Research On The Observation Method Of The Corrosion Of The Internal Reinforcement Of Concrete In The Saline Alkali Environment

Concrete structure is widely used,and various factors lead to the failure of the structure.Among them,the physical and chemical erosion of the external environment?such as the saline alkali environment?is one of the main factors leading to the damage of the concrete structure.Xinjiang is located in the cold area of Western China,which is the main area of salt and alkali development.Through the analysis of the soil and water samples collected in the typical saline alkali area of Xinjiang,the species and content of erosion ions were determined.In order to simulate the concrete components eroded by salt and alkali environment,different concentrations of Na₂SO₄ and NaCl solution are prepared to mix concrete raw materials and make reinforced concrete test blocks.Observe the resistivity and polarizability of the test block,and study the corrosion state of the internal reinforcement of concrete and the response law of electrical parameters.The results show that: with the increase of age,the conductivity of the test block decreases and the polarization effect increases;under the same concentration,the conductivity of the sulfate test block is lower than that of the chloride test block,while the polarization effect is stronger than that of the chloride test block;there are certain differences in the electrical parameters of the test block with different concentration of the same ion;at the early stage of corrosion of the steel bar,the values of resistivity and polarization rate increase;The resistivity of concrete test block is greatly affected by the reinforcement,while the polarization is less affected by the distribution of reinforcement,which shows that it is feasible to use the polarization parameter to study the corrosion of concrete structure by salt and alkali.The structural safety inspection is carried out for the bridge pier of the in-service coastal railway line.The survey line shall be reasonably arranged in combination with the landform and the geographical environment around the pile.Using the Wenner device,the existence area of high apparent resistivity and high apparent polarizability is preliminarily determined.Then,the survey line is set on the side of the pile body,and the abnormal amplitude changes of apparent resistivity and apparent polarizability are compared and analyzed to eliminate the interference of the soil around the pile body and the local abnormal body below the soil layer,so as to determine that the abnormal body is located inside the pile body.Then,the depth of the abnormal body was measured by five pole longitudinal sounding device.At the same time,combined with the proposed penetration device,determine the specific location of possible reinforcement corrosion,and determine the size of the hidden danger body.Based on the above-mentioned apparent resistivity and apparent polarizability observation devices,the interference factors of the surrounding medium of the pile body can be eliminated gradually,and the position of the hidden danger body inside the pile body can be determined.The method is effective and feasible.