Experimental Research On Carbonization Properties Of TRC Sheets And Flexural Behavior Of Corroded Reinforced TRC Composite Beams

The vigorous development of China's construction industrialization is bound to bring revolutionary progress in the history of building engineering.In this paper,the permanent formwork using textile reinforced concrete was studied.The formwork firstly uses stainless steel grid to fix fabric net,and then is prefabricated with high performance fine aggregate concrete.On the one hand,permanent formwork can protect cast-in-place concrete inside and enhance its durability.On the other hand,permanent formwork acts as part of the structure to participate in structural stress.Thus,the mechanical properties of the structure are improved.The application of prefabricated textile reinforced concrete(TRC)permanent formwork needs to deal with the durability challenge.The specific contents of this paper include the following two aspects:The first is the experimental study on the mechanical properties of TRC sheets under the coupling of force and carbonation,the second is the experimental study on the anti-bending capability of TRC composite beams under the coupling of force and chloride erosion.The main research contents are as follows:(1)The accelerated carbonation test was carried out for some TRC sheets and plain concrete sheets,then destructive loading test was carried out under the normal climate conditions.In the process of the experiment,the change of its failure modes and the degradation of the ultimate bearing capacity were observed and compared with those of plain concrete sheets,the analysis of its failure mechanism was put into the end.The results of research show that TRC sheets have great advantages in flexural properties and shear properties over plain concrete sheets.The bearing capacity and deformation ability of TRC sheets are greatly improved,the failure process of TRC sheets reflects the characteristics of ductile failure: cracks appear in the concrete first,then the fabric net is broken and cut off.However,the appearance of cracks in cast-in-place concrete sheets indicates the end of loading,which reflects the characteristics of brittle failure.With the increase of carbonization time,the bearing capacity of TRC and ordinary concrete sheet are improved in different degrees(2)Formulas for calculating cracking load and ultimate flexural capacity were obtained by carrying out the theoretical deduction of the cracking load and ultimate flexural capacity of TRC sheets,ideal calculation results were obtained by verifying the formulas with the data of this experiment.The carbonation depth of plain concrete sheets was calculated according to the existing carbonation depth prediction model and compared with that of TRC sheets,and then the reason for the differences were analyzed.Research shows:The carbonation depth of TRC sheet is less than that of ordinary concrete slab.(3)Fabrication of composite beam members using prefabricated textile reinforced concrete(TRC)permanent formwork,and adopt the method of electrochemical corrosion,analysis of the 2 contrast beams and 5 TRC composite beams under the different actions of solution concentration,sustained load state,corrosion rate of TRC superposed flexural performance of the beams in chloride erosion condition.Results show: The degradation of mechanical properties of TRC composite beams under corrosion condition is better than ordinary beams;The "U" shape of the TRC beam model can hinder the infiltration of chloride ions,delaying the corrosion of steel;The yield load and ultimate load of the TRC composite beam are slightly increased at a low corrosion rate.With the increase of solution concentration,the corrosion rate of steel bar increases gradually,and the bearing capacity of TRC composite beam shows a downward trend.(4)The theoretical analysis of the flexural capacity of the TRC composite beams under corrosion condition was made.Based on the theory of structural mechanics,material mechanics and mathematics,the formula for calculating the flexural capacity of TRC composite beam under the coupling of force and chloride corrosion was derived.Compared with the actual experiment results,the calculating value is in good agreement with experimental data.