Study On Self-healing Performance Of Fiber Reinforced Tailing Sand Cementitious Composites

Self-healing is the phenomenon that cracks were filled with second hydration products of unhydrated or insufficiently hydrated binder particles in damage regions.The application of self-healing theory on cementitious composites,has many advantages over hunman-induced restoration.However,the researches is still on the exploration stage.Green Toughness Cementitious Composites(GTCC)was the research material in the research.Self-healing theory was combined with self-healing tests,the self-healing performance of GTCC was investigated in this research.Factors such as damage age,self-healing age,curing condition was condidered in this research.The self-healing performance of self-healing and self-healing evolution law was analyzed,which was evaluated by strength recovery evolution method and damage self-healing evoluated method based upon damage theory,these methods was based upon strength indicators,supersonic wave velocity and resonnat frequency testing technology.The main research aspects and conclusions are as follows:Study based on strength recovery method was investigated.Compressive test was applied in this research,test specimens was experienced precracked and self-healing curing,strength was used to characterized the self-healing degree.Damage age,self-healing age,curing condition and wet-dry curing cycles was disscussed in the influence of the self-healing performance of GTCC.The self-healing performance was remarkable under damage age,self-healing performance improved with the earlier damage age.The performance improved with the prolongation of self-healing age,but the latter growth was not obvious relatively.The performance under water curing and wet-dry curing were apparent higher than air curing,the effect promoted was mainly occured before 21 cycles under wet-dry curing.Study based on supersonic wave and resonant frequency testing technology was carried out.Damage condition and self-healing effect of damaged test specimens was characterized by damage factor and damage recovery ratio,damage characterized premeters was extracted through supersonic wave and resonant frequency testing.The self-healing performance was described quantitatively.Under supersonic wave testing,self-healing performance was better with the earlier damage age,the improvement effect was obvious when damaged at 7d,Self-healing performance was improved with the self-healing age increased,the effect was nearly recoverd entirely.Self-healing performance was best under water curing,wet-dry curing was slightly lower than former,and was not obvious under air curing.Under resonnat frequency testing,self-healing performance declined with the increase of damage age,it’s nearly to recovered at 7d damaged.Self-healing performance was improved with the increase of self-healing age,the damage recovery ratio was primarily before 60 d.The improve of self-healing was obvious under water curing and wet-dry curing,and not obvious under air curing.The growth of self-healing performance was occured before 14 cycles and 28 cycles.These two testing technologies could make the same appraisal for self-healing of GTCC,they could complement each other used in the test.Damage evolution model was established,which was combined with damage theory and supersonic testing technology.This model could make a more resonable evalution for self-healing.The process of damage self-healing was divided into three stages,self-healing was primarily occured in the medium term and late stage.The process of damage evolution process was closely related to the second hydrated reaction of damaged specimens.The evolution make a reasonable and accurate description for the changing relation between damage recovery ratio and self-healing age.