Abstract:The rapid setting time and high heat release of magnesium oxychloride cement(MOC)lead to poor workability dur-ing construction,limiting its engineering applications.The effects of 0,10%,20%,and 30%substitution of magnesium oxide with plant ash on the rheological properties,mechanical properties,and microstructure of MOC were systematically investigated.The flow curves were fitted using the modified Bingham model,and the mechanism was revealed by combining universal testing machines,scanning electron microscopes(SEM),X-ray diffraction instruments(XRD),and comprehensive thermal analyzers(TG).The results show that plant ash significantly improves MOC rheology by reducing yield stress and plastic viscosity via a dilution effect.Howev-er,excessive plant ash suppresses the formation of 518-phase(5MgO·MgCl2·8H2O)and interrupts the continuity of hydration prod-ucts,resulting in a 15.76%decrease in 28-day compressive strength.This research provides reference for the resource utilization of biomass solid waste and the development of low-carbon cementitious materials.

Abstract:To further investigate the influence of calcium phosphate chemical dealkalization method on the planting performance of porous concrete,porous concrete specimens were soaked in 1%,2%,and 3%calcium phosphate and potassium dihydrogen phos-phate solutions,after soaking,high fescue,Manila grass and alfalfa were selected for planting tests.The results shows that the dealka-lization effect of 2%calcium phosphate solution is the best,with a stable pH value of 7.3.Compared with the untreated porous con-crete,the plant height of high fescue,Manila grass,and alfalfa increased by 17.9%,14.3%,and 3.9%respectively.The calcium phos-phate chemical dealkalization method has a significant influence on the pH value of the porous concrete pore solution and the plant-ing performance.Reasonably choosing the dealkalization method can optimize the performance of planting concrete.

Abstract:This paper studies the effects of different low quality recycled fine aggregate(LRFA)replacement rates(0,30%,50%,70%,100%)on the mechanical properties and durability of steam-cured concrete,and analyzes the variation rules of compressive strength,carbonation resistance,chloride ion penetration resistance,capillary water absorption characteristics and pore structure.The results show that the increase of LRFA replacement rate will significantly reduce the compressive strength and durability of steam-cured concrete,but the negative impact is relatively small when the replacement rate does not exceed 30%;When the replacement rate exceeds 50%,the concrete performance deteriorates significantly.In addition,the effects of LRFA on concrete porosity and inter-facial transition zone structure are revealed by mercury intrusion porosimetry(MIP)and micro-morphology analysis.This paper puts forward suggestions for controlling LRFA to optimize the performance of steam-cured concrete,providing technical support for the ap-plication of low-quality recycled fine aggregate.

Abstract:The optical properties of the polycarbonate material were tested,and a feasibility study was conducted on the use of polycarbonate as a substitute for lightweight window.Given its low stiffness,tests and numerical simulation analysis were also conducted to measure mid-span deflection and edge slip deformation under wind loads.Finally,air tightness,water tightness,wind pressure resistance,thermal insulation,and sound insulation performance were tested on 65 mm-thick bridge-cut aluminum polycar-bonate window.The test results indicate that the polycarbonate material meets the basic optical performance requirements for use as a glass substitute,the infrared thermal transmittance and photothermal ratio are both superior to those of ordinary glass.The de-formation at mid-span under wind load is about 3-4 times greater than that of regular glass,without posing a risk of edge slip or detachment.The overall performance of the 65-mm thermal break aluminum polycarbonate windows is excellent,with air tightness,water tightness,wind pressure resistance and thermal insulation resistance meet the standard requirements of Grade 8,Grade 6,Grade 9 and Grade 5 respectively in standard GB/T 31433-2015"General specification for building curtain walls,windowes and doors",and the sound insulation performance is also good.

Abstract:Adopting a synergistic load-bearing structure consisting of lipped thin-walled H-section steel studs,galvanized steel sheets,and ultra-high-performance concrete(UHPC)face layers,with self-tapping screws serving as shear connectors and rock wool core with edge sealing to form thermal insulation sandwich.Through flexural performance tests on three full-scale specimens,the mechanical properties of the wall panels were investigated,and formulas for calculating cracking and ultimate bearing capacity were derived based on the plane section assumption.Results indicate that the panel exhibits a clear load transfer path with firm interfa-cial bonding and no delamination.All specimens demonstrated ductile failure characterized by vertical bending cracks,with stable development of mid-span deflection and cracking.The established formulas show good agreement with experimental values and can be applied to practical engineering design.

