A surface-modified ultra-fine steel fiber reinforced high-impedance ultra-high performance concrete and its preparation method

Abstract

The invention discloses surface-modified ultrafine steel fiber reinforced high-impedance ultrahigh-performance concrete and a preparation method thereof, and belongs to the technical field of buildingmaterials. The ultrahigh-performance concrete comprises the following components in parts by mass: 50-300 parts of surface-modified ultrafine steel fiber, 500-1500 parts of cement, 50-500 parts of amineral admixture, 1000-1800 parts of fine aggregate, 5-40 parts of a chemical admixture and 150-650 parts of water. The preparation method comprises the following steps: preparing a nanometer silicondioxide modifier; performing surface modification on ultrafine steel fiber; stirring and curing concrete. Through modification of growing SiO2 on the surface of the ultrafine steel fiber, morphologically, the surface roughness is improved and a friction coefficient between the fiber and a matrix is increased, and chemically, by virtue of high volcanic ash activity of nanometer SiO2, secondary hydration is performed on the nanometer SiO2 and a cement hydration product Ca(OH)2 to produce calcium silicate hydrate gel C-S-H so as to improve a weak interfacial region; the flexural strength of thesurface-modified ultrafine steel fiber reinforced high-impedance ultrahigh-performance concrete reaches 25MPa or above, and the electrical resistivity thereof reaches 20,000 ohm.cm or above.

Description

technical field [0001] The invention belongs to the technical field of building materials, and in particular relates to a surface-modified ultra-fine steel fiber reinforced high-impedance ultra-high-performance concrete and a preparation method thereof. Background technique [0002] Since the advent of high-performance concrete in the 1990s, it has become a new type of cement-based building material that has attracted much attention due to its excellent mechanical properties and durability, and has been increasingly used in engineering practice. In recent years, with the construction of major infrastructure such as long-span bridges and high-speed railways, ultra-high performance concrete with higher strength and durability has been more and more researched and applied. Ultra-high performance concrete generally improves the shortcomings of traditional concrete such as low flexural strength, easy cracking, and fatigue damage by adding fibers and using the bridging effect of f...

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Problems solved by technology

[0005] The purpose of the present invention is to solve the problems of low impedance and stray current leakage in existing steel fiber concrete, and provide a surface-modified ultra-fine steel fiber reinforced high-impedance ultra-high performance concrete and its preparation method. The surface used in raw materials The modified ultra-fine steel fiber is based on the steel fiber for ordinary concrete, and the surface has no more than 5000nm nano-SiO with hydration reaction activity. 2 , can react with the cement matrix in a controllable degree, while improving the bonding strength of the interface with the cement, it also plays a role in separating the steel fibers from direct contact with the conductive core, and it is difficult for the steel fibers to form at a higher content Conductive path, to obtain high strength and maintain high impedance at the same time, can be used in reinforced concrete structures, especially high-speed rail, subway, etc. to reduce the leakage and conduction of stray current, so as to avoid accelerated corrosion of reinforced concrete components

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