阅读说明：本技术 一种混凝土晶核早强剂 (Concrete crystal nucleus early strength agent ) 是由 刘子毅 胡凯伟 倪锐 沈学涛 于浩 于 2019-11-14 设计创作，主要内容包括：本发明涉及一种混凝土晶核早强剂,其原料组分及各组分的质量分数为：酰氧基硅烷18％～33％、钙盐5％～15％、纳米纤维2.5％～5.5％、水合硅酸镁0.4％～1.0％、改性聚乙烯醇0.1％～0.5％、水55％～64％。本发明能够有效提高混凝土超早期强度,且对混凝土和易性及后期强度发展无影响,可以有效缩短预制构件脱模时间,成本低廉、性能稳定。(The invention relates to a concrete crystal nucleus early strength agent which comprises the following raw material components in percentage by mass: 18 to 33 percent of acyloxysilane, 5 to 15 percent of calcium salt, 2.5 to 5.5 percent of nano-fiber, 0.4 to 1.0 percent of hydrous magnesium silicate, 0.1 to 0.5 percent of modified polyvinyl alcohol and 55 to 64 percent of water. The invention can effectively improve the ultra-early strength of the concrete, has no influence on the workability and the later strength development of the concrete, can effectively shorten the demoulding time of the prefabricated part, and has low cost and stable performance.)

1. The concrete crystal nucleus early strength agent is characterized by comprising the following raw material components in percentage by mass:

2. the concrete crystal nucleus early strength agent as claimed in claim 1, characterized in that the acyloxysilane is at least one of 3- (methacryloyloxy) propyltrimethoxysilane, 3- (methacryloyloxy) propyltriethoxysilane or 3- (methacryloyloxy) propylmethyldimethoxysilane.

3. The concrete crystal nucleus early strength agent as claimed in claim 1, characterized in that the calcium salt is at least one of calcium formate or calcium lactate.

4. The concrete crystal nucleus early strength agent as claimed in claim 1, characterized in that the diameter of the nano-fiber is 1nm to 50 nm.

5. The concrete crystal nucleus early strength agent as claimed in claim 1, characterized in that the modified polyvinyl alcohol is at least one of aminated nano silica surface grafted polyvinyl alcohol or alkylated nano silica surface grafted polyvinyl alcohol.

Technical Field

The invention relates to a concrete crystal nucleus early strength agent, and belongs to the technical field of concrete.

Background

Concrete is the most used building material in the world at present, and the main advantages of low price, strong bearing capacity and high durability are the concrete. Due to the slow hydration reaction process of the portland cement and the influence of the environmental temperature, the strength of the concrete develops slowly, the strength of the demolished template can be achieved generally within more than 24 hours, the strength within 3 days can only reach 40-50% of the designed strength, and the strength within 28 days can only reach the designed strength. In addition, the brittleness and poor crack resistance are important defects. To overcome these drawbacks of concrete materials, a great deal of research and exploration work has been conducted by scientists and engineers in the field of civil engineering and materials science. In order to improve the early strength of concrete, accelerate the turnover of moulds and improve the production efficiency, the following method is generally adopted: (1) adding an early strength agent: the chlorine salt early strength agent is an inorganic salt early strength agent which is applied earliest, can improve the early strength of concrete, but seriously influences the later strength of the concrete, and is limited in application because the chlorine salt early strength agent contains Cl < - > and is easy to cause steel bar corrosion. The sulfate early strength agent is easy to cause the deterioration of later performance, and white frost is easy to separate out on the surface of concrete, thereby affecting the appearance. (2) The method for reducing the water-cement ratio and improving the cement consumption or using the superfine cement comprises the following steps: the method has the problems that the self-shrinkage of the concrete is greatly increased, the cracking risk is increased, the workability of the concrete is deteriorated due to the low water-cement ratio, the production operation is difficult, the additive consumption is obviously increased, and the production cost is greatly increased. (3) Curing by using high-temperature steam: under the high-temperature steam curing condition, the hydrated crystal size of the cement is large, the brittleness is further increased, and the durability is reduced. In order to overcome the defects of high brittleness and poor crack resistance of concrete, technical measures such as adding fibers and polymer emulsion are generally adopted. However, the fiber is difficult to disperse in the concrete, the working performance of the concrete is seriously influenced, and the manufacturing cost of the concrete is greatly improved. (4) The polymer emulsion can improve the toughness of concrete to a certain extent, but can seriously reduce the compressive strength of the concrete, and the application is limited. In the cement hydration process, calcium silicate gel (C-S-H) is one of the most main hydration products of cement, plays an important role in the strength development and the durability of concrete, prepares and deeply knows the composition and the crystal structure model characteristics of the C-S-H gel, and has important significance in adjusting and controlling the mechanical property and the durability of the concrete. With the development of modern construction technology and the constant research efforts of many experts and scholars on the problems, most experts and scholars consider calcium silicate hydrate gel (CSH) as a method for solving the problems of early strength and later durability of concrete.

