Experimental Study On Mechanical Electrical Properties And Carbonization Durability Of Carbon Fiber Cement Based Materials From Iron Tailings

Carbon fiber reinforced cement-based composites is a new kind of smart material,and its application in engineering can facilitate the health monitoring of structure.Iron tailing is a kind of industrial waste,if not properly treated will cause harm to soil and water quality.In this paper,by adding an appropriate amount of iron tailings into CFRC,iron-tailings carbon fiber reinforced cement-based composites were prepared to improve the mechanical properties and pressure sensitive properties of the specimens.In addition,the changes of mechanical properties,pressure-sensitive properties and durability properties in carbonization environment are studied through experiments.The main research work and conclusions are as follows:(1)Referring to the existing test data and results of the research group,78 Io T-CFRC cube test blocks with 15%,30%,45% iron tailings replacement rate and 0.2%,0.4%,0.6%carbon fiber content were designed and prepared,and 39 polystyrene test blocks were designed and prepared.The mechanical properties of IOT-CFRC were studied through mechanical property tests.The influence of different content of iron tailings and carbon fiber on the mechanical properties of IOT-CFRC was analyzed,and the corresponding change law was summarized.The constitutive equation between different content of iron tailings and its main mechanical properties was obtained.The results show that the main mechanical properties of CFRC are improved after adding iron tailings with different substitution rates.Especially when the carbon fiber content is 0.4% and the substitution rate of iron tailings is 30%,the cubic compressive strength,splitting tensile strength and axial compressive strength of the material are increased by about 20%,16.9% and 22.8%compared with CFRC,respectively.It can be seen that the improvement effect is more obvious.(2)A total of 390 Io T-CFRC cubes with the same substitution rate and carbon fiber content as the iron tailings mentioned above were designed and fabricated,and the rapid carbonization simulation tests with ages of 3D,7d,14 d,28d and 56 d were conducted respectively.Meanwhile,the mechanical properties of Io T-CFRC and the carbonization depth prediction model were analyzed.The influence of different iron tailings replacement rate and carbon fiber content on the main mechanical properties and carbonation depth of Io T-CFRC was studied.The change law of main mechanical properties,carbonation depth evolution mechanism and evolution law of Io T-CFRC under different carbonation ages were analyzed,and the corresponding prediction model of IOT-CFRC carbonation depth was established.The results show that the compressive strength and splitting tensile strength of Io T-CFRC are high under the carbonization age conditions and the substitution rate of 0.4% carbon fiber and 30% iron tailings,indicating that the carbonization depth of Io T-CFRC at different carbonization ages is shallow under the substitution rate of 0.4%carbon fiber and 30% iron tailings.Its carbonization resistance is good.(3)A total of 165 Io T-CFRC prisms were designed and manufactured,and the force-voltage sensitive properties of Io T-CFRC were tested under different iron tailings replacement rates,different carbon fiber content and different carbonization ages.The effect of different carbon fiber content and iron tailings replacement rate on the isobaric performance of Io T-CFRC is studied.The corresponding resistivity rate-compressive stress curve is fitted,and the corresponding pressure-resistivity change rate equation is established.The results show that,compared with ordinary cement-based materials,the force-voltage sensitive property of CFRC can be significantly improved by adding different amounts of carbon fiber,and the pressure sensitive property of CFRC with 0.4% carbon fiber content is improved more obviously.The force-voltage sensitive performance of Io T-CFRC is significantly higher than that of CFRC under the same conditions when the iron tailings with different replacement rates are added.When the carbon fiber content is0.4% and the iron tailings replacement rate is 30%,the force-voltage sensitive performance of IOT-CFRC is the best.(4)Using computed tomography(CT)technology,this paper analyzes the different carbon fiber content,iron tailings,replacement rate,the IOT under different carbonization age-microstructure change law of CFRC,analyzes the various working conditions is IOT-the general rule of CFRC porosity change,and explained the macro mechanical properties test results,the force-voltage sensitive performance improvement and improve the main mechanism of durability of carbide.The results show that with the increase of iron tailings substitution rate,the internal porosity of Io T-CFRC decreases first and then increases,but with the increase of carbonation age,the internal porosity of Io T-CFRC decreases,and the early decline rate is faster,and the later decline rate is slower.Relatively speaking,when the replacement rate of 30% iron tailings and the carbon fiber content is 0.4%,the porosity of Io T-CFRC is lower than that of other working conditions at different carbonation ages in the test,indicating that the internal microstructure of Io T-CFRC is relatively dense at this time,and the change rate of force-resistivity in the macroscopic pressure sensitive performance test is also more obvious.