Multi-factor Model Of Concrete Carbonation Depth And Durability Analysis Groundwater

Concrete carbonization is one of the important factors that cause steel depassivation and corrosion.Similar to the atmospheric environment,concrete structure in groundwater of aggressive C02 will also suffer carbonation and steel will be corroded,eventually concrete structure is damaged.In this paper,a tests device of accelerated carbonation in groundwater of aggressive C02 is developed and a corresponding analytical method is proposed.Concrete carbonation test considering the influence of coarse aggregate and the%accelerated carbonation tests in groundwater are developed respectively.Based on the test results the carbonation depth multi-factor model considering the influence of coarse aggregate in groundwater environment is established.Finally,the durability analysis methods of concrete structure are presented for groundwater environment.The main research work includes:1.Using plexiglass tubes to simulate coarse aggregate and putting them distribute in the mortar regularly could reflect the influence of coarse aggregate volume fraction,size,shape and mechanism sand replacement,water-binder ratio on the carbonation depth.A prediction model for the carbonation depth considering the impact of coarse aggregate is established based on the test results.By comparing the model value with the test value,the accuracy and applicability of model is verified.2.The preparation method of underground artificial aggressive C02 solution with corrosive CO₂ and the test method of accelerating carbonation of concrete in corrosive CO₂ groundwater environment are proposed,and a corresponding test apparatus is developed.The apparatus and methods can steady the variation coefficient of aggressive C02 concentration in soaking solution in the range of 0.15 during the experiment,forming a stable groundwater environment of aggressive C02.Thus,the concrete accelerated carbonation test in groundwater of aggressive C02 can be performed at normal atmospheric pressure.3.The accelerated carbonation tests in the groundwater are performed by using the above two kinds of devices.Experiment researched the influences of carbonation age,water-binder ratio,fly ash replacement,slag replacement and the concentration of aggressive C02 on the concrete carbonation depth.According to the tests results,the carbonation depth multi-factor model considering the influence of coarse aggregate and time-varying model in groundwater are proposed based on the least-square method.By comparing the model value with the test value,the availability of model is verified.4?Based on the carbonation depth multi-factor model considering the influence of coarse aggregate in groundwater,the structural element with different mixing ratio affected by one-dimensional carbonation and two-dimensional carbonation are analyzed in durability respectively.The results show that the design of concrete structures in groundwater of aggressive C02 on the basis of GB 50046-2008 Code for Anticorrosion Design of Industrial Constructions can meet the requirements of the service life of 100 years.