Abstract:In this paper,the effects of two kinds of expansive agent,shrinkage reducing agent and sulphoaluminate cement on the shrinkage performance of ultra-fine cement-based grouting repair materials were studied.The results show that expansive a-gent,shrinkage reducing agent and sulphoaluminate cement can reduce the 28 d shrinkage rate of ultra-fine cement-based grouting repair materials under the condition of single admixture.Among them,the expansion agent A has the strongest shrinkage compensa-tion ability,and the sulphoaluminate cement has the weakest shrinkage compensation ability.Under the condition of compound ad-dition,compared with the compound addition of expansion agent A and sulphoaluminate cement,the addition of expansion agent A and shrinkage reducing agent can significantly reduce the 28 d shrinkage rate of superfine cement-based grouting repair material.When the content of expansive agent A and shrinkage reducing agent is 8%and 0.6%respectively,the shrinkage rate of ultra-fine cement-based grouting repair material is 0.071%at 28 d.

Abstract:Under the new circumstances of"carbon peaking"and"carbon neutrality",the evaluation and application of green building materials have become crucial means to reduce carbon emissions from products and promote the green development of the industry.Based on the analysis of the characteristics of green building materials and the fundamental principles of system construc-tion,an assessment indicator system has been developed.This system comprised three first-level indicators:environmental indicators,resource indicators,and grid compatibility.These were further refined into 12 second-level indicators that reflected the specific at-tributes of building materials.The weights of each second-level indicator were determined through comprehensive surveys involving industry professionals,resulting in a well-structured,balanced,and targeted evaluation system for green building materials in the power grid sector,accompanied by a corresponding evaluation methodology.By using concrete wall panels as examples,the scientific rigor and feasibility of the system were demonstrated.

Abstract:In-situ modified EPS particles were prepared via suspension polymerization with varying silica aerogel content.Ad-ditionally,a silica aerogel slurry was prepared using polyvinyl alcohol(PVA)dispersion,which was then mechanically mixed with in-situ EPS particles to create physically modified EPS particles.Insulating non-combustible board with low thermal conductivity was prepared by combining the aforementioned gel-in-situ/physical composite modified EPS and cement.When the content of SiO2 aerogel is 1.0%,the thermal conductivity of the in-situ modified EPS hot-pressed insulation board with aerogel is the lowest of 0.029 W/(m·K),marking a 23.7%decrease compared to unmodified EPS boards,and heat value of combustion decreases by 5.9%.When the content of 1.0%aerogel-modified EPS is 7.25%,the thermal conductivity of the insulation board prepared is 0.056 W/(m·K),and the combustion heat value is 3.0 MJ/kg.When the content of 5%PVA-modified SiO2 aerogel slurry is 12.5%and the content of 1.0%in-situ modified EPS with aerogel is 7.0%,the thermal conductivity of the aerogel composite modified EPS insulation board prepared is 0.040 W/(m·K),meeting the requirement of A2 grade non-combustible boards.

Abstract:The interface roughness is controlled by the chisel method,while the interface roughness is quantitatively controlled by setting the shear key to changing the interface characteristics.The study investigated the influence of interfacial roughness on the interfacial splitting tensile strength,straight shear interfacial strength,and oblique shear interfacial strength between sulfur-fixed ash-based fiber-reinforced cement-based composites(ECC)and existing concrete.The results show that when the roughness is 3～4 mm,ECC has the highest bond strength,and its splitting tensile strength and straight shear strength are significantly better than those of conventional concrete,and reach or even exceed the bond performance of integral pouring and interface agent.In addition,when using shear bond treatment,the oblique shear strength of ECC-C30 composite specimen is comparable to that of the integral poured specimen,showing the effect of the interface treatment to replace the interface agent.

Abstract:In this paper,epoxy/MUF microcapsules with epoxy resin as the core material and melamine modified urea-formaldehyde resin(MUF)as the shell material were prepared by in-situ polymerization.The synthesis process was optimized,and its morphology,structure,chemical composition and thermal stability,as well as the curing properties of the microcapsule-type epoxy resin adhesive mixed with self-made solvent matrix adhesive were analyzed.The results indicated that under the condition of pH 2.8～2.9,the prepared microcapsule particles were plump,with regular morphology,and showed no significant agglomeration or pre-cipitation.They exhibited good thermal stability,with an initial thermal decomposition temperature of approximately 220℃.Even under mechanical stirring at up to 2000 r/min,the structural integrity remained above 85%.When the microcapsule content was 20%,the bolt breaking torque reached a maximum value of 17.06 N·m.

