阅读说明：本技术 一种液体无碱速凝剂 (Liquid alkali-free accelerator ) 是由 刘辉 张彪 郑小芳 于 2020-04-30 设计创作，主要内容包括：一种液体无碱速凝剂,属于混凝土添加剂领域。由以下质量百分比组成的原料混合均匀得到液体无碱速凝剂：硫酸铝40％-50％、硫酸镁10％-15％、3-羟基-3-羧基戊二酸0.5％-1.5％、N,N-二乙基乙醇胺3％-8％、乙二胺四乙酸二钠1％-3％、二乙醇单异丙醇胺0.1％-0.3％、硫代硫酸钠0.5％-2％,其余为水。用于喷射混凝土,掺量一般为水泥质量的6％-8％,速凝效果好,并具有优异的早期和后期强度,同时速凝剂具有长期稳定性。(A liquid alkali-free accelerator belongs to the field of concrete additives. The liquid alkali-free accelerator is prepared by uniformly mixing the following raw materials in percentage by mass: 40 to 50 percent of aluminum sulfate, 10 to 15 percent of magnesium sulfate, 0.5 to 1.5 percent of 3-hydroxy-3-carboxyl glutaric acid, 3 to 8 percent of N, N-diethylethanolamine, 1 to 3 percent of disodium ethylene diamine tetraacetate, 0.1 to 0.3 percent of diethanol monoisopropanolamine, 0.5 to 2 percent of sodium thiosulfate and the balance of water. The quick-setting admixture is used for sprayed concrete, the mixing amount is generally 6% -8% of the mass of cement, the quick-setting effect is good, the early and later strength is excellent, and meanwhile, the quick-setting admixture has long-term stability.)

1. the liquid alkali-free accelerator is characterized in that the liquid alkali-free accelerator is obtained by uniformly mixing the following raw materials in percentage by mass: 40 to 50 percent of aluminum sulfate, 10 to 15 percent of magnesium sulfate, 0.5 to 1.5 percent of 3-hydroxy-3-carboxyl glutaric acid, 3 to 8 percent of N, N-diethylethanolamine, 1 to 3 percent of disodium ethylene diamine tetraacetate, 0.1 to 0.3 percent of diethanol monoisopropanolamine, 0.5 to 2 percent of sodium thiosulfate and the balance of water.

2. The liquid alkali-free accelerator as claimed in claim 1, wherein the accelerator comprises 45% to 50% of aluminum sulfate, 12% to 15% of magnesium sulfate, 0.6% to 0.8% of 3-hydroxy-3-carboxyglutaric acid, 5% to 7% of N, N-diethylethanolamine, 1% to 2% of disodium ethylenediamine tetraacetate, 0.1% to 0.3% of diethanol monoisopropanolamine, 0.5% to 2% of sodium thiosulfate and the balance of water.

3. The liquid alkali-free accelerator as claimed in claim 1, wherein the aluminum sulfate is Al₂O₃The quality content indicates the purity, and Al is selected₂O₃18-19% by mass of aluminum sulfate;

magnesium sulfate with the purity of 95-100% is selected as the magnesium sulfate;

the purity of N, N-diethylethanolamine is 85% -90%;

the purity of the diethanol monoisopropanolamine is 85 to 99 percent;

the purity of the sodium thiosulfate is 99-100 percent;

the purity of the disodium ethylene diamine tetraacetate is 99-100%.

4. The method for preparing a liquid alkali-free accelerator according to any one of claims 1 to 3, wherein after adding aluminum sulfate to water, magnesium sulfate, 3-hydroxy-3-carboxyglutaric acid, N-diethylethanolamine, disodium ethylenediaminetetraacetate are sequentially added, the mixture is stirred and heated by a mechanical stirring device until the mixture becomes a clear solution, and then diethanolisopropanolamine and sodium thiosulfate are sequentially added, the mixture is uniformly stirred, and the mixture is cooled to room temperature;

heating at 55-60 deg.C.

5. The use of the liquid alkali-free accelerator as set forth in any one of claims 1 to 3 for shotcrete, incorporated in an amount of 6% to 8% by mass of cement.

