Experiment And Analysis On Flexural Toughness And Shear Strength Of Shrinkage-compensating Steel Fiber Reinforced Shotcrete

Shrinkage-compensating steel fiber reinforced shotcrete is advanced composite material. Using the vitues of both steel fiber reinforced concrete and shrinkage compersated concrete, and adding steel fiber and expansive agent into the shotcrete, shrinkage-compensating steel fiber reinforced shotcrete can not only improve the quality of shotcrete, but also increase strength and toughness. The maximal effect of steel fiber for shrinkage-compensating steel fiber reinforced shotcrete on the reforcemance of toughness which is different form traditional steel fiber reinforced concrete.The fraction of steel fiber by volume and the addition percentage of expensive agent as variable to carry out orthogonal test is presented in this paper, design16groups mix proportion,256specimens. Experimental investigation of flexural toughness and ultrasonic defect detection and shear strength of16shotcrete beams and48steel fiber shotcrete and48shrinkage-compensating concrete and144shrinkage-compensating steel fiber reinforced shotcrete are studied. The main research work is performed as follows:Using three-point bending mothod, the flexural toughness of these Four-concrete are carried out, and the load-deflections are abtained through date acquision. The evaluation of the parameters of flexural toughness is made according to testing date, by means of ASTM C1018toughness index and flexural toughness coefficient method of JCI and test mothod of Chinese, which is implemented by2010. based on test date, the influence analysis of the composite effect of steel fiber and expansive agent on flexural toughness improved with the fraction of steel fiber by volume increased. The parameter strength is the most highest, the load-deflection is the most full, and the ductility is the most remarkable for shrinkage-compensating steel fiber reinforced shotcrete, which have steel fiber constrancts under the8%expensive agent.The defects of the internal structure of the concrete is tested by ultrasonic. A pair of measuring points is choosed, which ranging is400mm. The analysis shows that the evaluation of celocity of concrete which adding steel fiber in it can not be in the same breath with that of no fiber, because of the differerce of the geometry size and distribution of steel fiber. The velocity of the shrinkage-compensating concrete reach the maximum under the6%expansive agent; the concrete which is added steel fiber is dense, and with the increase of fraction of steel fiber by volume, the compaction will be inproved, however, the enhancement of velocity adding exceddive fiber is not significant and the excessive fiber has duster property; the velocity of concrete with the the same volume fraction of fiber reach the maximum under the8%expansive agent and the quality is the best.According to the requrements of the test mothod for shear strength of fiber reinforce concrete in<Technical specification for application of fiber reinforced concrete>(JGJT221-2010), the experiment of these Four-concrete are carried out. The research shows that the influence of steel fiber on shotcrete is remarkable very much no matter what expansive agent is added or not, and how much it will be, moreover, the more fraction of steel fiber by volume, the higher the shear strength. The influece of right amount of expansive agent on shotcrete is greater, however, the decreasing range of shear strength is high when excessive fiber is mixed. Syuergistic and compounding effect among steel fiber and expansive agent are signigicant.According to the test date and comprehensive analysis, the shrinkage-compensating steel fiber reinforced shotcrete will be widely applied in practical engineering. And the best match dosages of wxpansive agent and steel fiber are8%and1.2%for shrinkage-cmpensating steel fiber reinforced shotcrete.