Monitoring And Investigation Of Steel Bar Corrosion Stress In Concrete By DIC

Reinforced concrete structure is still one of the most important building materials in today's society,which is widely used in various engineering projects.However,the damage of reinforced concrete during use is becoming more and more serious,especially in harsh environmental conditions such as the ocean.The damage caused by the corrosion of steel bars in concrete can not be underestimated.The corrosion products generated by the corrosion of the steel bar after blunting cause the concrete protective layer to rust and crack,eventually leading to the destruction of the reinforced concrete structure.In extreme cases,the damage may be catastrophic,causing huge losses to people's life safety and economy.Therefore,the whole process of rust expansion and cracking of concrete protective layer caused by steel corrosion is effectively monitored in real-time strain field,which is of key significance for the analysis of service performance and life cycle of reinforced concrete structures.In this paper,the internal and external monitoring method is adopted to solve the corrosion problem of steel bar in concrete.Under the condition of constant potential accelerated corrosion,the corrosion behavior of reinforced concrete,the development process of rust expansion force and the evolution law of concrete surface strain field were systematically analyzed.Taking this as the main line,the main research results obtained in this paper are as follows:?1?Digital image correlation technology?DIC?based on natural speckle image matching and tracking,the whole process of rust expansion and cracking of concrete protective layer caused by steel corrosion was monitored in the electric accelerated external infiltration device.The internal and external strain evolution of corroded reinforced concrete specimens was analyzed.The form and trend of crack of reinforced concrete were expounded.The full-field stress monitoring system of corroded reinforced concrete based on DIC technology was established.?2?According to the data of the strain gauge on the inner surface of hollow steel bar used in this paper,it was concluded that the corrosion of reinforced concrete is non-uniform.Then,the mathematical model of rust expansion force for corroded steel was derived.And the crack form and trend of reinforced concrete specimen were expounded.Finally,according to the evolution of corrosion current density,the crack time of reinforced concrete specimen was determined.?3?The full-field stress monitoring system based on DIC technology was used to compare and analyze the impact of steel bar corrosion in concrete under different factors.Based on the test,it can be concluded:Firstly,the common reinforcement was more prone to corrosion reaction when affected by corrosion ions,and the corrosion-resistant reinforcement had a certain inhibitory effect on the process of corrosion reaction.Secondly,the effect of corrosion solution on the corrosion rate of steel bar was sea solution>3%Nacl solution>3%Nacl+5%Na₂SO₄ solution.The last one is that the incorporation of mineral powder,fly ash and SAP effectively inhibited the corrosion process of steel reinforcement in concrete.?3?X-ray computed tomography?XCT?is a good nondestructive testing method.A new method combining digital image related technology?DIC?and X-ray computer tomography?XCT?is proposed for the first time The effect of steel corrosion on the interior of concrete was monitored in real time by using the new method.Moreover,the feasibility of monitoring the deformation and fracture of concrete in any area during the whole corrosion process is verified.The expansion and evolution law of concrete internal crack caused by rust expansion stress caused by steel corrosion was also analyzed.