The Research On Interfacial Bond Behavior Of Steel Fiber Cement Morter To Concrete

Steel fiber cement mortar reinforce technology is a new method to reinforce the concrete structure. Steel fiber cement mortar is a new composite material which is made by the cement motor with addition of steel fiber. It overcomes shortcomings of ordinary cement mortar, including the low tensile strength, small ultimate elongation and poor crack resistance, instead it has advantages with better bending strength and impulse strength, abrasion resistance, high fatigue strength. Similar to the traditional section increment method, the reinforcement effect of the new reinforce technology is still due to the bonding quality of the new repairing layer and the old concrete. The question that how to avoid a bonding failure occur between the two layers, and make the two materials work together is the key of the widely application of the reinforce technology. The bonding quality of adhesion between steel fiber mortar and concrete is researched in the thesis.Firstly, By the two-sided shearing experiments of concrete species strengthened by steel fiber cement mortar, the influence regularities of the main factors on the shearing property were discussed, such as different interfere treatments of old concrete, strength of concrete and the steel fiber cement mortar. The effect degree of each factor and their interactive effect were analyzed by using double factors variance analysis. The shearing strength formula was fitted by Table Curve 3D, which could provide reference for reinforcement design.Secondly, the tensile behavior of steel fiber cement mortar to concrete was researched by the core-drilling and pull-stripping tests in which interface agent, strength of concrete and steel fiber cement mortar were considered as the affect factors. The effect degree of every factor was analyzed by variance analysis and the range analysis. The test data of shearing strength and the tensile strength were analyzed by regression analysis, and a linear relationship of the two bonding property indicators was acquired.Finally, by using the MATLAB neural net tool kit, the BP artificial neural networks (ANN) predictive models for the interface shearing property and the tensile property between the steel fiber cement mortar and the old concrete were designed. The results of prediction agreed well with the test data both in the two predictive models, and their precision met the needs of engineering practices which showed that the two models were proved to be highly reliable. By using the predictive models, the interface bonding property can be predicted, which could reduce workload, provide a new research method for subsequent experimental study and application.