Abstract:This paper studied the influence law of the composition and replacement ratio of heavy metal sludge sintered slag on the durability,and resistance to chloride ion penetration and sulfate attack of ultra-high strength concrete(UHSC).Its mechanisms were further investigated through microstructural analysis techniques such as XRD,SEM,and X-CT.The results indicated that as the replacement ratio of sintered slag increased,the chloride ion penetration resistance of UHSC first improved and then declined,with the optimal erosion resistance observed at an aggregate replacement ratio of approximately 20%.Additionally,coarse-grade residue further inhibited chloride ion diffusion by reducing the number of interfacial transition zones(ITZs)between the paste and aggregate,thereby enhancing the compressive strength of the high-strength matrix.Microstructural analysis revealed that the sintered residue significantly improved the sulfate erosion resistance of UHSC by refining the pore structure,effectively suppressing ettringite-induced expansion damage.

Abstract:Through rapid compatibility tests of concrete admixtures and mortar bleeding rate tests,the adaptability of polycar-boxylate superplasticizer(PCE)with different types of polyether macromonomer,acid-ether ratio and chain transfer agent dosage,on the water-washed machine-made system was systematically analyzed.Cationic functional monomer C005 and crosslinking monomer C006 were introduced for modification.The results showed that when TPEG was selected as the monomer,the acid ether ratio was controlled at 3.50～3.75,and the amount of chain transfer agent mercaptopropionic acid was 0.4%～0.5%of the total monomer mass,the synthesized PCE had better adaptability to washed machine-made sand concrete.On this basis,DJ-410 water reducing agent was prepared by modifying monomers C005 and C006.Compared with the ordinary water reducing agent DJ-100,the bleeding rate of concrete mixed with DJ-410 decreased from 4.3%to 0.8%.The compressive strength increased by 5.4%after 28 days,indicating better adaptability.

Abstract:Viscosity-reducing polycarboxylate superplasticizer was synthesized using polyether macromonome,acrylic acid(AA),methacrylic acid(MAA),and mercaptopropionic acid(MPA)as the main raw materials,and hydrogen peroxide-E51 as Redox initia-tion system.The effects of molecular mass and structure of polyether macromonome(Such as EPEG3000,EPEG1200,TPEG1200 and so on),acid-ether ratio,MPA dosage,and MAA percentage on the properties of synthetic water reducing agents were investigated.The results indicate that under the reaction temperature of 10～15℃,when n(EPEG1200)∶n(EPEG3000)=2.0,with an acid-to-ether ratio of 3.6,MPA accounting for 0.4%of the macromonomer mass,and n(MAA)∶n(AA)=2.0,the synthesized viscosity-reducing poly-carboxylate superplasticizer JN-2405 exhibited optimal performance.When applied to high-performance concrete,it demonstrated more pronounced viscosity-reducing effects at lower dosages compared to the commercially available viscosity-reducing polycarboxy-late superplasticizer JN-1.

Abstract:Using reed straw as raw material,porous biochar matrix was prepared via high-temperature carbonization,and vacu-um melt impregnation combined with expanded graphite(EG)modification was employed to fabricate the composite.Experimental results show that the optimal PCM content is 65%by mass,achieving minimal leakage.The composite exhibits an enthalpy of 169.1 J/g and a thermal conductivity of 1.14 W/(m·K),representing a 612.5%improvement compared to pure PCM.No chemical reactions exist between components,indicating excellent compatibility.Thermal cycling tests demonstrate a 28%reduction in super-cooling and enhanced thermal stability.Practical application tests show that the melting and setting time of this material is short-ened by 62%and 61%respectively compared to pure PCM.The prepared composite PCM has low cost and high performance,showing promising potential in building energy efficiency,solar thermal storage,and other fields.

Abstract:To address issues such as cracking,spalling,leakage,and durability in exterior wall protective mortar layers,one-part component polymer anti-crack and waterproof plastering mortar has been developed.An orthogonal experiment was conducted to in-vestigate the effects of cement,polymer powder,cellulose ether,and water-reducing agent on mortar properties.The results show that cement significantly influences the waterproofing,crack-resistance,and bonding properties of mortar;cellulose ether facilitates the improvement of mortar workability and toughness;and water-reducing agents are the key components for achieving high strength,high durability,and low porosity.The one-part component polymer cement mortar prepared based on the optimized formulation ex-hibits outstanding performance.The mortar exhibits a 2-hour consistency loss rate of 14.2%,water retention rate of 99.91%,bonding strength with cement mortar is 1.07 MPa,bonding strength with thermal insulation substrate is 0.35 MPa,compressive-to-flexural strength ratio is 2.6,water absorption rate is 2.7%,and water resistance pressure reaches 1.6 MPa.

