Bridge self-compaction anti-crack bare concrete prepared by utilizing high fine powder content machine-made sand

Abstract

The invention discloses a bridge self-compaction anti-crack bare concrete prepared by utilizing high fine powder content machine-made sand. The bridge self-compaction anti-crack bare concrete is prepared from cement, activated fly ash microbeads, silica fume, an expanding agent, machine-made sand, gravel, a light-weight porous aggregate, a high-performance additive and water. The bridge self-compaction anti-crack bare concrete provided by the invention adopts the high fine powder content machine-made sand to replace common natural river sand, utilizes the activated fly ash microbeads and the silica fume for adjusting the viscosity and the fluidity of the concrete so as to improve the homogeneity of a concrete slurry, and further additive is used for reducing the gas content of the concrete, so that a working performance and a fluidity keeping performance of the concrete are improved; meanwhile, the expanding agent and the light-weight porous aggregate are combined, so that the volume stability and an anti-early-age cracking behavior of the bare concrete can be effectively improved. The self-compaction anti-crack bare concrete obtained through the invention has wide adaptability on different fine powder content machine-made sand, excellent working performance, mechanical property, volume stability performance and anti-cracking ability, uniform appearance and color, and better mirror surface effect.

Description

technical field [0001] The invention belongs to the field of building materials, and in particular relates to a bridge self-compacting anti-cracking clear-faced concrete prepared by utilizing machine-made sand with high fine powder content and a preparation method thereof. Background technique [0002] With the development of society, the construction of urban bridges must not only meet the requirements of service performance and service life, but also meet the characteristics of aesthetics and adaptability to the environment. Therefore, the use of high-performance fair-faced concrete is an inevitable trend in the development of modern bridge construction. Usually, natural river sand is required to prepare high-performance fair-faced concrete for bridges. However, in recent years, the implementation of national supply-side reforms has placed higher and higher requirements on resource conservation and environmental protection in the building materials industry. In order to pro...

AI Technical Summary

Problems solved by technology

[0003] Machine-made sand is artificially crushed, and some fine stone powder and mud powder with a particle size of ≤0.75 μm will inevitably be introduced during the production process. The concrete prepared by this method has a large amount of adsorption of admixtures, and the concrete has poor workability and homogeneity. Concrete is prone to bottoming and bleeding, and the shrinkage of concrete is significantly increased, and it is easy to crack in the early stage. For this, the national standard "Technical Specifications for Highway Bridge and Culvert Construction" JTG TF50-2011 has made restrictions on the content of stone powder in machine-made sand for concrete

However, the measures of washing machine-made sand to remove fine powder will seriously pollute the environment and increase the cost of concrete raw materials and project cost

At the same time, the density of steel bars at the bottom of the box girder and T-beam is high, and it is difficult to vibrate the concrete in the area where the steel bars are dense. If it is too large, it is easy to cause cracking, exacerbate external corrosion, corrode steel bars, and reduce the service life of the bridge

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