阅读说明：本技术 一种液体无碱速凝剂及其制备方法 (Liquid alkali-free accelerator and preparation method thereof ) 是由 陈世学 刘允伟 邹锋 廖思淘 陈华君 于 2019-11-25 设计创作，主要内容包括：本申请涉及混凝土外加剂领域,具体涉及一种液体无碱速凝剂及其制备方法。所述液体无碱速凝剂通过高浓度的Al<Sup>3+</Sup>浓度形成络合物,显著提升混凝土的凝结速度,另外通过F<Sup>-</Sup>和增加高浓度Al<Sup>3+</Sup>溶液的稳定,并通过其他添加剂增强混凝土的早期强度。本申请所述液体无碱速凝剂在符合检测标准的低掺量的情况下即可大幅提升混凝土的和易性,该液体无碱速凝剂原料易得,生产方便,掺量少,并在生产中不产生污染,因此具备很好的经济价值和环保价值。(The application relates to the field of concrete admixtures, in particular to a liquid alkali-free accelerator and a preparation method thereof. The liquid alkali-free accelerator is prepared by passing high-concentration Al 3+ The concentration forms a complex, the setting speed of the concrete is obviously improved, and in addition, F passes through ‑ And increasing high concentration of Al 3+ The solution is stable and the early strength of the concrete is enhanced by other additives. The liquid alkali-free accelerator can greatly improve the workability of concrete under the condition of low doping amount meeting the detection standard, and has the advantages of easily obtained raw materials, convenient production, small doping amount and no pollution in production, thereby having good economic value and environmental protection value.)

1. A liquid alkali-free accelerator which is characterized by comprising the following components: fluoride, organic amine, silica sol, sulphoaluminate, amide and water; wherein the fluoride is AlF₃。

2. The liquid alkali-free accelerator according to claim 1, wherein the organic amine is (HOCH)₂CH₂)₂NH and/or (HOCH)₂CH₂)₃And N accounts for 5-8% of the liquid alkali-free accelerator.

3. The liquid alkali-free accelerator according to claim 1, wherein the thioaluminate is Al₂(SO₄)₃The mass percentage of the alkali-free accelerator in the liquid alkali-free accelerator is 35-38%.

4. The liquid alkali-free accelerator according to claim 1, wherein the amide is polyacrylamide, and the mass percent of the amide in the liquid alkali-free accelerator is 0.01-0.03%; the molecular weight of the polyacrylamide is 150-250 ten thousand.

5. The liquid alkali-free setting accelerator according to claim 1, wherein the silica sol is present in the liquid alkali-free setting accelerator in an amount of 0.1 to 0.2% by mass, and the fluoride is present in the liquid alkali-free setting accelerator in an amount of 6 to 8% by mass.

6. A method for preparing a liquid alkali-free accelerator, which is the liquid alkali-free accelerator described in any one of claims 1 to 5, comprises the following steps:

1) adding H into a reaction vessel₂O, adding fluoride while stirring;

2) adding organic amine and silica sol;

3) adding an amide;

4) adding sulphoaluminate.

7. The method for producing a liquid alkali-free accelerator according to claim 6, characterized in that: the reaction time of the step 1) is 25-35 min.

8. The method for producing a liquid alkali-free accelerator according to claim 6, characterized in that: the reaction time of the step 2) is 35-45 min.

9. The method for producing a liquid alkali-free accelerator according to claim 6, characterized in that: the reaction time of the step 3) is 15-25 min.

10. The method for producing a liquid alkali-free accelerator according to claim 6, characterized in that: the reaction time of the step 4) is 4-5 h; and 4) observing whether the product is clear and transparent without precipitates after the step 4) is finished, and if not, continuing to react for 30 min.

Technical Field

The application relates to the field of concrete admixtures, in particular to a liquid alkali-free accelerator and a preparation method thereof.

Background

The liquid alkali-free accelerator is an additive used for sprayed concrete, and can obviously shorten the setting and hardening time of the concrete. Compared with the traditional alkaline powder and alkaline liquid accelerating agent, the alkaline content of the accelerating agent is almost zero and no Cl is generated^-The pH value is 3.0-5.0, and the construction can be effectively reducedThe alkali-free liquid accelerator has the advantages of fully dispersing in the mixture, low dust concentration in air during construction, improving the strength of sprayed concrete and avoiding the large fluctuation of the quality of the sprayed concrete, and thus gradually replaces the traditional accelerator in the existing market.

The liquid alkali-free accelerator in the prior market is usually prepared by reacting and mixing sulphoaluminate and other additives, solvents and auxiliaries, wherein Al is³⁺The content of (a) substantially determines the performance of the liquid alkali-free accelerator. Therefore, the technical development direction in the market is: the stable high Al is prepared under the premise of low cost and low pollution³⁺The concentrated liquid alkali-free accelerator also has to have good adaptability with cement common in the market.

