Abstract:This study employs phosphorous slag as the main raw material and utilizes a water glass-sodium hydroxide compos-ite activation system to prepare phosphorous slag-based geopolymer cementitious materials.By systematically investigating the influ-ence of Na2O content(4%～7%),phosphorous slag powder dosage(70%～100%),water-to-binder ratio(0.17～0.23),and silica oxide content(3%～10%)on the mechanical properties of the material,combined with microstructural characterization techniques such as XRD and FTIR,the phase composition and structural morphology of the hardened matrix were elucidated.The experimental results indicate that when the silica oxide content is≤10%,the strength at various curing ages exhibits a positive correlation with the silica oxide content.Under the optimal mix ratio of m(phosphorous slag):m(fly ash)=9:1,with a Na2O content of 6%,a silica oxide coutent of 10%and a water-to-binder ratio of 0.17,the 28-day compressive strength reaches 73.9 MPa.Mechanism analysis reveals that silica enhances the compactness of the system through the pozzolanic reaction and the micro-aggregate filling effect,thereby improving the later-stage mechanical properties of the material.

Abstract:Metal corrosion is a major safety hazard threatening key fields such as energy,transportation and marine engineering.Traditional anti-corrosion coatings are difficult to meet the long-term protection requirements under harsh working conditions.Graphene,with its unique two-dimensional sheet structure and excellent physical and chemical properties,provides a new idea for the development of high-performance anti-corrosion coatings.This paper reviews the research on the improvement and optimization of the corrosion resistance of graphene anti-corrosion coatings from the aspects of the dispersion of graphene in the coating,the directional arrangement of graphene in the coating,the adhesion strength between the coating and the substrate,and the modification of catalytic passivation films.It also discusses the contradictions and problems faced when achieving stable dispersion of graphene in anti-corrosion coatings,and proposes the research and development direction of functional integration and intelligent response of graphene anti-corrosion coatings.

Abstract:This paper proposes to use polyaluminium chloride(PAC)as a new inhibitor and systematically studies its inhibito-ry effect on alkali efflorescence in cement mortar.The mechanism of action of PAC was revealed through characterization methods such as X-ray diffraction(XRD),scanning electron microscopy(SEM),energy dispersive X-ray spectroscopy(EDS),and thermogravi-metric analysis(TG).The results show that the addition of 5.0%PAC can significantly inhibit alkali efflorescence in cement mortar and maintain the stability of its apparent color for a long time.PAC reduces the alkalinity of the system and introduces Cl-by consuming Ca(OH)2 generated in the early stage of hydration,promoting the conversion of ettringite(AFt)into Friedel salt,thereby reducing the migration of free Ca2+and inhibiting alkali efforescence.In addition,PAC can promote the hydration reaction of trical-cium silicate(C3S)and dicalcium silicate(C2S),optimize the microstructure,and enhance the later compressive strength of mortar.

Abstract:The effect of fiber type and content on flexural toughness and deformation resistance of Formwork shell concrete(FSC)was studied when steel fiber(SF)was used alone or in combination with polypropylene(PP)fiber and polyvinyl alcohol(PVA)fiber.The hybrid and toughening effects of SF and organic fiber were analyzed.The results show that the effect of organic fiber with high content(0.50%)SF on the toughness and deformation resistance of FSC is better than that of mixing with low content(0.30%)SF.The flexural toughness of FSC was significantly improved by SF-PP fiber hybrid,while the deformation resistance of FSC was significantly improved by SF-PVA fiber hybrid.The optimal bending strength of FSC with SF-PP fiber hybrid at 7 days and 28 days can achieve 8.9 MPa and 11.8 MPa,which is 21.9%and 9.3%higher than that of single SF.The optimal elastic modulus of FSC with SF-PVA fiber hybrid at 7 days and 28 days can achieve 20.9 GPa and 41.2 GPa,which is 13.6%and 13.2%higher than that of single SF,respectively.

