Shrinkage-reducing anti-cracking pavement cement concrete and preparing method thereof

Abstract

Shrinkage-reducing anti-cracking pavement cement concrete and a preparing method thereof are disclosed. The cement concrete is prepared from water, cement, fly ash, basalt fibers, light aggregate, broken stone, sand and a water reducing agent in a mass ratio of (180-200):(400-410):(40-50):(2.65-5.3):(229-286):(465-559):(830-850):(4.1-4.5). The light aggregate is uniformly dispersed in the concrete, the concrete is not liable to crack, adhesive force between the fibers and cement slurry is high, microcrack development is slow, and the concrete has high fatigue resistance and tension resistance.

Description

technical field [0001] The invention belongs to the technical field of concrete, and relates to a shrinkage-reducing and anti-cracking pavement cement concrete and a preparation method thereof. Background technique [0002] Cement concrete pavement is the main structural form of existing pavement in my country. However, it is easy to shrink and crack in the early stage, which reduces its bearing capacity, accelerates the erosion of harmful substances, and seriously affects the durability of concrete structures. In recent years, especially the development of various chemical admixtures (such as expansion agents, shrinkage reduction and anti-cracking agents, etc.), although the shrinkage and cracking of concrete can be reduced to a certain extent, the incorporation of chemical admixtures tends to reduce the degree of hydration inside the concrete and make it worse. Affect its tensile strength, and it is not easy to control during construction. Therefore, how to reduce the ear...

AI Technical Summary

Problems solved by technology

[0004] However, the commonly used shrinkage-reducing and anti-cracking concrete also has certain limitations: (1) For concrete that only relies on lightweight aggregates for internal curing, due to the porous nature of lightweight aggregates, it also determines that its density is lower than that of ordinary aggregates. low feature

When a certain amount of lightweight aggregate is mixed into ordinary concrete, it will float up, and the ordinary aggregate will sink due to its high density, which eventually leads to uneven dispersion of light aggregate in the concrete.

In addition, too much light aggregate leads to a decrease in the strength of the concrete. When the shrinkage stress of the concrete reaches a certain level and cracks occur, the cracks will develop along the weak interface of the light aggregate, so it is easy to form cracks during the cement hardening process.

(2) Similarly, for concrete reinforced only by fibers, because the surface of basalt fibers is hydrophilic, part of the water is absorbed with the incorporation of fibers in the early stage, which reduces the effective water-cement ratio of concrete and increases the shrinkage of concrete, while The moisture adsorbed on the surface of the fiber has not fully hydrated with the cement, and the bonding between the fiber and the cement slurry is weak, so the effect of the basalt fiber on shrinkage is not reflected

In addition, although basalt fibers have a crack-resistance and toughening effect on concrete, this is passive and static crack-resistance, and the fatigue resistance of the fiber itself is a process of continuous consumption. Once micro-cracks appear in the concrete, the reinforcement at the cracks The weak point of stress concentration will appear in the fiber, and the external load will accumulate a large amount of work and transform it into fiber strain energy and friction loss at the interface. As a result, the fiber itself will be broken or pulled out, micro-cracks will develop rapidly, and the fatigue resistance of concrete Big discount

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