Technical Field

The invention belongs to the field of concrete additives, and particularly relates to an accelerator for building concrete.

Background

The concrete accelerator is an additive capable of quickly setting and hardening concrete, after the concrete accelerator is doped into the concrete, the concrete can be initially set within 2-5 min and finally set within 5-10 min, and the quick-setting early-strength action mechanism of the accelerator is that gypsum in the cement is changed into sodium sulfate and loses the retarding action, so that C is promoted₃A (tricalcium aluminate) hydrates rapidly and precipitates its hydration product crystals in solution, causing the cement slurry to set rapidly. The commonly used accelerating agents are alkali accelerating agents and alkali-free accelerating agents, the alkali accelerating agents have strong alkalinity and can cause physical injury to first-line constructors, the alkali-free accelerating agents are less in application at present, and the alkali-free accelerating agents are alkali-free accelerating agents prepared by taking hydrofluoric acid as a raw material and alkali-free accelerating agents not prepared by hydrofluoric acidThe production conditions of the alkali-free accelerator prepared by taking hydrofluoric acid as a raw material are harsh, the hydrofluoric acid with strong toxicity and corrosivity can be used, hydrofluoric acid residues and a small amount of other fluorides can still be generated after the product is produced, and the risk of health damage can be brought to constructors. The existing alkali-free accelerator prepared from hydrofluoric acid has the strength of 5-7MPa in 1 day and the strength retention rate of 100-120% in 28 days; the alkali-free accelerator not prepared from hydrofluoric acid has better environmental protection property, the strength of 1 day is usually 10-14MPa, but the strength of 28 days is reduced, and the retention rate is usually 80-90%. The supersaturated aluminum sulfate in the existing liquid alkali-free setting accelerator can generate a plurality of aluminum hydroxyl multi-nuclear complex ions through hydrolysis reaction of aluminum ions, and finally generate aluminum hydroxide precipitate, and although a stabilizing agent is added into the existing liquid alkali-free setting accelerator, the stabilization period is limited.

Disclosure of Invention

The invention aims to provide a method for preparing a liquid alkali-free setting accelerator without hydrofluoric acid, which can improve the strength of 1 day and the strength of 28 days at the same time.

It is another object of the present invention to provide a liquid alkali-free quick-setting admixture obtained by the preparation method.

The invention provides a liquid alkali-free accelerator which is prepared by uniformly mixing the following raw materials in percentage by mass: 40 to 50 percent of aluminum sulfate, 10 to 15 percent of magnesium sulfate, 0.5 to 1.5 percent of 3-hydroxy-3-carboxyl glutaric acid, 3 to 8 percent of N, N-diethylethanolamine, 1 to 3 percent of disodium ethylene diamine tetraacetate, 0.1 to 0.3 percent of diethanol monoisopropanolamine, 0.5 to 2 percent of sodium thiosulfate and the balance of water.

Preferably 45 to 50 percent of aluminum sulfate, 12 to 15 percent of magnesium sulfate, 0.6 to 0.8 percent of 3-hydroxy-3-carboxyl glutaric acid, 5 to 7 percent of N, N-diethylethanolamine, 1 to 2 percent of disodium ethylene diamine tetraacetate, 0.1 to 0.3 percent of diethanol monoisopropanolamine, 0.5 to 2 percent of sodium thiosulfate and the balance of water.

The aluminum sulfate can be selected from commercially available industrial grade hydrated aluminum sulfate, which is generally used with Al₂O₃The purity is characterized by mass content, and Al is preferably selected₂O₃18 to 19 mass percent of aluminum sulfate.

The magnesium sulfate can be selected from commercially available industrial grade hydrated magnesium sulfate, and its MgSO is generally used₄The quality content is characterized by its purity, preferably MgSO₄95-100% of aluminum sulfate.

The 3-hydroxy-3-carboxyl glutaric acid can be directly selected from commercially available industrial products, and the mass content is 85-99%.

