Study On The Preparation And Properties Of High Resistivity Concrete

Ordinary concrete is a kind of material between the conductor and the insulator.High-resistivity concrete is mixed with some materials in the ordinary concrete to improve its insulation performance.It is widely used in subways and electric power projects.Due to its good compactness and high resistance,it can effectively reduce the problem of stray current caused by corrosion of steel bars in subway projects and can also solve the phenomenon of "stepping electric shock" in power engineering.There is a very broad prospect for development in the future.This paper uses P.O 42.5 cement as the matrix material to investigate the influence of water-cement ratio,cement content,zeolite powder,fly ash,silica fume,polypropylene fiber and other factors on the resistivity of concrete.The results showed that the zeolite powder,fly ash,silica fume and polypropylene fiber all had the effect of increasing the resistivity and the lifting effect was reduced in turn according to the silica fume,fly ash,zeolite powder and polypropylene fiber.Among them,15wt%silica fume is used instead of cement,and the concrete resistivity can reach 3.67 times that of ordinary concrete.Under the condition of certain amount of cement and admixture,orthogonal test was designed and 28d concrete resistivity was used as performance reference index.The optimum mix ratio was selected and optimized to determine the optimal mix ratio of high resistivity concrete.XRD and SEM were used to characterize the composition and microstructure of the concrete.The results show that the concrete prepared according to the experimental optimum mix ratio has a resistivity of 550 ?.m and a compressive strength of 54.7 MPa for 28 days.The internal pores of the concrete are less interconnected and the microstructure is denser.The corresponding hydration products mainly include hydrous calcium silicate gel,calcium aluminum hydrate,and calcium hydroxide.At the same time,the radioactivity,chloride ion content and weather resistance of the high-resistivity concrete were tested.The results showed that the high-resistivity concrete internal exposure and external exposure index were 0.15 and 0.23,respectively,and they all met the requirements of the "Technical requirements for environmental labeling products ready-mixed concrete" standard technology.The required values(lRa ? 0.9,Ir ? 0.9);The corresponding chloride ion content of 0.018590%meets the requirements of GB/T 50010-2010,GB/T 50476-2008 chloride ion content;After simulating the natural environment,the corresponding concrete compressive strength It is 55.2MPa.