The Study On CFRC Mechano-Electric Properties And Size Effect

Carbon fiber reinforced cement based composite material is ordinary concrete, mortar or cement substrate, which add carbon fiber as conductive composition and other additives, so that the concrete into a certain temperature-sensitive smart and intelligent materials (known as Carbon Fiber Reinforced Cement based Composites referred to CFRC). It not only brought with fiber-reinforced high tensile, compressive, flexural strength and toughness, also has a relatively small force of resistance and superior performance of the motor and other sensitive. Mintel use of such force of the motor can be achieved on the concrete structure of stress during service monitoring and damage assessment. For CFRC sensitivity of force motor is relatively mature, but the motor force for the CFRC sensitive aspects of size effect has been relatively scarce.For these problems, in Jiangxi Province Natural Science Foundation of China (2009GZC0013) funded by members of the force CFRC similar geometry and size effects the electrical properties of the system. The main work of this paper is as follows:(1) Access to the research and the size effect CFRC theoretical literature on the basic theory and the results have been summarized, and based on the experimental design.(2) Design and production of the C group of 18 specimens geometrically similar cube CFRC. They studied under cyclic loading with the size variation of pressure sensitive and the same stress conditions of stress, strain and resistivity changes in the relationship between the study found the sensitivity of CFRC sensitivity coefficients K66.7 <K100 < K150, CFRC the sensitivity of the increase with the size increase; CFRC varistor has a good repeatability.(3) Design and production of the A, B groups of 36 specimens geometrically similar cube CFRC. Them through the splitting tensile strength, compressive strength tests were found with the strength of the specimen size decreases, CFRC there was an obvious size effect. Meanwhile, a cube of side length 150mm as the standard sample specimen, the specimen side length of 100mm and splitting tensile strength, compressive strength size effect coefficient: 0.94 and 0.83, while the concrete is: 0.95 and 0.85 , due to the dispersion of test data and test some existing non-standard operations, the proposed size effect of the strength of CFRC desirable and concrete the same conversion factor value.(4) Combined with Bazant size effect caused by the energy release theory of splitting tensile strength and compressive strength of CFRC's size effect analysis parameters by fitting the experimental data and deduced the corresponding size effect under the law of a unified formula obtained CFRC specimen size and strength relationship. At the same time until the destruction of monotonic compression of the sensitivity of CFRC specimens studied, the study found there is failure process CFRC three stages: the linear growth phase resistivity, resistivity of dynamic equilibrium stage, the rapid growth stage resistance.(5) In order to be applied to practical engineering CFRC, the paper produced six beams of ordinary reinforced concrete trough, and then CFRC material embedded in the slot. Way through them until the damage load test, obtained the resistivity changes CFRC - load curves, the resistivity change - across the deflection curve, resistivity changes - strain curve, the use of smart features to achieve the CFRC bending line monitoring component.