In order to investigate water and chloride ion transport in damaged concrete, three types of concrete were prepared, freeze-thawing（F-T） cycling and compressive loading were adopted to induce damage to concrete. Ult...In order to investigate water and chloride ion transport in damaged concrete, three types of concrete were prepared, freeze-thawing（F-T） cycling and compressive loading were adopted to induce damage to concrete. Ultrasonic pulse velocity technique was used for evaluating the damage degree of concrete, and the defects of damaged concrete were also detected by X-CT. Water absorption and chloride ion penetrability were used for describing the transport properties of damaged concrete. Effects of damage degree on the water absorption rate and chloride ion penetrability were investigated in detail and the relationships were also established. The results show that the water absorption of concrete makes various responses to damage degree due to the difference of concrete type and damage method. For same concrete with similar damage degree, the water absorption rate of F-T damaged concrete is usually larger than that of concrete damaged by loading. The chloride ion penetrability of damaged concrete increases linearly with increasing damage degree, which is more sensitive to damage degree if the original penetrability of sound concrete is higher.展开更多
In marine environments,reinforced concrete bridge structures are sub-jected to cyclic loads and chloride ingress,which results in corrosion of the rein-forcing bars,early deterioration,durability loss,and a considerab...In marine environments,reinforced concrete bridge structures are sub-jected to cyclic loads and chloride ingress,which results in corrosion of the rein-forcing bars,early deterioration,durability loss,and a considerable reduction in the fatigue strength.Owing to the complexity of the problem and the difficulty of testing,there are few studies on the fatigue performance of concrete structures under the combined action of corrosion environment and cyclic load.Therefore,a coupling test device for corrosion and cyclic load is designed and fatigue tests of reinforced concrete beams in air environments and chlorine salt corrosive envir-onments are carried out.The fatigue corrosion process,damage mode,and corro-sion features of the test beams as well as chloride ion content in concrete are analyzed.The relationships of deflection,crack,and number of cycles in the dif-ferent environments are given.Results show that the fatigue life of the beam is.greatly reduced under coupled effects of the cyclic load and corrosive environ-ment,the failure fom of the beam is corrosion fatigue damage.The deflection and crack keeps growing with the increase in loading cycles.Under the coupling of cyclic load and corrosion env ironment,the content of chloride ion in concrete is low and there is less variety along the direction of penetration.展开更多
In this paper,the durability of cement mortar prepared with a recycled-concrete fine powder(RFP)was examined;including the analysis of a variety of aspects,such as the carbonization,sulfate attack and chloride ion ero...In this paper,the durability of cement mortar prepared with a recycled-concrete fine powder(RFP)was examined;including the analysis of a variety of aspects,such as the carbonization,sulfate attack and chloride ion erosion resistance.The results indicate that the influence of RFP on these three aspects is different.The carbonization depth after 30 days and the chloride diffusion coefficient of mortar containing 10%RFP decreased by 13.3%and 28.19%.With a further increase in the RFP content,interconnected pores formed between the RFP particles,leading to an acceleration of the penetration rate of CO_(2)and Cl^(−).When the RFP content was less than 50%,the corrosion resistance coefficient of the compressive strength of the mortar was 0.84-1.05 after 90 days of sulfate attack.But the expansion and cracking of the mortar was effectively alleviated due to decrease of the gypsum production.Scanning electron microscope(SEM)analysis has confirmed that 10%RFP contributes to the formation of a dense microstructure in the cement mortar.展开更多
基金Funded by the Major State Basic Research Development Program of China(973 Program)(No.2015CB655102)the National Natural Science Foundation of China(Nos.51178106,51378116&51408597)the Scientific and Technological Research and Development plan of China Railway Corporation(No.2013G001-A-2)
文摘In order to investigate water and chloride ion transport in damaged concrete, three types of concrete were prepared, freeze-thawing（F-T） cycling and compressive loading were adopted to induce damage to concrete. Ultrasonic pulse velocity technique was used for evaluating the damage degree of concrete, and the defects of damaged concrete were also detected by X-CT. Water absorption and chloride ion penetrability were used for describing the transport properties of damaged concrete. Effects of damage degree on the water absorption rate and chloride ion penetrability were investigated in detail and the relationships were also established. The results show that the water absorption of concrete makes various responses to damage degree due to the difference of concrete type and damage method. For same concrete with similar damage degree, the water absorption rate of F-T damaged concrete is usually larger than that of concrete damaged by loading. The chloride ion penetrability of damaged concrete increases linearly with increasing damage degree, which is more sensitive to damage degree if the original penetrability of sound concrete is higher.
基金The author(s)received funding for this study from Open Research Fund Program of State key Laboratory of Hydroscience and Engineering(No.sklhse-2018-C-05).
文摘In marine environments,reinforced concrete bridge structures are sub-jected to cyclic loads and chloride ingress,which results in corrosion of the rein-forcing bars,early deterioration,durability loss,and a considerable reduction in the fatigue strength.Owing to the complexity of the problem and the difficulty of testing,there are few studies on the fatigue performance of concrete structures under the combined action of corrosion environment and cyclic load.Therefore,a coupling test device for corrosion and cyclic load is designed and fatigue tests of reinforced concrete beams in air environments and chlorine salt corrosive envir-onments are carried out.The fatigue corrosion process,damage mode,and corro-sion features of the test beams as well as chloride ion content in concrete are analyzed.The relationships of deflection,crack,and number of cycles in the dif-ferent environments are given.Results show that the fatigue life of the beam is.greatly reduced under coupled effects of the cyclic load and corrosive environ-ment,the failure fom of the beam is corrosion fatigue damage.The deflection and crack keeps growing with the increase in loading cycles.Under the coupling of cyclic load and corrosion env ironment,the content of chloride ion in concrete is low and there is less variety along the direction of penetration.
基金This work is supported by the Zhuhai Science and Technology Project(ZH22036203200015PWC)the Open Foundation of State Key Laboratory of Subtropical Building Science(2022ZB20).
文摘In this paper,the durability of cement mortar prepared with a recycled-concrete fine powder(RFP)was examined;including the analysis of a variety of aspects,such as the carbonization,sulfate attack and chloride ion erosion resistance.The results indicate that the influence of RFP on these three aspects is different.The carbonization depth after 30 days and the chloride diffusion coefficient of mortar containing 10%RFP decreased by 13.3%and 28.19%.With a further increase in the RFP content,interconnected pores formed between the RFP particles,leading to an acceleration of the penetration rate of CO_(2)and Cl^(−).When the RFP content was less than 50%,the corrosion resistance coefficient of the compressive strength of the mortar was 0.84-1.05 after 90 days of sulfate attack.But the expansion and cracking of the mortar was effectively alleviated due to decrease of the gypsum production.Scanning electron microscope(SEM)analysis has confirmed that 10%RFP contributes to the formation of a dense microstructure in the cement mortar.