The use of nanocrystalline nucleation to improve the early strength of concrete has been reported. Chinese patent CN104402009A discloses a calcium silicate hydrate gel solution early strength agent and a preparation method thereof, wherein the preparation method comprises the following steps: the gel dispersing agent comprises a calcareous material, a siliceous material, a gel dispersing agent and water, wherein the weight ratio of the calcareous material to the siliceous material is 0.3-3: 1, the weight ratio of the water to the total weight of the calcareous material and the siliceous material is 5-30: 1, the mass fraction of the gel dispersant is 0.01-0.50%. The preparation method of the early strength agent comprises the steps of weighing reactants, and respectively preparing sodium silicate and calcium nitrate aqueous solutions; then mixing the two solutions for reaction to obtain a gel mixed solution; then carrying out suction filtration; finally, water and a dispersing agent are added for redispersion. The early strength agent is uniform and stable, convenient to store, high in use convenience degree and good in early strength effect, and can effectively reduce the reaction risk of the alkali aggregate. However, the sodium silicate used for synthesis has a large amount of sodium ions, and the influence of the application durability of concrete is difficult to avoid. Patent CN 107352836A discloses a super-strong crystal nucleus of super-early-strength concrete admixture and a preparation method thereof, which is prepared by compounding and mixing a stabilizer, a dispersant, calcium silicate, triethanolamine, calcium nitrate and water, and the super-strong crystal nucleus comprises the following raw materials: 0.2-0.5% of stabilizer, 0.1-0.5% of dispersant, 8-13% of calcium silicate, 5-8% of triethanolamine, 1-10% of calcium nitrate and the balance of water, wherein the total amount is 100%; under the natural curing condition, the early strength of the concrete can be effectively improved, the turnover of the mould is accelerated, the production efficiency is improved, and the concrete can be cured without steaming. However, the crystal nucleus early strength agent prepared by the method has a short storage period due to unstable complexation of the calcium salt and the triethanolamine, and the stability requirement of more than 6 months is difficult to meet.

Disclosure of Invention

The invention aims to overcome the defects of durability and unstable storage caused by overlarge alkali content of the crystal nucleus early strength agent, and provides the concrete crystal nucleus early strength agent which is alkali-free, chlorine-free, high in stability, capable of improving the ultra-early strength of concrete and shortening the demoulding time of a prefabricated part.

The technical scheme of the invention is as follows: the concrete crystal nucleus early strength agent is characterized by comprising the following raw material components in percentage by mass:

preferably, the acyloxysilane is at least one of 3- (methacryloyloxy) propyltrimethoxysilane, 3- (methacryloyloxy) propyltriethoxysilane, or 3- (methacryloyloxy) propylmethyldimethoxysilane.

Preferably, the calcium salt is at least one of calcium formate or calcium lactate. Preferably, the diameter of the nanofiber is 1nm to 50 nm.

Preferably, the modified polyvinyl alcohol is at least one of aminated nano-silica surface grafted polyvinyl alcohol or alkylated nano-silica surface grafted polyvinyl alcohol.

And (3) placing the weighed raw materials into a reaction kettle, and uniformly stirring and mixing to obtain the concrete crystal nucleus early strength agent.

Has the advantages that:

1. the concrete crystal nucleus early strength agent prepared by the invention has the advantages of easily-mixed raw materials, simple process, effective stabilization of the anchoring and anti-settling of calcium salt through the synergistic effect of the emulsifier, the magnesium silicate monohydrate and the nano-fiber, and the stable storage life of the concrete crystal nucleus early strength agent can reach 12 months.

2. The crystal nucleus type concrete early strength agent prepared by the invention has a unique microfiber structure and strong polar groups, under the action of crystal nucleus induction and nucleation potential barriers, cement particles are arranged more compactly, the early strength and the later strength of concrete are obviously enhanced, the demolding time of a prefabricated part is obviously shortened, and the adaptability to concrete is good.

3. The concrete crystal nucleus early strength agent prepared by the invention has excellent compatibility when being compounded with other water reducing agents in concrete application, and has no precipitation phenomenon.

Detailed Description