Study on reinforcing and toughening effect of steel fiber on cementitious materials under dry thermal environment
In order to study the reinforcing and toughening effect of steel fiber on cementitious materials under dry thermal environment,it takes the dry thermal environment of high ground temperature tunnel as the background,divides the temperature of tunnel surrounding rock into four levels(40℃,60℃,80℃ and 100℃)and sets up the corresponding simulated environment through research,and studies the effects of different dry thermal environments on the strength of cement mortar,interfacial bonding between steel fiber and cement mortar and steel fiber through mechanical property tests.The effects of different dry thermal environments on cement mortar strength,steel fiber-cement mortar interfacial bonding and steel fiber pull-out work were investigated through mechanical property tests,the deterioration mechanism of dry thermal environment was analyzed,and finally the fracture performance of steel fiber concrete was verified by comparison.The following conclusions were mainly obtained:(1)The dry hot environment is favorable to the growth of the compressive strength of cement mortar and the interfacial bond strength of steel fiber and cement mortar in the early stage.After 7 days the compressive strength of cement mortar and the interfacial bond strength of steel fiber and cement mortar in the dry hot environment are significantly lower than those in the standard curing environment,and the degree of decline is positively correlated with the temperature.(2)The pull-out work of steel fiber-cement mortar under dry heat environment is greater than that under standard curing conditions,indicating that the dry heat environment can improve the toughening effect of steel fiber,but the toughening effect of steel fiber decreases when the temperature is too high.(3)With the increase of temperature,the fracture energy of steel fiber-concrete specimens showed a trend of increasing and then decreasing,and the maximum value of fracture energy appeared at 60℃.
temperature of surrounding rockdry thermal environmentbond strengthfiber pull-out workfracture energy
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