Abstract:The workability of solid epoxy(PEA)-modified asphalt mixture(PESMA-13)was evaluated through dry-mixing dis-persibility,retention time,and strength development tests.Meanwhile,the pavement performance of PESMA-13 with that of SBS-modi-fied asphalt mixture(SMA-13)and anti-rutting agent asphalt mixture was compared and analyzed.The results indicate that PEA ex-hibits excellent dry-mixing dispersibility,along with the characteristics of long retention time and short curing period-its retention time reaches 6 hours,and the final strength can be achieved after curing at 60℃for 1 day.PESMA-13 demonstrates outstanding high-tem-perature rutting resistance and rapid traffic-opening capacity,with the dynamic stability(DS)of uncured specimens at 60℃and cured specimens at 60、70℃both exceeding 10000times/mm.Additionally,the low-temperature bending performance of PESMA-13 is slightly lower than that of SMA-13 but higher than that of the anti-rutting agent-modified asphalt mixture,while its water damage resistance is relatively superior.In conclusion,PESMA-13 possesses excellent workability and favorable comprehensive pavement performance.

Abstract:The process parameters have a great influence on the properties of solid waste sintered bricks.The sintering tem-perature dominates the mineral phase transformation and micro-densification.The strength and bulk density of the bricks can be optimized by heating in the suitable temperature range.The holding time regulates the liquid phase distribution and crystal phase stability,and determines the pore structure evolution and macroscopic mechanical properties.The forming pressure and moisture syn-ergistically regulate the compactness and defect formation of the green body,and it is necessary to balance the enhancement of plasticity and avoid damage.Life cycle assessment confirms that solid waste sintered bricks have significant carbon emission reduc-tion potential,and their environmental advantages are mainly due to raw material substitution and process optimization.By synergis-tically regulating the above parameters,the mechanical properties and environmental benefits of solid waste sintered bricks can be improved simultaneously.

Abstract:With the improvement of waterproofing project quality requirements,the traditional detection methods are not effi-cient enough.This paper studies the application of high-definition infrared technology in waterproof layer detection,through infrared thermal imaging to analyze the waterproofing membrane in the new roofing and underground projects of the broken,lap edges are not sticking,the corners of the hollow drums,as well as waterproofing coatings leakage,thin coating and other defects.The results show that the technology can quickly and non-contactly identify hidden problems,improve detection efficiency and accuracy,to pro-vide a scientific basis for acceptance,with simple operation,intuitive results,wide applicability and other advantages,holding signifi-cant importance in improving the quality control level of waterproofing project.

Abstract:Refer to the main erosion components of soluble salt of saline soil in Golmud area of Northwest China,sulfate and chloride single salt solutions and composite salt solutions are set up to carry out long-term immersion erosion test of fiber reinforced concrete.The effects of different erosion ions and different fibers on the deterioration process of concrete were studied.The deterio-ration model of fiber reinforced concrete is established based on Wiener process to predict the service life of concrete.The results show that 1.5%steel fiber and 0.3%basalt fiber can improve the corrosion resistance of concrete,and the steel basalt mixed fiber concrete can play a positive synergistic effect and have better corrosion resistance;Sulfate attack has great damage to the internal structure of concrete,while the erosion of concrete mass is more serious under chloride attack;The reliability model established by linear drift one-dimensional Wiener process has high fitting degree and can better predict the residual life of concrete.

Abstract:Based on the Dianzhong Water Diversion Project,the effect of adding PVA fibers on the crack resistance of hydraulic concrete was studied.The results showed that the addition of 0.9 kg/m3 PVA fiber reduced the crack of concrete flat specimens by 41.2%,increased the tension compression ratio of concrete by 0.25 percent points,increased the ultimate tensile value of concrete at 28 days by 25%,reduced the drying shrinkage of concrete at 180 days by 32×10-6,increased the comprehensive crack resistance coefficient of concrete by 11.2%,and increased the crack resistance coefficient of concrete by 25%.The crack resistance of concrete was significantly improved.The results indicate that by comprehensively considering the early crack resistance,strength,dry shrinkage,and thermal deformation of concrete,the effect of adding PVA fibers on the crack resistance of concrete can be effectively evaluated.This can provide technical support for the study of crack resistance of hydraulic concrete in the Dianzhong Water Diversion Project and theoretical reference for similar projects.

Abstract:A novel efforescence inhibitor(CuCl2·2H2O)was reported in this paper.Its strengthening mechanism on cement mortar was investigated by means of X-ray diffraction(XRD),scanning electron microscopy(SEM)and energy dispersive X-ray spectroscopy(EDS).The results show that the calcium hydroxide[Ca(OH)2]produced in the initial stage of cement hydration is consumed by Cupric chloride dihydrate(CuCl2·2H2O),which can suppress the phenomenon of efflorescence in cement mortar,promote the later hydration of tricalcium silicate(C3S)and dicalcium silicate(C2S)in cement,thus enhancing the compressive strength of cement mortar.