Abstract:This study prepared foam concrete by partially replacing cement with steel slag sand and incorporating bentonite slurry.The mechanisms through which these components affect the compressive strength were elucidated via compressive strength tests and SEM analysis.The results indicated that an appropriate amount of steel slag sand promotes the formation of hydration products,improves slurry fluidity and foam distribution,while the unhydrated steel slag acts as a skeletal support,collectively en-hancing the strength.Bentonite slurry increases strength by adsorbing free water and filling microcracks,thereby densifying the pore structure.Under synergistic interaction,the hydration products from steel slag and the bentonite exhibited a complementary filling effect,significantly reducing porosity.The enhancement in compressive strength was greater in this synergistic system than in sys-tems containing only steel slag or bentonite.However,excessive steel slag sand inhibits hydration and increases structural hetero-geneity,while excessive bentonite slurry raises free water content,leading to pore coarsening,structural loosening,and agglomeration,both of which degrade mechanical properties.Based on the trends in compressive strength,the optimal mix proportion was deter-mined as a 10%replacement rate of steel slag and a 5%dosage of bentonite slurry.

Abstract:In this study,microbially induced calcium carbonate precipitation(MICP)was employed to improve the engineering performance of expansive soil from Nanyang.The effects of varying bacterial concentrations,cementation solution concentrations,and curing durations on the soil's expansion behavior were systematically investigated.The results demonstrate that the application of Sporosarcina pasteurii effectively suppresses the expansion characteristics of expansive soil.The inhibition effect of MICP on soil expansion mainly occurs when the curing time is 7th to the 21st day,with minimal changes observed during both the early curing stage(day 1～7)and the later stage(days 21～28).The expansion ratio notably decreases as the bacterial concentration increases.Specifically,within the range of OD600=0.～1.0,a significant reduction in expansion rate is observed,whereas the rate of reduction di-minishes between OD600=1.0～2.0,with the minimum expansion observed at OD600=2.0.Similarly,increasing the cementation solution concentration from 0 to 1.0 mol/L markedly reduces the expansion rate,but further increases from 1.0 to 1.5 mol/L yield diminishing returns.Beyond 1.5 mol/L,the expansion rate is slightly increased.

Abstract:In order to improve the road performance of cement-based solidified soil,the compressive strength,dry shrinkage performance,and density variation of cement-based solidified soil with different cement contents and mixing processes were compared and analyzed through experiments.The experimental results show that under four different cement dosages of 4%,6%,8%,and 10%,compared with ordinary mixing,the 7 d and 28 d compressive strength of solidified soil under vibration mixing increased by 6.0%and 5.9%,respectively.The dry shrinkage strain of solidified soil at each age under vibration mixing is lower than that of ordinary mixing,and the dry shrinkage strain at 14 days of age under vibration mixing decreased by 3.2%.The average mass of cement stabilized soil with vibration mixing at various ratios increased by 4.7%compared to ordinary cement stabilized soil.The research results indicate that vibration mixing improves mixing efficiency and can enhance the performance of solidified soil,providing reference for the engineering application of solidified soil.

Abstract:This study proposes the implementation of air pressure balance hole in the intermediate thin glass layer to optimize its mechanical behavior under wind loads.Finite element analysis was employed to investigate the influence patterns of these pres-sure balance holes on the displacement,stress,and cavity thickness variations in thin-chamber insulating glazing(TC-IG).The re-sults indicate that 1 mm diameter pressure balance holes effectively reduce both the maximum displacement of the middle glass and the principal stress at glass center under wind loads,with the reduction magnitude increasing proportionally to wind load in-tensity.As the thickness of the middle glass decreases,the displacement reduction initially diminishes then increases,while the principal stress reduction shows gradual enhancement.Thinning of both outer and inner glass leads to progressive increases in dis-placement and principal stress reductions of the intermediate layer.Notably,under high wind load conditions of 5 kPa,contact phe-nomena occur between outer and middle glass when the outer and inner glass are relatively thin compared to the middle glass,re-sulting in stress concentration at the contact position near the panel center.

