A kind of C30 self-compacting micro-expansion steel pipe concrete and its preparation method

Abstract

The invention discloses a C30 self-compaction microexpanded concrete-filled steel tube and belongs to the field of building materials. The C30 self-compaction microexpanded concrete-filled steel tube is prepared by taking cement, coal ash, composite expansion agents, gravel, river sand, tackifying plasticity-maintaining ultra-dispersed additive, internal maintaining materials, micro-grade modified degreasing cotton cellulose and water as raw materials. The number of binding materials adopted in the C30 self-compaction microexpanded concrete-filled steel tube is small, and the C30 self-compaction microexpanded concrete-filled steel tube has the advantages of being good in self-compaction performance, low in gas content and high in durability, being slightly expanded and the like, is suitable for compact pouring of intensely reinforced large-pipe-diameter thin-wall steel tube concrete-filled steel tube underwater piles with complex shapes and a small section size, string tube pumping pouring of upper and lower concrete-filled steel tubes of concrete-filled steel tube truss bridges and high-throwing vibration-free pouring of concrete-filled steel tube pier studs. The problem of disengaging of the concrete-filled steel tube can be effectively solved, and wide application prospects are achieved.

Description

technical field [0001] The invention belongs to the field of building materials, and in particular relates to a C30 self-compacting micro-expansion steel pipe concrete and a preparation method thereof. Background technique [0002] C30 self-compacting micro-expansion concrete-filled steel tubes are mainly used in large-diameter thin-walled concrete-filled steel tube underwater piles, upper and lower concrete-filled steel tube chords of concrete-filled steel tube truss bridges, and concrete-filled steel tube piers. Among them, concrete-filled steel pipe underwater piles are difficult to pour due to the dense reinforcement and large pouring depth, so the concrete-filled steel pipe concrete is required to have good fluidity, cohesion, low air content, and micro-expansion. If the performance of the concrete fails to meet the design and construction requirements, it is easy to cause problems such as broken piles, insufficient filling and voiding. Concrete-filled steel tube pier ...

AI Technical Summary

Problems solved by technology

Relatively speaking, the quality of cementitious materials in C30 concrete is less, and the cohesiveness of freshly mixed concrete is poor. It is difficult to achieve the high fluidity requirements of self-compacting concrete in order to completely wrap the aggregate in the slurry.

In practice, viscosifying components are usually introduced to improve the water retention by increasing the viscosity of cement paste, but the addition of viscosifying components changes the interfacial tension of the slurry, which brings additional air-entraining effect, which will further increase the air content of concrete. The increase of , affects the service characteristics of CFST

At the same time, steel pipe self-compacting concrete has a larger amount of cementitious material, sand rate, and water-binder ratio than ordinary concrete, and a smaller amount of coarse aggregate and particle size, which is prone to large temperature shrinkage and self-shrinkage, resulting in a gap between the steel pipe and the core concrete. "Debonding", affecting the synergy of the structure and shortening the service life

Common expansion agents are added to compensate for concrete shrinkage. Since the steel tube core concrete is in a moisture-proof and sealed environment, the water supply in the later period is insufficient. The expansion rate of commercially available expansion agents is too fast in the early stage, and the stability is poor. The problem of uncontrollable expansion behavior, it is difficult to match the requirements of the coordinated development of strength and expansion, and the bearing capacity of the deteriorated structure

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