Abstract:For the cracking and bleeding problems on the bridge deck grouting of expressways,a water-resistant and highly flexible polyurethane grouting material was developed.Through indoor experiments,the main influencing factors on performance were optimized.When the mass ratio of sodium silicate to the composite polyol is 80∶20,the content of the toughening agent is 10%,the mass ratio of MDI to pre-PU is 60∶40,and the diluent content is 20%,the water-resistant and highly flexible polyurethane has the best performance,with a tensile strength of 3.9 MPa,an elongation of 139%,a compressive strength of 7.4 MPa,and a flexural tensile strength of 5.4 MPa.Comparison results show that the two-component hydrophobic polyurethane is sensitive to water,expands when exposed to water,and its performance deteriorates.The two-component micro-expanding and water-resistant highly flexible polyurethane are not sensitive to water and have good durability in humid environments.However,the two-component micro-expanding polyurethane has almost no flexibility.

Abstract:Four UHPC connection beams,two grouted sleeve connection beams and two monolithic cast-in-place beam specimens were designed based on different strength grades of reinforcement.Four point bending tests were carried out on the specimens,and the failure modes,load-displacement curves and load-strain curves of the specimens were compared and analyzed.The test results show that the strength grade of reinforcement can significantly improve the flexural capacity of UHPC connecting beams.When the strength grade of reinforcement is increased from HRB400 to HRB500,the yield load and ultimate load of UHPC connecting beams increase by about 19%～22%;When the anchorage length of HRB400 reinforcement is not less than 8d,and the anchorage length of HRB500 reinforcement is not less than 10 d,the bearing capacity of the specimen is basically the same as that of the cast-in-place beam,which can achieve the effect of"equivalent cast-in-place";UHPC cooperates with reinforcement to bear tensile stress,significantly enhances the stiffness of the specimen connection area,and effectively inhibits the generation and development of cracks in the connection area.

Abstract:The workability,rheological properties,mechanical properties,and durability of C50 segmental concrete were inves-tigated under the condition of compounding two types of composite amino alcohol rust inhibitors(R1,R2)with two types of poly-carboxylic acid-based water reducers(W1,W2),and a correlation analysis was conducted.The results show that the effects of cor-rosion inhibitors R1 and R2 on the slump,expansion and setting time of concrete are different,which is mainly related to the dif-ferent components of alcohol amine corrosion inhibitors.The two kinds of corrosion inhibitors will increase the yield stress and plastic viscosity of concrete,but their action mechanisms are different.The emptying time can characterize the rheological properties of concrete to a certain extent.Compared with concrete only mixed with superplasticizer,the 1 d-compressive strength of concrete can be increased by 7.8%～10.3%,and there is no adverse effect on the 56 d-compressive strength.The dynamic elastic modulus of 1 d can be increased by 6.7%～10.2%,and the 56 d-electric flux of concrete can be reduced by 6.3%～23.8%.Among them,the effect of corrosion inhibitor R2 is better.

Abstract:In order to prepare rapid hardening UHPC for emergency repair and reinforcement in cold winter regions,the effects of retarder and steel fiber content on the working and mechanical properties of UHPC were discussed.The results show that the higher the dosage of retarder,the longer the setting time of UHPC and the lower the loss of expansion.When the dosage of retarder is 0.75%,the comprehensive performance of UHPC is the best,the 4 h and 24 h compressive strength are 50 MPa and 82 MPa,re-spectively;while 4 h and 24 h bonding strength are 2.8 MPa and 4.7 MPa,respectively.With the increase of steel fiber content,the bonding strength and flexural toughness of UHPC increase.The 28 d bond strength and flexural strength of UHPC with 1.5%steel fiber content were 9.5 MPa and 22.6 MPa,respectively,and the strength improvement was not significant with the increase of steel fiber content.The durability of UHPC is much better than that of C50 steel fiber reinforced concrete by frost resistance and chloride ion migration coefficient test,which is suitable for emergency repair and reinforcement in cold winter regions.Combined with the concrete replacement engineering application of Heha high-speed expansion joint anchoring area in Heilongjiang Province,the rapid hardening UHPC can be opened to traffic 4 h after pouring,and there is no damage phenomenon after two years of operation through freeze-thaw and deicing salt environment.