Abstract:This study investigates the effects of base asphalt,oil additives,crumb rubber,ST modifier,8903 plasticizer,and fillers on the properties of modified asphalt,aimed at optimizing product performance.The results indicate that the addition of oil additives does not significantly improve the low-temperature flexibility of modified asphalt but markedly reduces the seam peel strength,with a substantial loss in aging performance.After modification with 40%crumb rubber,the softening point of the base asphalt increases by 17～66℃,and the viscosity of the modified asphalt also varies significantly.The addition of the ST modifier enhances the softening point and seam peel strength of the asphalt while improving its low-temperature flexibility.With the addi-tion of the 8903 plasticizer,the softening point of the modified asphalt increases notably,though low-temperature flexibility slightly deteriorates,penetration decreases,and seam peel strength improves.As the filler content increases,the softening point and viscosity of the modified asphalt gradually rise,while low-temperature performance and seam peel strength decline.

Abstract:This study employs finite element simulation to establish numerical models of ultra-low energy consumption thin-walled exterior wall panels and shear wall exterior panels.The mechanical performance of both panels under combined single-sided heating and wind loads was investigated.Results demonstrate that thin-walled panels exhibit greater susceptibility to temperature differences.The initial stiffness of wall panels shows a negative correlation with temperature differences caused by single-sided heating.Specifically,as the temperature difference increases from 10℃to 40℃,the initial stiffness decreases by approximately 61.47%-82.84%.Under identical temperature conditions,reducing the sandwich insulation layer thickness from 100 mm to 50 mm leads to a 41.85%reduction in initial stiffness and performance degradation.Changing the connector spacing from 500 mm to 300 mm does not significantly impact mechanical performance.

Abstract:In this paper,dry desulfurization ash is selected as the main raw material to prepare dry desulfurization ash-based cementitious materials.The orthogonal experimental design was used to investigate its optimal mix ratio and evaluate its application in cured silt.The results show that:when the slag powder/dry desulfurization ash is 2:1,with 3％lime dosage,15％cement,9％desulfurization gypsum,and using LCA as exciter,the 28 d compressive strength of the cementitious material is 41.25 MPa,and the main hydration products are AFt,C-S-H gel,AFm and so on.The strength of the cured sludge is better than adding the lime when using the cementitious materials,which can satisfy the strength requirements for the base layer of secondary and lower sec-ondary roads in the"Technical Rules for Construction of Highway Pavement Base Layer"JTG/T F20-2015.

Abstract:A prefabricated non-removable thermal-insulated bottom formwork steel reinforcement cage floor deck was prepared by using thermal-insulated non-removable bottom formwork and steel reinforcement cage connected via fasteners.Finite element analysis was conducted on its stress performance during the hoisting,construction,and service stages.Experimental research was conducted on the stress performance during the construction stage,and its insulation performance was tested and calculated.Results show that the bearing capacity,deformation,and cracks of the floor bearing plate during the hoisting,construction,and service stages all meet the requirements specified in codes such as Technical Specification for Application of Steel Truss Floor Bearing Plates(T/CECS 1069-2022).The non-removable thermal-insulated bottom formwork exhibits excellent thermal insulation performance,and the number of supports required during the construction stage is significantly reduced.The prefabricated floor deck designed in this study can realize the integration of thermal insulation and formwork,eliminate the on-site processes of steel mesh binding and ther-mal insulation layer construction,and thus greatly improve construction efficiency.

Abstract:Based on lightweight aggregate concrete(LAC)with 0.1%polyester fiber(PET),the effects of steel fiber(SF),carbon fiber(CF)and basalt fiber(BF)on the working performance,dry apparent density and mechanical properties of LAC are studied,and the optimal type and content of composite fiber are determined.In this paper,the best fiber reinforced lightweight aggregate concrete is used as the bottom plate of the steel truss bearing plate,and the bearing capacity test is carried out.The results show that the LAC with 0.8%steel fiber and 0.1%polyester fiber has the best compressive strength,flexural strength and tensile strength,which are 34.0 MPa,4.39 MPa and 6.80 MPa respectively and the ratio of compression to bending and the ratio of compression to tension are the smallest,which greatly improves the bending resistance of LAC.The optimal fiber lightweight aggregate concrete reinforced truss bearing plate has high bearing capacity and small crack width under ultimate load.