Abstract:In order to study the influence of alkaline building materials such as cement and mortar on the properties of aero-gels,an accelerated aging test with a concentration of 5%NaOH solution was designed,and the effects of alkaline environment on the morphology,bending properties,compressibility and vibration mass loss of silicon-based aerogels were analyzed.The results show that with the increase of soaking time,the hardness of the re-dried aerogel plate gradually decreases,and the physical and mechan-ical properties decrease sharply;When soaked for 14 days,the flexural bearing capacity,compressive strength and compressive modu-lus decrease by 92%,92%and 94%respectively;When soaked for 28 days,the flexural ability is basically lost,and the retention rate of compressive strength and compressive modulus is only 3%～5%;The vibration mass loss rate of the aerogel plate increases first and then decreases with the increase of soaking time,and the loss rate reaches the highest value of 7.00%after soaking for 14 days.Later,the loss rate gradually decreases to 1.88%due to the crystals of NaOH solution precipitating and adhering to the surface of the aerogel plate.

Abstract:To reduce the use of petroleum-based softeners,a synthetic bio-additive based on biomass oil was developed.After adding the synthetic bio-additive to aged asphalt for regeneration,in the four-component test of asphalt,the polar components mi-grated,and the actual content of asphaltenes decreased by 41.7%compared to the theoretical value,while the actual content of sat-urates increased by 37.5%compared to the theoretical value.The waterproof modified asphalt coating material test showed that when the synthetic bio-additive was synthesized with a mass ratio of cashew nut shell oil to waste cooking oil of 5:5,compared with the same dosage of waste engine oil,the low-temperature flexibility of the waterproof modified asphalt decreased by 1℃,the low-temperature flexibility decline after thermal aging reduced by 25%,and the joint peel strength increased by 0.2 N/mm.Under the same cost-effectiveness,the addition amount of softeners was reduced by 1 percentage point,thereby reducing the cost of wa-terproof materials.The synthetic bio-additive has an activation effect on rubber powder,making the segregation of the system re-duce greatly,thereby improving the thermal stability of the modified asphalt coating material.

Abstract:A high-performance waterborne asphalt anti-corrosion coating was successfully prepared using acrylic emulsion and anionic emulsified asphalt as the primary film-forming substances,with the incorporation of appropriate functional additives and fillers.This study investigated the effects of factors such as the content of the aqueous emulsion modifier and the type of metal surface treatment agents on the coating film properties,explored the mechanism of action of different metal surface treatment agents.The experimental results demonstrated that as the content of the aqueous emulsion modifier increased,the rigidity and hardness of the coating film improved.However,excessive content resulted in material embrittlement.With the formulation containing 6%aque-ous emulsion modifier and 2%organic polymer chelating agent D,the coating film achieved a tensile strength of 1.27 MPa and a pencil hardness of 2H.This formulation exhibited excellent anti-corrosion performance,with no flash rust observed on the wet film for 10 days.Its primary mechanism of action is physical barrier.

Abstract:To study the flexural performance of light steel keel sheathing,five wall panel specimens were designed and sub-jected to a four-point concentrated loading test.The test results show that the light steel keel sheathing has good flexural perfor-mance;increasing the wall thickness and web height of the light steel keel are the main factors to improve the flexural performance of the wall panel.Excessively large spacing of self-tapping screws weakens the composite effect between the sheathing and the light steel keel,thereby reducing the flexural performance of the wall panel.The theoretical calculation of the flexural capacity of the wall panel was carried out based on the superposition principle,and corrected by combining the strength reduction factor of the fiber cement board.The corrected theoretical values are in good agreement with the test values.