Disclosure of Invention

The invention provides a liquid alkali-free accelerator which is characterized by comprising the following components: fluoride, organic amine, silica sol, sulphoaluminate, amide and water; wherein the fluoride is AlF 3.

Further, the organic amine is (HOCH2CH2)2NH and/or (HOCH2CH2)3N, and the mass percent of the organic amine in the liquid alkali-free accelerator is 5-8%.

Further, the sulphoaluminate is Al2(SO4)3, and the mass percentage of the sulphoaluminate in the liquid alkali-free accelerator is 35-38%.

Further, the amide is polyacrylamide, and the mass percent of the amide in the liquid alkali-free accelerator is 0.01-0.03%; the molecular weight of the polyacrylamide is 150-250 ten thousand.

Further, the mass percent of the silica sol in the liquid alkali-free setting accelerator is 0.1-0.2%, and the mass percent of the fluoride in the liquid alkali-free setting accelerator is 6-8%.

The application also provides a preparation method of the liquid alkali-free accelerator, which comprises the following steps:

1) adding H2O into a reaction container, and adding fluoride while stirring;

2) adding organic amine and silica sol;

3) adding an amide;

4) adding sulphoaluminate.

Further, the reaction time of the step 1) is 25-35 min.

Further, the reaction time of the step 2) is 35-45 min.

Further, the reaction time of the step 3) is 15-25 min.

Further, the reaction time of the step 4) is 4-5 h; and 4) observing whether the product is clear and transparent without precipitates after the step 4) is finished, and if not, continuing to react for 30 min.

The liquid alkali-free accelerator contains high-concentration Al³⁺By means of high concentrations of Al in the case of low doping levels³⁺The setting speed of concrete can be obviously improved, the use of the liquid alkali-free accelerator can obviously increase the early strength and the hourly strength increasing rate of the concrete, and the concrete using the liquid alkali-free accelerator also has the advantages of low rebound and no strength loss after the rebound, and meets the standard requirement of GBT 35159-2017. The preparation method of the liquid alkali-free accelerator adopts common materials, the reaction heat release can make the reaction process spontaneously proceed under the action of organic amine, and external heating or pressurization is not needed, so that the preparation method has the advantages of low cost and simple process, and in addition, no waste gas and waste water are generated in the preparation process, so the preparation method also has the advantages of environmental protection and no pollution.

Detailed Description

In order that those skilled in the art will better understand the technical solutions of the present invention, the present invention will be further described in detail with reference to the following embodiments.

The invention provides a liquid alkali-free accelerator, which is an additive in concrete accelerators and is mainly divided into a split accelerator and a liquid accelerator according to the physical state of the accelerator, and the liquid alkali-free accelerator can be further divided into a basic accelerator, a low-alkali accelerator and an alkali-free accelerator according to the alkalinity of the accelerator. The liquid alkali-free accelerator is a concrete accelerator which is liquid at normal temperature and normal pressure and has the pH value less than or equal to 7. The liquid alkali-free accelerator is mainly used as an additive of concrete in general, can remarkably improve the setting speed of the concrete, reduce the early strength of the concrete during setting, increase the hourly strength increasing rate, and has the advantages of low rebound and no strength loss after the concrete uses the liquid alkali-free accelerator.

The liquid alkali-free accelerator comprises the following components: fluoride, organic amine, silica sol, sulphoaluminate, amide and water; wherein the fluoride is AlF₃Wherein the fluoride is AlF₃。

Liquid alkali-free accelerator as described herein vs. solvent H₂O has no special requirement, common qualified tap water can be directly adopted in the actual use, the performance of the finished product of the liquid alkali-free accelerator can be met by adopting the common qualified tap water, and the production cost and the raw material acquisition difficulty of the liquid alkali-free accelerator can be obviously reduced by using the tap water. Specifically, the organic amine is (HOCH)₂CH₂)₂NH and/or (HOCH)₂CH₂)₃N, the sulphoaluminate is Al₂(SO₄)₃The amide is polyacrylamide, the molecular weight of the polyacrylamide is 150-250 ten thousand, and polyacrylamide with the molecular weight of 200 ten thousand is preferably adopted. The fluoride, the organic amine, the sulphoaluminate and the amide all adopt common commodities on the market.

Specifically, the liquid alkali-free accelerator comprises the following substances in percentage by mass:

the invention also provides a preparation method of the liquid alkali-free accelerator, which comprises the following steps:

1) adding H2O into the reaction container, adding fluoride while stirring, and reacting for 25-35 min;

2) adding organic amine and silica sol, and reacting for 35-45 min;

3) adding amide, and stirring for 15-25 min;

4) adding sulphoaluminate and reacting for 4-5 h.

And 4) observing whether the product is clear and transparent without precipitates after the step 4), if so, obtaining a finished product of the liquid alkali-free accelerator, and if not, continuing to react for 30min to obtain the finished product of the liquid alkali-free accelerator.