Abstract:This study developed a CO2 sequestered fiber cement flat sheets using steel slag and pulp fiber as primary raw materials via carbonation curing.The influence of forming pressure,cement content,pulp fiber content,and water-solid ratio on its properties was investigated.The results demonstrated that under a forming pressure of 25 MPa,the CO2 sequestered fiber cement flat sheets achieved optimal CO2 uptake and water-saturated flexural strength.The results of the orthogonal experiment showed that the most critical influencing factors on CO2 absorption,saturated flexural strength,and water absorption were cement content,water to solid ratio,and pulp fiber content,respectively.The calcium carbonate generated from carbonation curing filled pores in the fiber cement flat sheets and strengthening interfacial bonding between pulp fibers and matrix.Additionally,carbonation curing consumed free calcium oxide in steel slag,effectively resolving the volume stability issues associated with steel slag.

Abstract:Although microwave curing enhance early-age performance,it often compromises long-term properties.To address this limitation,this study proposes an optimized strategy involving the incorporation of porous aggregates(Zeolite sand)into the cementi-tious matrix to study the optimization effect of microwave curing and zeolite sand on the performance of ultra-low water/binder ratio concrete,and analyze the influencing mechanism through isothermal calorimetry and low-field nuclear magnetic resonance.Results demonstrated that,following 4 minutes of microwave pre-curing,the 7 d compressive strength of the zeolite-modified group increased by 14.5%compared to the control group.The addition of zeolite sand prolonged the induction period while accelerating the subse-quent acceleration phase of hydration.Furthermore,its porous structure contributed positively to later-stage hydration.During mi-crowave curing,zeolite sand provides space for storing high-energy water in the matrix,thereby mitigating rapid energy input during microwave curing and allowing for preparation for later-stage hydration.

Abstract:This study investigates the effects of nickel-zinc ferrite and graphite as wave-absorbing agents on the mechanical(compressive and splitting tensile strength)and wave absorbing properties of concrete.Results indicate that compared to that not mixed,when the dosage of nickel-zinc ferrite is 3.0%,the compressive strength and splitting tensile strength increase by 6.5%and 11.9%,respectively,while the wave absorption performance is significantly enhanced,with a minimum reflection is-16 dB at 2.5 GHz,particularly effective in the high-frequency range.However,exceeding this dosage leads to a gradual decline in both properties.In con-trast,the addition of graphite,despite improving wave absorption,causes a severe deterioration in mechanical performance.Microstruc-tural analysis reveals that nickel-zinc ferrite can optimize pore structure,whereas the flaky structure of graphite creates weak interfa-cial areas,deposite C-S-H gel,affects the structural continuity and compactness,leading to the reduction of mechanical properties.It is recommended that the dosage of nickel-zinc ferrite should not exceed 3.0%,and graphite should be limited to 1.5%to balance strength requirements with wave-absorbing efficiency.

Abstract:Using copper tailings as the main siliceous raw material,and adding cement,quicklime,gypsum,and using aluminum powder as an air entraining agent to prepare autoclaved aerated concrete products.The effects of siliceous material mix proportion,autoclaving system,and water to material ratio on the properties of autoclaved aerated concrete blocks are studied.Research indi-cates that fine copper tailings exert significantly greater negative impacts on copper tailings aerated products compared to coarse copper tailings,under the condition without river sand addition,the mixing amount of fine tailings should be restricted to 40%;Au-toclaved pressure is recommended to exceed 1.1 MPa,with the water-to-material ratio maintained between 0.65～0.70.Under these parameters,its compressive strength is 4.25～4.65 MPa,dry density remains below 605.6～610.5 kg/m3,meet the standard requirements of A3.5 B06.The compressive strength of copper tailings aerated concrete products are mainly influenced by the tobermorite,hy-drogarnet and C-S-H(I)gel produced by SiO2 and Ca(OH)2,cement hydration products and the pore structure formed by gas,an optimized autoclaved system promotes enhanced tobermorite crystallization while refining the pore structure,this synergistic effect ul-timately improves the comprehensive performance of the aerated products.

Abstract:To address the issues of low reactivity and low resource utilization efficiency of steel slag,while overcoming the high cost associated with traditional chemical activators,this study employs low-cost solid waste as an activator.It specifically in-vestigates the effects of three types of desulfurization gypsum(dihydrate gypsum,hemihydrate gypsum,and anhydrite)on the hydra-tion behavior of a steel slag-cement system.The investigation included tests of compressive strength,setting time,compatibility with admixtures,and rheological properties,supplemented by microstructural analysis using XRD and TG-DSC.The results demonstrate that all three gypsum types significantly enhance the compressive strength of the steel slag-cement system.The 28-day activity in-dices were 90%for dihydrate gypsum,89%for anhydrite,and 86%for hemihydrate gypsum.Furthermore,the gypsums extended the setting time,improved compatibility with the superplasticizer,and reduced the system's viscosity and thixotropy.The underlying mechanism involves the SO42-ions released by the dissolution of gypsum reacting with Al3+and Ca2+ions in the system to form et-tringite(AFt),which accelerates the hydration process and consequently improves the performance of the steel slag-cement system.

