Research On The Properties And Synergistic Reinforcement Mechanism Of Fiber-loaded Microbial Self-healing Concrete

Concrete as the most widely used building materials in civil engineering,but inevitably there are certain material performance defects in concrete prone to cracking during the forming and service period,if these cracks are not dealt with in a timely manner and allowed to develop,it will accelerate the intrusion of harmful ions into the concrete interior,leading to corrosion of reinforcement and premature deterioration of the structure.Based on this,a fiber-supported microbial material was prepared in this paper to actively repair concrete cracks by inducing calcium carbonate crystal precipitation,which changed the passive treatment of concrete cracks into active crack repair and improved the service life of concrete materials.The pores of fibers are mainly used as the carrier of microorganisms to mix ready-mixed concrete.When cracks occur in concrete,erosive substances infiltrate and activate dormant microorganisms,and calcium carbonate is generated through microbial mineralization deposition to realize self-repair of cracks.Meanwhile,the enhancement of concrete performance by fibers is utilized to realize its synergic enhancement.Through experimental testing,theoretical analysis and numerical simulation,the main research conclusions are as follows:（1）Optimization of microbial culture and repair effect.By cultivating microbial bacteria,optimize the microbial load process,determine the ratio of mixed mode and,further simplifies the cultivation of microorganism domesticated and load,optimized fiber fixed load steps of microbes,push microbial self-healing concrete in practical engineering applications,28 d average width for the experiment of crack repair repair is 0.87 mm,The maximum crack repair width is 1.32 mm.（2）Mechanical and durability performance study of fiber-loaded microbial self-healing concrete.In the splitting tensile strength test,the damage of fiber-loaded microbial concrete tends to be more plastic,which is 28.7% higher than that of ordinary concrete;in the test of resistance to water pressure infiltration,the permeation height of fiber-loaded microbial concrete increases at the same water pressure compared with that of ordinary concrete;in the resistance to chloride ion migration coefficient,its resistance to chloride ion migration coefficient decreases compared with that of ordinary concrete,and its resistance to chloride ion In the microscopic analysis,the SEM microscopic morphology of the microbial self-healing concrete at the age of 28 d showed that the hydration reaction was sufficient and the interfacial structure was more integral.（3）A fiber-loaded microbial fracture repair model was constructed.Based on the crack repair model and aggregate random model of microbial self-healing concrete,concrete materials with different mix ratios were simulated for crack diffusion,and repair models were constructed to verify the progressive failure to repair of concrete.The comparison results of crack repair rates in combination with the tests showed that: The average repair rate of the specimen is 83%,and the repair rate of the numerical simulation is 76%.The repair rate of the simulated value is lower than that of the experimental value,and the error value is 9.2%.（4）Analysis of the synergistic reinforcement mechanism.Based on the composite material theory to analyze the influence law of compressive stress-strain of concrete with different ratios from the mechanical point of view,the results show that the addition of microorganisms slightly improves the elastic modulus of concrete,and the addition of fibers enhances the concrete performance more;analyzed from the microscopic point of view by SEM images combined with experiments,the microorganism-loaded fibers and the fiber-loaded microbial material itself on the crack generation,development and self-healing The fibers have microscopic reinforcing effect on concrete materials,mainly the enhancement of concrete by the loaded microbial fibers compensates for the internal defects of concrete,and the fiber-microorganism synergistically promotes the enhancement of self-healing concrete materials.