Mineral admixture for self-healing of cracks in steam-cured cement-based materials and its preparation

Abstract

The invention relates to a mineral admixture for crack self-healing of a steam-cured cement-based material and preparation of the mineral admixture. The mineral admixture is prepared from the following components in percentage by weight: 35%-50% of an expanding mineral component, 40%-55% of a crystalline mineral component and 5%-10% of a calcium ion source mineral component. The mineral components are weighed in proportion and uniformly mixed, and the mineral admixture is prepared. The mineral admixture has the advantages that the self-healing effect is remarkable, the cost is low, the durability of the steam-cured cement-based material is effectively improved and the like.

Description

technical field [0001] The invention relates to the field of building materials, in particular to a mineral admixture for self-healing cracks of steam-cured cement-based materials and its preparation. Background technique [0002] Steam-cured concrete has the advantages of rapid early strength development and high production efficiency. In the production of prefabricated components, such as sleepers, track slabs, prestressed beams and subway segments in railway engineering structures, steam-cured concrete is used. Practice has shown that while steam curing conditions promote the hydration process of cement concrete, it will also lead to uneven distribution of hydration products, coarse pore structure, volume expansion of concrete, and larger defects in surface concrete than internal concrete. In the production and application practice of cultured concrete, there are problems of high brittleness and easy cracking. The existence and continuous expansion of cracks are the rea...

AI Technical Summary

Problems solved by technology

[0004] Chinese patent CN 103073212 A discloses a mineral admixture for the self-healing of cracks in cement-based materials. The mineral admixture is added to the cement-based material. Insoluble deposits are generated in the cracks of cement-based materials to fill and seal the cracks of cement-based materials and realize the self-healing of cracks in cement-based materials. question

Steam-cured concrete needs high-temperature steam curing after forming, and the high-temperature and high-humidity curing method will cause some mineral materials to undergo chemical reactions during curing, resulting in a significant decrease in the mechanical properties and self-healing properties of concrete

For example, under steam curing conditions, the structure of the hydration product of cement-based materials is loose and porous, and the mechanical properties of the matrix are significantly reduced; It will quickly interact with calcium ions to form calcium silicate hydrate, calcium aluminate hydrate gel and other substances. Although this can improve the early strength, it reduces the self-healing potential of matrix cracks and greatly contributes to the later self-healing of cracks. reduction; when the silicate mineral material described in the patent is added, its imbibition effect will be accelerated under steam curing conditions, so that the volume will be increased by a high factor, causing unnecessary expansion, thereby destroying the matrix; in addition, the patent stated When the self-healing reaction of concrete occurs, the formation of healing products will consume a large amount of calcium ions in the matrix, and the reduction of calcium ions will lead to the decomposition of the original hydration products

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