阅读说明：本技术 一种高耐久性液体无碱速凝剂及其制备方法 (High-durability liquid alkali-free accelerator and preparation method thereof ) 是由 刘俊元 李晓帆 彭静 孔韬 赵宇翔 王靖 查炎鹏 于 2019-11-08 设计创作，主要内容包括：本发明公开了一种喷射混凝土用高耐久性液体无碱速凝剂及其制备方法,以质量份数计,其原料包括：硫酸铝400～600份、有机醇胺10～50份、高吸水树脂5～20份、早强组份10～100、稳定剂5～20份、水300～500份。该产品能满足最新的速凝剂国家标准,具有碱含量低,一天抗压强度高,28天抗压轻度比大于100%,且90天抗压强度不倒缩等优点。其中的高吸水树脂在液体速凝剂中起到了增稠稳定作用,和混凝土混合初期物理吸水作用能加快混凝土凝结,降低回弹,水化过程中可以慢慢释放水分,对混凝土起到了内养护的作用,在服役期能起到防水堵漏自修复的作用,因此极大提高了混凝土的耐久性能,且生产过程中没有使用氢氟酸等有毒有害成分,不用加热,符合绿色环保的建筑材料。(The invention discloses a high-durability liquid alkali-free accelerator for sprayed concrete and a preparation method thereof, wherein the high-durability liquid alkali-free accelerator comprises the following raw materials in parts by mass: 400-600 parts of aluminum sulfate, 10-50 parts of organic alcohol amine, 5-20 parts of super absorbent resin, 10-100 parts of early strength component, 5-20 parts of stabilizer and 300-500 parts of water. The product can meet the latest national standards of the accelerator, and has the advantages of low alkali content, high compressive strength in one day, compression strength ratio of more than 100% in 28 days, no collapse of compressive strength in 90 days and the like. The super absorbent resin plays a role in thickening and stabilizing in the liquid accelerator, concrete condensation can be accelerated by the physical water absorption effect at the initial stage of mixing with the concrete, resilience is reduced, moisture can be slowly released in the hydration process, the effect of internal curing is played on the concrete, the effect of waterproof plugging and self-repairing can be played in the service period, the durability of the concrete is greatly improved, toxic and harmful components such as hydrofluoric acid are not used in the production process, heating is not needed, and the building material is green and environment-friendly.)

1. A high-durability liquid alkali-free accelerator for sprayed concrete comprises the following raw materials in parts by mass: 400-600 parts of aluminum sulfate, 10-50 parts of organic alcohol amine, 5-20 parts of super absorbent resin, 10-100 parts of early strength component, 5-20 parts of stabilizer and 300-500 parts of water; the product can meet the latest national standards of the accelerator, and has the advantages of low alkali content, high compressive strength in one day, compression strength ratio of more than 100% in 28 days, no collapse of compressive strength in 90 days and the like; and toxic and harmful components such as hydrofluoric acid and the like are not heated in the production process, so that the environment-friendly building material is met.

2. The liquid alkali-free accelerator according to claim 1, wherein the aluminum sulfate is 18-water aluminum sulfate, Al, which is iron-free or low-iron₂O₃The content is more than or equal to 15.6 percent, and the content of iron is less than 0.5 percent.

3. The liquid alkali-free accelerator according to claim 1, wherein the organic alcohol amine is one or more of triethanolamine, diethanolamine and N-methyldiethanolamine.

4. The alkali-free liquid setting accelerator according to claim 1, wherein the super absorbent resin is a polyacrylic acid series super absorbent resin, and has the advantages of low cost, high water absorption capacity, long product shelf life and the like.

5. The liquid alkali-free accelerator according to claim 1, wherein the early strength agent is one or a combination of ethylene glycol, glycerol and diethylene glycol.

