Abstract:The durability experiments of shotcrete with and without steel fiber under bending stress in accelerated carbonation corrosive environments were carried out to investigate the carbonation regularity of tunnel lining. Meanwhile

the concrete carbonization predictive model was modified for considered bending stress

steel fiber addition and construction mode. The results showed that the carbonation depth was obeyed Fick first law and diffusion coefficient was raised with the bending stress level increased. The carbonation depth of shotcrete was much less than that of ordinary concrete. Simultaneously

the carbonation resistance of steel fiber reinforced shotcrete (SFRS) was much better than that of shotcrete. For analyzing the mechanical properties and microstructure of shotcrete after carbonation

the cubic compressive strength

splitting tensile strength and flexural strength were increased with carbonation depth raised. The channels for carbon dioxide taking into shotcrete were provided by the original micro pores and creaks. Moreover

the favorable conditions for calcite crystal nucleation and growing were also supplied by ettringite and portlandite which consists in defeats. With the carbonation reaction development

the carbonation products were continuously consumed and blocked the micro-pores.