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CN-117209200-B - Nano calcium silicate hydrate crystal nucleus early strength agent and preparation method and application thereof

CN117209200BCN 117209200 BCN117209200 BCN 117209200BCN-117209200-B

Abstract

The invention belongs to the technical field of building materials, and particularly relates to a nano calcium silicate hydrate crystal nucleus early strength agent, and a preparation method and application thereof. The preparation method comprises the steps of mixing a crystal nucleus growth inhibitor, an emulsifying agent and water to obtain emulsion, dropwise adding a soluble calcium source aqueous solution and a soluble silicon source aqueous solution into the emulsion under the stirring condition, adding alkali to adjust the pH value to be more than 12, and continuing stirring for a period of time to obtain the aqueous solution. The crystal nucleus particle size of the nano calcium silicate hydrate crystal nucleus early strength agent prepared by the preparation method is mainly distributed at 100-150 nm, so that the early strength of concrete can be remarkably improved, and the later strength of concrete is not reduced.

Inventors

  • LI YANG
  • YAO XIANGYU
  • ZHAO YUXIANG
  • TANG RUIFENG

Assignees

  • 北京建筑材料科学研究总院有限公司
  • 北京金隅集团股份有限公司

Dates

Publication Date
20260512
Application Date
20230825

Claims (8)

  1. 1. The preparation method of the nano calcium silicate hydrate crystal nucleus early strength agent is characterized by comprising the following steps of: (1) Mixing a crystal nucleus growth inhibitor, an emulsifying agent and water to obtain emulsion; The crystal nucleus growth inhibitor is a silane inhibitor and/or an alkyd inhibitor; the silane inhibitor is one or more selected from polymethylhydrosiloxane, polydimethylsiloxane, hexadecyltrimethoxysilane and isobutyl silane; the alkyd inhibitor is one or more selected from stearic acid, oleic acid, citric acid and triethanolamine; (2) Dropwise adding a soluble calcium source aqueous solution and a soluble silicon source aqueous solution into the emulsion under the stirring condition, and then adding alkali to adjust the pH value to be more than 12; (3) Continuously stirring for a period of time to obtain the product; In the step (1), the mass ratio of the crystal nucleus growth inhibitor to the emulsifier is 8-10:1; in the step (1), the mass fraction of the emulsion is 8-12%; In the step (1), the crystal nucleus growth inhibitor, the emulsifier and the water are mixed by stirring at a rotation speed of 1000r/min or more for 20min or more.
  2. 2. The preparation method according to claim 1, wherein in the step (1), the emulsifier is selected from one or more of peregal O-25, AEO-9, OP-7, OP-10, tween-20, tween-80, span-20 and span-80.
  3. 3. The method according to claim 1, wherein in the step (2), the soluble calcium source is one or more selected from the group consisting of calcium nitrate tetrahydrate, calcium formate, calcium acetate, calcium chloride, calcium gluconate, calcium hydrogen phosphate, and calcium lactate; And/or the soluble silicon source is selected from one or more of ethyl orthosilicate, sodium metasilicate pentahydrate, potassium silicate and sodium metasilicate nonahydrate.
  4. 4. The preparation method of claim 1, wherein in the step (2), the mass fraction of the soluble calcium source aqueous solution is 8-12%; and/or in the step (2), the mass fraction of the soluble silicon source aqueous solution is 8-12%; And/or, in the step (2), dropwise adding the soluble calcium source aqueous solution and the soluble silicon source aqueous solution for 25-35 min; and/or in the step (2), the stirring speed is 60-120 r/min.
  5. 5. The method according to claim 1, wherein in the step (3), the stirring speed is 120 to 300 r/min and the stirring time is 25 to 35min.
  6. 6. A nano calcium silicate hydrate crystal nucleus early strength agent, which is characterized by being prepared by the preparation method of any one of claims 1-5.
  7. 7. An early-strength concrete is characterized by comprising cement, sand, stone, the nano calcium silicate hydrate crystal nucleus early-strength agent according to claim 6 or the nano calcium silicate hydrate crystal nucleus early-strength agent prepared by the preparation method according to any one of claims 1-5.
  8. 8. The early strength concrete according to claim 7, wherein the nano calcium silicate hydrate crystal nucleus early strength agent is contained in an amount of 0.5-3 kg per cubic meter of the raw material.