6. A method for producing an alkali-free accelerator as set forth in any one of claims 1 to 5, characterized by comprising the steps of:

step (1): putting the water with the proportion into a reaction kettle, adding aluminum sulfate while stirring, and stirring until the aluminum sulfate is completely dissolved;

step (2): putting the super absorbent resin into the reaction kettle in the step (1) and continuously stirring uniformly until the super absorbent resin is completely dissolved to form uniform liquid;

and (3): and (3) adding the early strength component and the organic alcohol amine into the reaction kettle in the step (2) and continuously stirring for 30-50 minutes to obtain a finished product.

Technical Field

The invention relates to the technical field of concrete admixtures for civil engineering, in particular to a high-durability liquid alkali-free accelerator and a preparation method thereof.

Background

The liquid accelerator is an additive indispensable in a wet spraying process. At present, the more used liquid setting accelerators are aluminate alkaline setting accelerators, and the alkali content of the liquid setting accelerators is between 10 and 20 percent. The alkaline accelerator has strong stimulation and corrosion effects on eyes, skin and respiratory system of constructors, and can cause injury to the constructors who are engaged in spray construction for a long time despite of adopting necessary labor protection measures during operation. In addition, the alkaline accelerator greatly increases the possibility of alkali aggregate reaction of the sprayed concrete, and the later strength of the sprayed concrete is inversely contracted by up to 20-40%. The alkali-free liquid accelerator is used as an important building material, improves the later strength of sprayed concrete, is one of key ways for improving the durability of the sprayed concrete, and has a significant promoting effect on the construction of important projects such as urban underground traffic, hydraulic engineering, high-speed rail tunnels, underground powerhouses and the like.

The super absorbent resin is more and more widely applied to concrete as an internal curing material. The super absorbent resin is used in the liquid alkali-free accelerator, plays a role of a thickening stabilizer in a liquid state, prevents the layered precipitation of products, absorbs a part of stirring water after the accelerator and concrete are mixed and sprayed to a working surface, can shorten the setting time of the concrete, reduces the rebound rate of the sprayed concrete, reduces the internal relative humidity of the concrete along with the progress of cement hydration, starts to release water, promotes the hydration of the cement, improves the strength of the concrete due to the increase of hydration products, is favorable for improving the anti-shrinkage performance of the concrete, and greatly improves the durability of the concrete.

According to the research on domestic and foreign documents, CN 108395159A invents that the super absorbent resin and the expanded vermiculite are used for preparing the shotcrete, and the super absorbent resin is not used in the liquid alkali-free setting accelerator.

The current accelerator industry at home and abroad develops very rapidly, and although the occupation rate of the alkaline accelerator in the market is high, the occupation rate of the alkali-free accelerator in the market is gradually increased. Therefore, research and development of a set of production and process of the high-efficiency alkali-free or low-alkali liquid accelerator suitable for the current situations of various cement varieties and complicated sprayed concrete construction environments in China are of great significance for solving the key problems in sprayed concrete construction and meeting the requirements of sprayed concrete construction in engineering.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a liquid alkali-free accelerator which has the advantages of low alkali content, short setting time, high compressive strength in one day, high compressive strength ratio in 28 days, good later strength, greatly improved concrete durability, no harmful components such as chloride ions and the like, no toxic and harmful components such as hydrofluoric acid and the like in the production process, and is a building material meeting the requirements of environmental protection.

In order to achieve the purpose, the invention provides the following technical scheme: a liquid alkali-free accelerator for sprayed concrete comprises the following raw materials in parts by weight: 400-600 parts of aluminum sulfate, 10-50 parts of organic alcohol amine, 5-20 parts of super absorbent resin, 10-100 parts of early strength component, 5-20 parts of stabilizer and 300-500 parts of water.

More preferably, the aluminum sulfate is 18-element aluminum sulfate without iron or with low iron, the content of Al2O3 is more than or equal to 15.6 percent, and the content of iron is less than 0.5 percent.

In the invention, the organic alcohol amine is preferably one or a combination of more of triethanolamine, diethanolamine and azomethyldiethanolamine.

