[Objective]In the severe cold region of China,freeze-thaw damage can cause recycled concrete(RAC)structures to reach the durability limit earlier or even lead to component failure,to prolong the service life of recycled concrete(RAC)struc-tures in severe cold region,[Methods]freeze-thaw cycling tests were conducted on recycled concrete(RAC),natural concrete(NC),plain steel fiber recycled concrete(PFRAC)and stainless steel fiber recycled concrete(SFRAC)were subjected to freeze-thaw cycle tests.After freeze-thaw cycles,the mass loss and relative dynamic elastic modulus of RAC,NC,PFRAC,and SFRAC were measured to analyze the internal damage mechanism and deterioration law of concrete during freeze-thaw cycles.The relative dynamic elastic modulus was used as the damage variable,and a freeze-thaw damage model for steel fiber recycled con-crete was established based on the Response Surface Model(RSM)and the Weibull distribution to study the effects of the num-ber of freeze-thaw cycles and the admixture of PF and SF on the frost resistance of recycled concrete.[Results]The result show that SF incorporation can effectively delay the loss of mass and the decrease of the relative dynamic elastic modulus of RAC.At 150 freeze-thaw cycles,the mass loss and relative dynamic elastic modulus of SFRAC with 2％dosage decreased by 3.01％and 19.57％,respectively.The mass loss rate of SFRAC was reduced by 0.4％and the relative dynamic elastic modulus increased by 14.17％compared with that of RAC.[Conclusion]The prediction result of Weibull distribution and Response Surface Modeling(RSM)are basically the same,but the relative error of the predicted value of RSM is lower than that of Weibull distribution.The correlation coefficients R2 of the two models are above 0.94,and the prediction result are more accurate,which can provide theo-retical references for the use of steel fiber recycled concrete in cold regions.
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