An admixture for improving crack resistance and thixotropic performance of super high-rise pumped concrete

Abstract

The invention belongs to the field of building materials, and in particular relates to an admixture for improving the anti-cracking and thixotropic properties of super-high-rise pumped concrete. The admixture is composed of silica fume, fly ash microbeads, superfine limestone powder, modified montmorillonite and microcrystalline cellulose modified superabsorbent resin fiber. Based on the theory of close packing of particles, the invention uses silica fume, fly ash microbeads and ultra-fine limestone powder to optimize the particle composition of super-high-rise pumped concrete cementitious materials, and utilizes the strong water absorption and slow penetration of modified montmorillonite to release water Function and microcrystalline cellulose modified superabsorbent resin fiber surface hydrophilic and super-adsorption characteristics, improve the thixotropic performance and crack resistance of concrete, reduce the risk of concrete pumping pipe plugging and construction difficulty.

Description

technical field [0001] The invention belongs to the field of building materials, and in particular relates to an admixture for improving the anti-cracking and thixotropic properties of super-high-rise pumped concrete. Background technique [0002] The pumping distance of concrete in super high-rise buildings is long, and the structural reinforcement is dense, and the cross-sectional size of some structures is large. High-rise pumped concrete is required to have excellent flow properties, thixotropic properties and crack resistance. [0003] However, the following problems are common in super high-rise pumped concrete at present: (1) The amount of cementitious material used in super high-rise pumped concrete is relatively high, the particle gradation of the cementitious material system is unreasonable, the concrete has a large thermal insulation temperature rise, large shrinkage, and is easy to crack; ( 2) Due to the long pumping distance, the loss of working performance dur...

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Problems solved by technology

[0003] However, the following problems are common in super high-rise pumped concrete at present: (1) The amount of cementitious material used in super-high-rise pumped concrete is relatively high, the particle gradation of the cementitious material system is unreasonable, the concrete has a large adiabatic temperature rise, large shrinkage, and is easy to crack; ( 2) Due to the long pumping distance, the loss of working performance during the concrete pumping process is large. If the pump is stopped for a long time, it is easy to cause pipe blockage. After the pump is pumped, the fluidity of the concrete is poor, and some construction sites such as dense steel bars, certain slopes, and special shapes Concrete that cannot meet the requirements of engineering construction and has a large loss of work performance is prone to quality problems such as honeycomb, pockmarked surface, and exposed ribs; (3) Due to its structure and service environment, concrete for super high-rise buildings requires concrete to have good anti-corrosion properties. However, the commonly used anti-cracking method is fiber crack resistance. However, simply adding fibers will disperse unevenly in high-strength concrete with low water-binder ratio, seriously affecting the working performance of concrete, and it is difficult to achieve its self-compacting and high-strength concrete. Super high-rise pumping

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