The super absorbent resin is preferably polyacrylic acid series super absorbent resin, and has the advantages of low cost, strong water absorption capacity, long product quality guarantee period and the like.

In the invention, the stabilizer is preferably one or a combination of oxalic acid, phosphoric acid and sulfosalicylic acid.

In the invention, the early strength agent is preferably one or a combination of more of magnesium sulfate heptahydrate, ferrous sulfate heptahydrate, ethylene glycol, glycerol and diethylene glycol.

The invention also aims to provide a preparation method of the liquid alkali-free accelerator.

In order to achieve the purpose, the invention provides the following technical scheme: a preparation method of the liquid alkali-free accelerator comprises the following steps:

step (1): putting the water with the proportion into a reaction kettle, starting stirring, adding the stabilizer, then adding the aluminum sulfate while stirring, and stirring until the aluminum sulfate is completely dissolved;

step (2): putting the super absorbent resin into the reaction kettle in the step (1) and continuously stirring uniformly until the super absorbent resin is completely dispersed to form uniform liquid;

and (3): and (3) adding the early strength component and the organic alcohol amine into the reaction kettle in the step (2) and continuously stirring for 30-50 minutes to obtain a finished product.

Compared with the prior art, the invention has the following beneficial effects:

(1) the super absorbent resin is used in the liquid alkali-free accelerator, plays a role in thickening and stabilizing when in a liquid state, can prevent a product from layering and precipitating, and can absorb a part of stirring water after the accelerator and concrete are mixed and sprayed on a working surface, so that the setting time of the concrete can be shortened, the rebound of the sprayed concrete is reduced, the relative humidity in the concrete is reduced along with the progress of cement hydration, the super absorbent resin starts to release water, the cement hydration is promoted, the increase of hydration products not only improves the strength of the concrete, but also is beneficial to improving the anti-shrinkage performance of the concrete, and the durability of the concrete is greatly improved; (2) the liquid alkali-free accelerator disclosed by the invention has the advantages of low mixing amount, short condensation time, high compressive strength in one day, high compressive strength ratio in 28 days, no strength collapse in 90 days, no chlorine and alkali, no toxic and harmful components such as hydrofluoric acid and the like in the production process, and is a building material which is in line with green and environment-friendly properties.

Detailed Description

The present embodiment is only for explaining the present invention, and it is not limited to the present invention, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present invention.

All materials referred to in the examples of the present invention are commercially available.

Table 1 examples 1-6 product formulations (g/Kg).

The results of the homogeneity test of the trial-made alkali-free accelerator are shown in the following table.

Table 2 results of the homogeneity test of the products of examples 1 to 6.

The properties of the slurries and mortars using different cement doped accelerators are shown in the table below.

TABLE 3 neat and mortar properties of the admixtures of accelerators (reference cement P. I. 42.5 Portland cement).

Table 4 neat paste and mortar properties of admixture accelerators (cube corner p.o.42.5 portland cement).

TABLE 5 Net and mortar properties of the admixture accelerator (Pu-Er-Tianheng P.O.42.5 Portland cement).

In conclusion, the high-durability liquid alkali-free accelerator disclosed by the invention uses the super absorbent resin to play a thickening and stabilizing role in the liquid accelerator, the physical water absorption effect in the initial stage of mixing with concrete can accelerate the concrete condensation and reduce the resilience, the water can be slowly released in the hydration process, the internal curing effect on the concrete is played, and the waterproof, leak-stopping and self-repairing effects can be played in the service period, so that the durability of the concrete is greatly improved, toxic and harmful components such as hydrofluoric acid are not used in the production process, the heating is not needed, and the high-durability liquid alkali-free accelerator is a building material which is in line with the green and environment protection. And the alkali-free accelerator completely meets the requirements of a liquid alkali-free accelerator in GB/T35159-2017 accelerator for sprayed concrete, has good adaptability to different cements, and is worthy of great popularization.