The N, N-diethylethanolamine can be directly selected from commercially available industrial grade N, N-diethylethanolamine, the purity of the N, N-diethylethanolamine is generally characterized by the mass content of the N, N-diethylethanolamine, and the mass content of 85-90% is preferably selected.

The diethanol monoisopropanolamine can be directly selected from commercially available industrial diethanol monoisopropanolamine, the purity of the diethanol monoisopropanolamine is generally characterized by the mass content of the diethanol monoisopropanolamine, and the diethanol monoisopropanolamine is preferably selected to be 85-99% by mass.

Sodium thiosulfate can be selected from commercially available industrial sodium thiosulfate, and Na is used as common sodium thiosulfate₂S₂O₃The purity is characterized by mass content, and Na is preferably selected₂S₂O₃The mass content is 99-100%.

Disodium edetate is a commercially available technical grade product, commonly used as C₁₀H₁₄N₂Na₂O₈The purity of the product is characterized by mass content, and the C10H14N2Na2O8 mass content is preferably 99-100%.

Specifically, in order to promote dissolution and uniform mixing, the preparation method comprises the steps of adding aluminum sulfate into water, then sequentially adding magnesium sulfate, 3-hydroxy-3-carboxyl glutaric acid, N-diethylethanolamine and disodium ethylene diamine tetraacetate, stirring and heating the mixture by using a mechanical stirring device until the mixture turns into a clear solution, then sequentially adding diethanol monoisopropanolamine and sodium thiosulfate, uniformly stirring, and cooling to room temperature.

The heating temperature should be suitable for the aqueous system and at the same time facilitate the final clear solution, and the optimum heating temperature can be determined experimentally by the skilled person, and is typically 55-60 ℃.

Compared with the prior art, the invention mainly has the following characteristics:

the diethanol monoisopropanolamine and the sodium thiosulfate are added, and the diethanol monoisopropanolamine is easily adsorbed on the surfaces of calcium aluminoferrite, tricalcium silicate and dicalcium silicate in a form of coordinate bonds, so that the solubility of three insoluble minerals in a liquid phase is effectively promoted, the hydration degree of cement minerals is promoted, the early and later strength of mortar can be enhanced, and particularly the later strength of cement is enhanced; the sodium thiosulfate can obviously improve the generation rate of C-S-H gel, calcium hydroxide and ettringite in the process of cement hydration for 1 day, and further supplements and enhances the early strength of the cement on the basis of the diethanol monoisopropanolamine.

The disodium ethylene diamine tetraacetate can form a complex with high solubility with aluminum ions by adding the disodium ethylene diamine tetraacetate, and has long-term stability.

In a second aspect of the present invention, there is provided a liquid alkali-free quick-setting admixture obtained by the above-mentioned production method. The liquid alkali-free accelerator is used for sprayed concrete, the mixing amount is generally 6% -8% of the mass of cement, the accelerating effect is good, and the liquid alkali-free accelerator has excellent early and later strength.

Detailed Description

The present invention will be further described with reference to the following examples.

The test methods and equipment models in the following examples are as follows:

the test method is as follows:

the test of the liquid alkali-free accelerator for sprayed concrete is carried out according to the test method of JC477-2005 accelerator for sprayed concrete.

The equipment comprises the following parts:

the equipment involved in the test procedure was as follows: the digital display electric stirrer produced by Changzhou Ronghua apparatus manufacturing Limited company, the balance produced by Tianjin Tianma balance base apparatus Limited company, the HH-1 digital display constant temperature water bath of Changzhou city Jiannan laboratory instrument plant, the NJ-160A type cement paste mixer produced by Wuxi Jian apparatus machinery Limited company, the JJ-5 type cement glue sand mixer produced by Wuxi Jian apparatus machinery Limited company, the ZS-15 type cement glue sand jolt produced by Beijing Rou engineering and technology Limited company, the Vicat apparatus produced by Wuxi Huanan apparatus Limited company, the KZJ-500 type electric bending tester produced by Shenyang Changcheng electromechanical equipment plant, and the HYE-300 full-automatic constant stress pressure tester produced by Beijing Ronghuawang construction machinery Limited company.