Core Drilling And Pull-off Test Of Interfacial Behaviors Between Fiber Cement Mortar And Concrete

At present, concrete structure is widely use because it‘s property of easily obtained, can be molded, good durability and economy applicable. Due to the improper of design, construction and use, and influence of natural factors, a large number of concrete structures are in need of reinforcement. The method based on fiber cement mortar reinforcement is economical and widely use, the reinforcement effect of this reinforce technology is still due to the bonding quality of the new r epairing layer and the old concrete. Current research on bonding performance between fiber cement mortar and concrete interface was relatively few, and the research methods have limitations and can‘t apply to the in site bond quality evaluation. We use the core drilling and pull-off test to study the interfacial behaviors between fiber cement mortar and concrete. The main contents and conclusions are as follows:(1) Simulate the actual reinforcement situation, three kind of fiber cement mortar(polyvinyl alcohol fiber, polypropylene fiber and steel fiber) were respectively used to reinforce plain concrete blocks of different intensity levels. According to mix proportion, each fiber cement mortar has 9 intensity levels, that M20、M30、M40、M50、M60、M70、M80、M90、M100. When reinforce plain concrete block, it is making accordingly test cubes. The test cubes and reinforced specimen were p laced under the same condition. The core drilling and pull-off method are used to test the bond strength between fiber cement mortar and concrete. According to the comparative analysis of the bond strength and the types of fiber cement mortar, the compressive strength of fiber cement mortar, the compressive strength of concrete, we get the trend of bond strength to three factors.(2) Using analysis of variance to analyze the significance for each factor on the bond strength. The result show that the effect of fiber type to the bond strength is not significant, the effect of compressive strength of fiber cement mortar and concrete on the bond strength are significantly. The effect of interaction between the type of fiber and compressive strength of fiber cement mortar on the bond strength was not significant, the effect of interaction between the type of fiber and compressive strength of concrete on the bond strength are significantly. Using a linear fit to the relationship between the pull-off result and compressive strength of mortar and concrete, the fitting results correlated well.(3) MATLAB neural network model of core drilling and pull-off strength are established, the predictions of this model are in good agreement with the measured values, the model are higher precision, high reliability. The result showed that the use of neural network to predict the interfacial bonding properties is feasible, broader applicability of neural network model may establish in future research.