Abstract:By establishing a refined finite element model of the anti-icing asphalt pavement,the influence laws of the incor-poration of slow-release anti-icing materials on the key mechanical responses(vertical displacement,bottom stress and strain)of the pavement structure and typical failure modes(crack propagation,rutting deformation)were studied.The results show that the incor-poration of anti-icing materials leads to an increase of about 0.001～0.008 mm in the vertical displacement of the asphalt surface layer under load.The incorporation of anti-icing materials has an adverse effect on the opening type cracks at the bottom of the pavement surface layer,and the stress intensity factor at the crack tip can increase by up to 3555.5 Pa·m1/2 under the influence of anti-icing materials.The incorporation of anti-icing materials has no obvious adverse effect on the rutting of asphalt pavement.In the structural design process of salt storage type anti-icing asphalt pavement,the asphalt surface layer can be considered to be thinned.

Abstract:The effects of the dosage of municipal solid waste incineration fly ash slag(referred to as fly ash slag)on the mechanical properties,leaching toxicity characteristics,and durability of cement-based composites were studied,and microscopic testing methods such as SEM,XRD,and TG were employed to abalyze their reaction mechanisms.The results indicate that the un-confined compressive strength of cement-based materials generally decreases with increasing fly ash slag content,with minimal im-pact when the content is below 20%.When the fly ash slag content exceeds 10%,the unconfined compressive strength significantly decreases after 40 freeze-thaw cycles.After 31 wet-dry cycles,the unconfined compressive strength remains higher than that of the pure cement group.The heavy metal leaching concentrations of cement-based materials with 50%fly ash slag incorporation meet the requirements of GB 5085.3-2007"Standard for Identification of Hazardous Waste:Leaching Toxicity Test"for both 7-day and 90-day samples.

Abstract:In this study,low-carbon cementitious materials were used to coat and strengthen the recycled aggregates from waste concrete and clay bricks,and the influence law and mechanism of the proportion of strengthened recycled aggregates replac-ing natural aggregates on the mechanical properties and freeze-thaw cycles of pavement base materials were explored.The results show that a dense hydration product is formed on the surface of the reinforced recycled aggregate,compensating for the performance defects of the recycled aggregate.The use of reinforced recycled aggregates can reduce the optimum moisture content of inorganic mixtures and increase the maximum dry density.Meanwhile,the unconfined compressive strength and frost resistance of inorganic mixtures were improved.The 7-day unconfined compressive strengths of the recycled aggregates of reinforced waste concrete and reinforced waste clay bricks were 5.98 MPa and 4.84 MPa respectively,and the residual compressive strength ratios after 5 freeze-thaw cycles could reach 86%and 77%respectively.

Abstract:Concrete with different strength grades was designed by changing the type and content of mineral admixtures,and the effect of the addition of sulfate-resistant and corrosion-inhibiting admixtures on the durability of concrete was studied.The results show that the durability of concrete is closely related to the design of mix proportion,mineral admixtures and sulfate-resistant and corrosion-inhibiting admixtures,with the order of effectiveness from strong to weak is:adding anti-corrosion and corrosion-inhibiting admixtures>adding admixture>improving strength grade.The incorporation of 5%sulfate-resistant and corrosion-inhibiting admixtures in C35 concrete can achieve the 28 d electric flux and 28 d chloride ion migration coefficient at 810 C and 3.9×10-12 m2/s respective-ly.The corrosion resistance coefficient after 150 sulfate dry-wet cycling is 0.86,and the carbonation depth at 28 days is 4 mm,which meets the excellent durability evaluation standard of concrete specified in JGJ/T 193-2009.

Abstract:In this paper,the effects of silica fume content and age on the compressive strength of high performance self-com-pacting concrete(HPSCC)were investigated through two-factor variance analysis,and a compressive strength prediction model was es-tablished.Studies have shown that both the silica fume content and age have a significant effect on the compressive strength of HP-SCC.The compressive strength of the cube first increases then decreases with the increase of silica fume content and then,the 28 d compressive strength reaches the maximum value when the silica fume content is 13%.The increase of silica fume content has a certain effect on change of early compressive strength,and the 7 d/28 d strength ratio reaches 92.1%when the content is 15%.The HPSCC compressive strength prediction model based on silica fume content and age has been established.