Abstract:Based on the measured data of mortar linear expansion rate under different temperatures and magnesia content,a hyperbolic prediction model of mortar linear expansion rate under temperatures was established.The chemical reaction kinetics the-ory and model fitting regression analysis were used to determine the reaction rate constant and the final linear expansion rate of mortar specimens,and the relationship between the reaction rate constant and temperature was established by Arrhenius equation,and the equivalent time was deduced by using the maturity function.Finally,the study established the prediction of linear expan-sion rate of mortar with magnesia expansive source at room temperature by rapid curing method,and verified the feasibility and accuracy of the prediction model.It can provide reference for the prediction of linear expansion rate of mortar with magnesia ex-pansive source in practical engineering,and also provide technical support for evaluating the potential hazard degree of magnesia on the volume of mortar.

Abstract:A novel environment-friendly grouting material was prepared using silane-modified polymer resin as the main raw material,incorporating plasticizers,fillers,and various additives.The key factors affecting the performance of grouting material,such as the types of silane modified polymers,the mass ratio of fillers to plasticizers,and the dosage of silane coupling agents,were dis-cussed in detail.The results indicate that the optimal performance was achieved with a dosage of silane-modified polymer A at 20%～25%,a filler-to-plasticizer mass ratio of 2.5:1.0,and a silane coupling agent content of 1.0%～1.5%.Under these conditions,the prepared grouting material exhibited a tensile strength of 1.80 MPa,an elongation at break of 530%,a dry substrate bonding strength of 1.10 MPa,a wet substrate bonding strength of 0.74 MPa,a tensile modulus as low as 0.33 MPa,an elastic recovery rate of 92%,and a viscosity of 15000 mPa·s.

Abstract:By testing the compressive strength,hardness,pH value,chemically bound water content,hydration products,and mi-croscopic morphology of concrete at different depths after fire exposure,the effects of fire on the mechanical properties,hydration pro-cess,and microstructure of concrete were analyzed.The results showed that the strength loss of concrete after fire gradually decreased with increasing depth.The greatest strength loss occurred in the surface layer,with its strength reduced to 38%of that of normal concrete.After the depth exceeds 50 mm,the loss of compressive strength is significantly reduced.The microhardness of the surface layer was approximately 61%of that of normal concrete.After fire exposure,the pH value of concrete was slightly lower than that of normal concrete,with minimal differences observed across depths.The chemically bound water content increased with depth,remaining comparable to that of normal concrete within 150 mm from the surface.The hydration products of cement paste at different depths showed little variation,primarily consisting of dolomite and tobermorite.SEM characterization revealed that the surface layer of con-crete had low density,with numerous cracks and pores.

Abstract:This study focuses on graphene oxide(GO)modified asphalt and 70#virgin asphalt as the research object,adopting the dynamic shear rheometer(DSR)to conduct frequency sweep tests,linear amplitude sweep(LAS)tests,and self-healing tests,aim-ing to reveal the variation patterns of fatigue self-healing properties of GO modified asphalt under various aging conditions.The re-sults indicate that GO can,to a certain extent,enhance the fatigue properties and self-healing properties of 70#virgin asphalt.Short-term and long-term aging processes improve the fatigue performance of both asphalts.Short-term UV exposure strengthens the fatigue performance of GO modified asphalt subjected to short-term and long-term aging,but prolonged UV exposure exerts detrimental effects.As the degree of aging intensifies,the self-healing properties of both GO modified asphalt and 70#virgin as-phalt gradually decline,and UV radiation further exacerbates this decline in self-healing capabilities.

