined the enhancing effects of different dosages of product of Centrifugation of Bacterial Liquid (product of CBL) on the performance of slag-fGD gypsum-cement-bentonite-sludge system using MICP technology. We analyzed the multifaceted performance of the solidified sludge from macroscopic and microscopic perspectives. The experimental results reveal that the increase in product of CBL dosage results in positive impacts on the solidified sludge, including higher side compressive strength, lower leachate heavy metal concentration, and improved crack repair rates. At a 0.4% product of CBL doping concentration, the strength of the solidified sludge is enhanced by 26.6% at 3 d, 61.2% at 7 d, and 13.9% at 28 d when compared to the unmodified solidified sludge. After 28 days, the concentrations of Zn and Cu ions reduce by 58% and 18%, respectively, and the crack repair rate is 58.4%. These results demonstrate that the increase in heavy metal concentration in the leachate leads to an increase in the strength of the solidified sludge. The strengthening procedure heavily relies on the mineralisation reaction of Bacillus pasteurii, which produces a substantial amount of CaCO₃ to cement the particles and fill the pores initially. The modified solidifying sludge exhibits a self-repairing effect and an enhanced multifaceted performance as a result of oxygen being restored after crack formation and reactivation of Bacillus pasteurii. Such conditions facilitate the body’s recovery.

In view of the increased focus on “green” and sustainable development and compliance with the national strategy for “carbon peak and carbon neutrality,” this study investigated the effect of replacing cement (0–20%) with limestone powder (stone powder) as a mineral admixture on the micro, meso, and macro properties of mortar. First, the applicability of stone powder was examined based on the physical filling and heat of hydration of stone powder-cement. Second, micro-meso testing methods, such as X-ray diffraction, scanning electron microscopy, thermogravimetry-differential scanning calorimetry, and nuclear magnetic resonance, were utilized to reveal the influencing mechanisms of stone powder on the microstructure of the mortar. Furthermore, the effect of stone powder on the compressive strength and gas permeability of the mortar was analyzed. Additionally, the time-dependent variations in the gas permeability and its functional relationship with the mechanical properties were determined. Finally, the correlation between the compressive strength and gas permeability with respect to the pore size of stone powder-doped mortar was established via gray-correlation analysis. The results show that an appropriate amount of stone powder (5%) can effectively improve the particle gradation, decelerate the release of the heat of hydration, increase the amount of hydration products, and improve the pore structure, thereby increasing the compressive strength and reducing the gas permeability coefficient. The gas permeability of stone powder-doped mortar was found to exhibit good time-dependent characteristics as well as a quadratic linear correlation with the compressive strength. The gray-correlation analysis results indicate that air pores exhibit the highest influence on the compressive strength and that the gas permeability coefficient is most significantly affected by large pores.

Seven sets of concrete containing different mass ratios of nano-SiO₂ (0%–5.0%) and nano-CaCO₃ (0%–1.5%) were designed. A total of 28 concrete cube specimens cured for 7 and 28 days were tested for compressive strength (14 specimens) and split tensile strength (14 specimens), while 7 cylindrical specimens cured for 28 days were tested for impact resistance. The impact resistance of the concrete specimens was quantitatively analyzed by using impact strength (f _a) and wear rate (L _a), and the effect of dual incorporation of nano-SiO₂ and nano-CaCO₃ on the microstructure of concrete was further investigated by XRD and SEM. The experimental results indicate that the incorporation of 5.0% nano-SiO₂ and 1.5% nano-CaCO₃ improves the mechanical properties and impact resistance of concrete most significantly, and the compressive strength, split tensile strength, and impact resistance increase by around 37.80%, 35.31%, and 183.36%, respectively, compared with that of ordinary concrete. At the microscopic level, nano-SiO₂ reacts with C-H in a secondary hydration reaction to increase the number of C-S-H gels, which improves the pore structure in the matrix and favorably enhances the adhesion between aggregate and cement paste in the weakened layer, thus improving the abrasion resistance of concrete.

To guarantee the efficient and high-value reutilization of waste concrete from construction waste, the waste concrete was mechanically ground, and three degrees of fineness recycled concrete powder (RCP) were obtained by different grinding time. By analyzing the particle characteristics of RCP with different fineness, the filling-densification effect of cement-RCP cementitious material system was quantitatively investigated based on Andreasen, Fuller, and Aim-Goff models. In addition, the macroscopic mechanical properties of cement paste mixed with RCP were studied, and the influencing mechanisms of RCP on the microstructure of cement paste was revealed. Macroscopic research results show that the particle fineness of RCP after grinding is smaller than that of cement. When the RCP replaces 0% to 20% cement, the packing density based on the Aim-Goff model increases with the increase of RCP content, whereas the macro-mechanical properties first improve and then degrade with the increase of RCP content. Microscopic results show that at 5% RCP content, beneficial hydration products such as C-S-H and beneficial pore increase in cement-RCP paste; while at >15% content, beneficial products decrease and harmful substances such as Ca(OH)₂ and harmful pore increases. These research findings suggest that the incorporation of RCP can make the cementitious system denser, and the appropriate RCP content can improve the macro- and microscopic properties of cement-based materials.