Description

Nano calcium silicate hydrate crystal nucleus early strength agent and preparation method and application thereof Technical Field The invention belongs to the technical field of building materials, and particularly relates to a nano calcium silicate hydrate crystal nucleus early strength agent, and a preparation method and application thereof. Background Along with the continuous promotion of the industrialization of the buildings in China, the mixed precast concrete members and commercial concrete are developed to a great extent. In the production of traditional concrete prefabricated parts, a steam curing mode is required to be adopted to improve the early strength of concrete, shorten the demolding time and improve the turnover efficiency of the template. However, steam curing consumes a large amount of heat energy, so that the production cost is increased, CO 2、SO3, nitrogen oxide and other chamber gases and pollutants are discharged, the environment is polluted, the concrete is easily subjected to thermal damage, and the durability of the concrete is reduced. The early strength of the concrete is also lower due to the incorporation of the large amount of auxiliary cementing material in the commercial concrete. In the engineering, the early hydration rate of the cement is usually accelerated through an early strength agent to promote the development of the early strength of the concrete, and the addition of the traditional early strength agent usually improves the early strength at the expense of the later strength of the concrete, and various negative effects are easily caused, such as the difficult control of the addition amount of the triethanolamine early strength agent, the excessive retarding, the easy corrosion of the reinforcing steel bar caused by the chlorine-containing early strength agent, the decrease of the impermeability and the corrosion resistance of the concrete caused by the sulfate early strength agent, and the deterioration of the durability of the concrete. In recent years, nanomaterials have been considered as an effective way to improve cement-based material properties. The research shows that the inorganic nano particles, especially nano calcium silicate hydrate, can provide additional nucleation sites for the hydration product C-S-H gel when being added into the concrete, shorten the cement induction period and effectively improve the early mechanical properties of the concrete. Meanwhile, the nano calcium silicate hydrate (C-S-H) not only can accelerate cement hydration, but also can compensate early strength reduction caused by the addition of the low-activity auxiliary cementing material, even can achieve the steaming-free effect, and can increase the durability of concrete. It is generally believed that the smaller the particle size of the seed crystal C-S-H particles, the better the early strength effect, however, according to classical nucleation-growth theory, the nano-C-S-H nuclei gradually grow to reduce the early strength effect. In the prior art, polymer is often introduced as a dispersing agent (usually a polycarboxylic acid water reducer) to synthesize a nanocomposite material to inhibit growth of crystal nuclei, but the preparation time is longer, and the preparation time varies from a few hours to a few days, or the crystal nuclei have poor growth inhibition effect. In view of this, the present invention has been made. Disclosure of Invention The invention aims to provide a brand new nano calcium silicate hydrate crystal nucleus early strength agent, a preparation method and application thereof. Specifically, the invention provides the following technical scheme: the invention firstly provides a preparation method of a nano calcium silicate hydrate crystal nucleus early strength agent, which comprises the following steps: (1) Mixing a crystal nucleus growth inhibitor, an emulsifying agent and water to obtain emulsion; The crystal nucleus growth inhibitor is a silane inhibitor and/or an alkyd inhibitor; the silane inhibitor is one or more selected from polymethylhydrosiloxane, polydimethylsiloxane, hexadecyltrimethoxysilane, ethoxytrimethylsilane, hexamethyldisiloxane, n-butylsilane, isobutylsilane and isooctylsilane; The alkyd inhibitor is one or more selected from stearic acid, lauric acid, capric acid, oleic acid, citric acid, tartaric acid, triethanolamine, diethanolamine, monoethanolamine, triisopropanolamine, formic acid and glycol; (2) Dropwise adding a soluble calcium source aqueous solution and a soluble silicon source aqueous solution into the emulsion under the stirring condition, and then adding alkali to adjust the pH value to be more than 12; (3) Continuously stirring for a period of time to obtain the final product. The invention discovers that the silane inhibitor can form a firm isolation layer taking Si-O-Si as a framework with hydroxyl groups on the surface of the hydrated calcium silicate crystal nucleus through dehydration condensation to inhi