Abstract:The causes and influencing factors of the volume expansion of steel slag were analyzed,and the methods for stabi-lizing the volume expansion of steel slag were summarized.The research progress and characteristics of different treatment methods were discussed,and future directions and suggestions for further exploration were proposed.The research results indicate that free calcium oxide(f-CaO)and free magnesium oxide(f-MgO)in steel slag are the main causes of the volume expansion of steel slag;The process,melting and tempering,and aging treatment can significantly reduce the content of active substances in steel slag,with a reduction rate of up to 60%to 90%.Carbonization treatment,acidification treatment,and the addition of mineral materials can ef-fectively eliminate active substances such as f-CaO in steel slag,and the reduction rate of volume expansion of processed steel slag can reach over 80%;The surface modification treatment method is simple and has a short cycle,but the treatment effect is rela-tively weak,and there is still a risk of modifier detachment in the later stage,causing the volume expansion of steel slag;Long term monitoring of various properties of processed steel slag mixture,development of unified comprehensive treatment technology for steel slag volume stabilization,and strengthening the uniformity of carbonization inside and outside steel slag aggregates can be used as future research directions for steel slag volume stabilization treatment.

Abstract:An early strength polycarboxylate superplasticizer suitable for non-steam conditioned sleeper concrete was developed to solve the problem of low formwork turnover rate caused by insufficient strength of precast concrete in the early stage,while en-suring the workability and durability of concrete.Through orthogonal test,the basic process parameters were determined,and seven different monomers were selected to synthesize the mother liquor.The results showed that the basic synthesis process parameters were as follows:molar ratio of initiator to polyether monomer was 0.35,molar ratio of hydrogen peroxide to ascorbic acid was 5,mo-lar ratio of chain transfer agent to polyether monomer was 0.2,reaction temperature was 50℃,and when 0.23%of the superplasti-cizer synthesized using quaternary ammonium cationic methylacryloyloxyethyl trimethyl ammonium chloride was added,the 1-day,3-day,and 7-day compressive strengths of the concrete were 33.1 MPa,48.0 MPa,and 58.9 MPa,respectively;when 0.23%of the su-perplasticizer synthesized using N,N'-dimethylacrylamide with amide groups was added,the 1-day,3-day,and 7-day compressive strengths of the concrete were 30.6 MPa,47.6 MPa,and 58.5 MPa,respectively.

Abstract:This study proposes a synergistic crack control technology using moderate heat cement,three-graded concrete,and an-ti-cracking agent.By comparing the hydration heat characteristics of moderate heat cement and ordinary cement,and adding 6%to 10%anti-cracking agent,the mechanical properties,deformation characteristics,and adiabatic temperature rise of concrete were system-atically tested.The results show that the synergistic effect of the three significantly reduces the rate of hydration heat release.With 10%anti-cracking agent addition,the hydration heat release rate of the cement paste decreased by approximately 33.3%,and the adi-abatic temperature rise of concrete decreased by about 2.3℃.Additionally,the autogenous volume deformation of concrete shifted to expansion,reaching approximately 230 με at 28 days with 10%anti-cracking agent,without adversely affecting the mechanical prop-erties.Application monitoring in a practical engineering project revealed that the central deformation of concrete remained expansive during the cooling phase,and no cracks were observed during the service period.

Abstract:Different aqueous silica aerogel slurries were prepared via modification using the physical method of polyvinyl alco-hol(PVA)and the chemical method of KH550.Systematic characterizations of the two types of slurries and their dry powders were conducted by means of specific surface area and porosity analysis,thermal conductivity analyzer,contact angle tester,etc.The results showed that the performance of the aerogel slurry prepared by the PVA physical modification method was superior to that prepared by the KH550 chemical modification method.Specifically,the 5%PVA physically modified aerogel slurry,after drying,exhibited a room-temperature thermal conductivity of 0.0253 W/(m·K),a contact angle of 128.2°,a specific surface area of 598 m2/g,a pore volume of 2.6 cm3/g,and an average pore size of 19.5 nm,which well retained the nanoporous structure of the aerogel.Meanwhile,the composite EPS thermal insulation and non-combustible board with a 10%SiO2 aerogel content was prepared,which had a ther-mal conductivity of 0.048 W/(m·K).Additionally,the composite water-based thermal insulation coating with a 25%SiO2 aerogel content showed a thermal conductivity of 0.035 W/(m·K).This study provides new material solutions and technical approaches for the development of multifunctional and high-performance building thermal insulation systems.