A new type of magnesium oxychloride cement (MOC) was prepared based on calcined MgO powder from hydromagnesite in Tibet, China, with the addition of MgCl₂, a by-product of potassium extraction from the salt lake. The effect of MgO on the microstructure and properties of magnesium oxychloride cement was investigated under different calcination temperatures and time of hydromagnesite, and the hydration process, pore structure and hydration products of the materials were investigated by isothermal calorimeter, MIP, XRD, and SEM, and the mechanical properties of the materials were examined by compressive strength test. The compressive strength test shows that under the optimal conditions (800 °C-2 h), the compressive strength of MOC is 75.65 MPa for 7 d and 87.98 MPa for 28 d in the indoor environment. The main exothermic period of MOC is delayed by about 10 h compared with that of 500 °C-2 h and extended by about 30 h in the process of MOC preparation, which led to the alleviation of the exothermic concentration phenomenon, and the initial solidification time of the MOC specimens is 5.25 h, and the final solidification time is 11.82 h. The MOC phase maintained in indoor air for 28 d mainly consist of P5 and unreacted MgO, and the P5 in the matrix shows the slat-like shape and fills the gaps in the form of needles and rods, and the total porosity is 18.55%.

The degradation performance of pervious concrete containing TiO₂/LDHs-loaded recycled aggregates for NO gas was analyzed using a gas phase catalytic degradation test device, simulating different environmental conditions such as load, ambient temperature, and illumination intensity, which provides theoretical support for practical engineering. The experimental results indicate that when the ambient temperature is controlled at 25 °C and the illumination intensity is 30 W/m², the sample prepared by soaking recycled aggregates in a 0.8% TiO₂/LDHs suspension exhibits the highest photocatalytic degradation rate for NO gas, reaching 72.54%. Further investigation on the influence of environmental temperature reveals that, at 25 °C, the maximum photocatalytic degradation rate for NO gas is 72.9%. Moreover, at an illumination intensity of 40 W/m², the maximum photocatalytic degradation rate for NO gas is 87.08%. Additionally, after three repeated photocatalytic tests, the sample demonstrates good stability, with a photocatalytic degradation rate of 58%. The nitrogen content in the eluent obtained from soaking the sample was determined to be 0.0022 mol/L, with a recovery rate of 80%. The adsorption experiment demonstrates that the sample exhibits a favorable adsorption effect on nitrate ions, reaching a maximum of 56.8%.

In order to study the effects of the contents of used mortar recycled aggregate (OMRA) and brick recycled aggregate (BRA) on the deformation properties of recycled aggregate concrete (RAC), under uniaxial compression conditions, The RAC of OMRA (0%, 5%, 10%, and 15%) and BRA (0%, 3%, 6%, 9%, 12%, and 15%) were studied. The experimental results show that, under uniaxial compression, the interfacial relationships of RAC containing OMRA and BRA between different materials are more complex, and the failure mechanism is also more complex. The content of OMRA and BRA had significant influence on the deformation behavior of RAC. When the content of OMRA and BRA is high, it is difficult for existing formulas and models to accurately represent the actual value. In this study, the influence of OMRA and BRA content is taken into account, and the existing formulas for calculating concrete deformation are modified, so that these formulas can more accurately calculate the elastic modulus, peak strain and ultimate strain of recycled concrete. The stressstrain formula of Guo concrete fits the stress-strain curve of concrete very well. We modified the formula on the basis of Guo formula to make the formula more suitable for the stress-strain curve of recycled concrete containing old mortar and brick, and the theoretical model proposed has better fitting accuracy. The study provides a valuable reference for nonlinear analysis of recycled aggregate concrete structures under different proportions of OMRA and BRA.

The multi-objective optimization of backfill effect based on response surface methodology and desirability function (RSM-DF) was conducted. Firstly, the test results show that the uniaxial compressive strength (UCS) increases with cement sand ratio (CSR), slurry concentration (SC), and curing age (CA), while flow resistance (FR) increases with SC and backfill flow rate (BFR), and decreases with CSR. Then the regression models of UCS and FR as response values were established through RSM. Multi-factor interaction found that CSR-CA impacted UCS most, while SC-BFR impacted FR most. By introducing the desirability function, the optimal backfill parameters were obtained based on RSM-DF (CSR is 1:6.25, SC is 69%, CA is 11.5 d, and BFR is 90 m³/h), showing close results of Design Expert and high reliability for optimization. For a copper mine in China, RSM-DF optimization will reduce cement consumption by 4 758 t per year, increase tailings consumption by about 6 700 t, and reduce CO₂ emission by about 4 758 t. Thus, RSM-DF provides a new approach for backfill parameters optimization, which has important theoretical and practical values.