| The corrosion of steel bar caused by chloride ion erosion caused huge economic losses,which threatens the durability of concrete structure seriously.Fiber can effectively improve the durability of concrete,and it is difficult to improve the performance of concrete multi-aspect and multi-angle by using a single kind of fiber.Only a variety of fiber complementing each other can improve the overall performance of concrete.At present,researches on the resistance to chloride ion permeability of hybrid fiber reinforced concrete are very limited,so the resistance to chloride ion permeability of hybrid fiber reinforced concrete was studied,meanwhile,the methods to improve the performance of resistance to chloride ion permeability were researched,and the analysis of this performance from the aspects of macroscopic and microscopic was performed in this thesis.This study can provide the scientific basis for the further research and application.The research contents are as follows:Based on the experimental study of the influence of fiber volume content on the resistance to chloride ion permeability of concrete,16 different fiber volumes and 5 different curing periods were designed in the thesis,and the performance of hybrid fiber reinforced concrete with different fiber content in different curing age was studied by electric flux test.The results showed that low dosage of fiber against the resistance to chloride ion permeability of concrete(When the volume content of fiber is 0.1%),reasonable dosage of hybrid fiber can improve this performance of concrete and the effect is more obvious along with the age growth.Based on the hybrid fiber dosage with the best resistance to chloride ion permeability of concrete,12 different dosage of mineral admixture and 4 different dosage of chemical admixture were designed in this thesis,and the effect of improving this performance from the fly ash,silica fume,air-entraining admixture and expansion admixture were studied by electric flux test,and the influence of hybrid fiber reinforced concrete on compressive strength from these was also studied in the meanwhile.The results showed that mineral admixture,reasonable dosage of air-entraining admixture and expansion admixture can effectively improve the resistance to chloride ion penetration performance of hybrid fiber reinforced concrete.In addition,mixed mineral admixtures with reasonable dosage isadvantageous to improve the compressive strength of hybrid fiber concrete,air-entraining admixture can cause small compressive strength loss of hybrid fiber reinforced concrete,and the loss was greater with the more dosage.Expansion admixture with reasonable dosage can slightly improve the compressive strength of hybrid fiber reinforced concrete and too much can lead to the loss.Based on the macroscopic phenomena,the pore structure of hybrid fiber reinforced concrete was studied by mercury injection experiment in this thesis.The results showed that basalt-polypropylene hybrid fiber with reasonable dosage had positive meaning for optimizing the internal pore structure of concrete and the most obvious effect of optimizing along with the curing age increasing,and mineral admixtures can effectively optimize the pore structure and the improved effect is more significant when fly ash and silica fume hybrid.Chemical admixture with a reasonable dosage can effectively improve the pore structure,which makes internal structure denser. |
