Anti-cracking steam-curing-free ultra-high-strength high-toughness concrete and preparation method thereof

Abstract

The invention discloses anti-cracking steam-curing-free ultra-high-strength high-toughness concrete. The anti-cracking steam-curing-free ultra-high-strength high-toughness concrete is prepared from cement, fly ash, silica fume, a mineral activator with cementing property, gravel, river sand, steel fibers, a polymer emulsion, water and a shrinkage-reducing super-dispersing admixture, wherein the mineral activator with cementing property comprises waste prefabricated concrete set cement crystal seeds and desulfurized gypsum. By using the mineral activator with cementing property in the concrete, high-temperature steam curing and pressurized steam curing systems adopted in the ordinary ultra-high-performance concrete are eliminated; and the shrinkage-reducing super-dispersing admixture having the functions of super-dispersing cement, reducing shrinkage, decreasing viscosity and the like is adopted to enable the hydration activity of cement to give a full play so that the strength of the concretes has no obvious change after cement usage is decreased by about 10%; and meanwhile, the mineral activator and the admixture can effectively suppress the shrinkage of concrete. The concrete prepared by the preparation method is higher in strength, toughness and shrinkage resistance, low in cost and simple in preparation method and has important practical application value.

Description

technical field [0001] The invention belongs to the field of building materials, and in particular relates to a crack-resistant, steam-cured, ultra-high-strength, high-toughness concrete and a preparation method thereof. Background technique [0002] Reactive powder concrete (RPC) is a high-strength, low-porosity ultra-high performance concrete. The basic formulation principle of RPC is: the material contains few defects such as micro-cracks and pores, and can obtain a large bearing capacity determined by its constituent materials, and has particularly good durability. According to this principle, the preparation of RPC generally takes the following measures: remove coarse aggregate to improve homogeneity; optimize particle gradation, pressurize before and during solidification to improve the compactness of the mixture; heat curing after solidification Improves microstructure. Due to its extremely excellent mechanical properties and ultra-high durability, activated powder ...

AI Technical Summary

Problems solved by technology

[0003] However, ultra-high-performance concrete has the following problems: 1) Raw materials are not easy to obtain and are expensive, and concrete generally needs to be cured at high temperature or under pressure for molding and curing, which is complicated in process, high in energy consumption, and high in maintenance costs; 2) The water-binder ratio of ultra-high performance concrete is low, the amount of cementitious material is large, the content of cement and silica fume is high, the shrinkage of concrete is large, and the autoclaved curing system is bound to further increase the shrinkage, and the concrete is easy to crack; 3) Studies have shown that, About 15-30% of the cement in concrete cannot be effectively dispersed and cannot be hydrated, so it can only be used as aggregate in concrete, and the hydration rate of cement in ultra-high performance concrete with extremely low water-binder ratio must be lower; 4) The amount of mineral admixtures such as fly ash and slag powder in modern concrete is generally large, but their activity has not been effectively stimulated

These problems limit the popularization and application of reactive powder concrete in practical engineering

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