Low-resilience alkali-free liquid accelerator for concrete and preparation method thereof

文档序号：644453 发布日期：2021-05-14 浏览：23次中文

阅读说明：本技术 一种混凝土低回弹无碱液体速凝剂及制备方法 (Low-resilience alkali-free liquid accelerator for concrete and preparation method thereof ) 是由倪锐胡凯伟刘子毅于浩沈学涛于 2019-11-14 设计创作，主要内容包括：本发明涉及一种混凝土低回弹无碱液体速凝剂,属于混凝土外加剂应用领域。所述低回弹无碱液体速凝剂为水分散溶液,由如下质量百分含量的组分制备而成：改性明矾27％～45％、分散剂5％～10％、絮凝剂2％～6％、乳化剂0.4％～1.0％、纳米纤维0.1％～0.5％、水45％～65％。本发明低回弹无碱液体速凝剂能够有效的降低喷射回弹量,并提高喷射混凝土早期硬化强度,本发明环保无碱、无氯离子、工艺简单、性能稳定。(The invention relates to a low-resilience alkali-free liquid accelerator for concrete, belonging to the field of application of concrete admixtures. The low-resilience alkali-free liquid accelerator is an aqueous dispersion solution and is prepared from the following components in percentage by mass: 27-45% of modified alum, 5-10% of dispersant, 2-6% of flocculant, 0.4-1.0% of emulsifier, 0.1-0.5% of nano-fiber and 45-65% of water. The low-resilience alkali-free liquid accelerator can effectively reduce the spraying resilience amount and improve the early hardening strength of sprayed concrete, and is environment-friendly, alkali-free, chloride-ion-free, simple in process and stable in performance.)

1. The concrete low-resilience alkali-free liquid accelerator is characterized by comprising the following raw material components in percentage by mass:

2. the concrete low-resilience alkali-free liquid accelerator as claimed in claim 1, wherein the modified alum is obtained by dissolving alum and hydrated magnesium silicate in water, then dropwise adding nano-alumina sol, and performing modification at 50-70 ℃ for 1-2 h; wherein the alum, the nano alumina sol, the hydrated magnesium silicate and the water are prepared according to the following mass ratio: 18 to 25 percent of alum; 12 to 18 percent of nano aluminum sol; 0.5 to 1 percent of hydrated magnesium silicate; 58 to 64 percent of water.

3. The low-resilience alkali-free liquid accelerator for concrete as claimed in claim 1, wherein the dispersant is triethyl phosphate, dimethyl phosphite or 2-ethylhexyl diphenyl phosphate.

4. The concrete low-resilience alkali-free liquid accelerator according to claim 1, wherein the flocculant is polyferric sulfate or polyferric silicate sulfate.

5. The concrete low-resilience alkali-free liquid accelerator as claimed in claim 1, wherein the emulsifier is polyoxyethylene octylphenol ether, polyoxyethylene nonylphenol ether or polyoxyethylene castor oil ether.

6. The concrete low-resilience alkali-free liquid accelerator according to claim 1, wherein the diameter of the nano-fiber is 80nm to 100 nm.

7. A method for preparing the concrete low-resilience alkali-free liquid accelerator as defined in claim 1, which comprises the following steps: weighing the raw materials according to the mass percentage of the raw material components, putting the weighed raw materials into a reaction kettle, and putting the reaction kettle into a water bath kettle at the temperature of 50-60 ℃ to be uniformly stirred, thus obtaining the concrete low-resilience alkali-free liquid accelerator.

Technical Field

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

Background

Since the popularization of concrete wet-spraying construction technology in 90 s of the 20 th century, how to ensure the quality of a sprayed concrete finished product and smoothly spray the sprayed concrete is one of the key problems of engineering construction for high-performance sprayed concrete with high strength and high durability requirements in China. The liquid accelerator with excellent performance and good accelerating effect is a precondition for popularizing the wet spraying process in China. The liquid accelerator developed at present has the problems of poor stability, high alkali content, high injection viscosity, short stabilization period, 1d compressive strength of less than 6MPa, poor adaptability to cement and the like. Furthermore, the duration of winter is long in northern China and Qinghai-Tibet plateau areas, and along with the development of engineering construction, the long cold temperature brings many problems to the winter construction of concrete. Generally, the freezing point is lowered by adding industrial salt into concrete, so that liquid water required for hydration of cement in concrete at a certain negative temperature can be ensured. However, when the liquid accelerator meets a negative temperature environment or a low temperature environment, the viscosity of the liquid accelerator is increased, the liquid accelerator is not beneficial to jet pump suction, the mixing amount is seriously affected, the rebound rate is increased, and the initial hardening strength is reduced.

The patent (US2002035952A1) discloses a preparation method of an alkali-free liquid accelerator, which comprises the steps of dissolving aluminum sulfate and aluminum hydroxide by using 40% hydrofluoric acid, and adding 4.5-7.5% organic amine, wherein the content of the aluminum sulfate is 20-40%, and the content of the aluminum hydroxide is 10%. Hydrofluoric acid is a high-risk chemical raw material, has strong corrosivity to human bodies, and is not beneficial to production and use. Most current accelerators contain organic alcohol amine components and organic alcohol amine chemicals for modifying the accelerator. The main reasons for the coagulation acceleration effect of the organic alcohol amine on the cement are to accelerate the hydration of C3A, accelerate the formation of ettringite and C-S-H gel with high CaO/SiO2 ratio, accelerate the formation of diaspore and rapidly convert the diaspore into a cubic crystal form; meanwhile, due to the formation of soluble complex, the concentration of Ca2+ and Al3+ in the cement paste is reduced, so that the reaction of other cement minerals is promoted, but the viscosity of the accelerator system is easily increased along with the reduction of the temperature of the organic alcohol amine, and the accelerator is more unfavorable for use in winter under negative temperature or low temperature environment.

Disclosure of Invention

The invention aims to disclose a concrete low-resilience alkali-free liquid accelerator, which overcomes the technical defects of the existing accelerator used for spraying concrete and can effectively improve the phenomenon that the stress deadweight generated by the alkali-free accelerator during spraying seriously falls off blocks; the invention also aims to provide a preparation method of the concrete low-resilience alkali-free liquid accelerator.

The technical scheme of the invention is as follows: the concrete low-resilience alkali-free liquid accelerator is characterized by comprising the following raw material components in percentage by mass:

preferably, the modified alum is obtained by dissolving alum and hydrated magnesium silicate in water, then dropwise adding nano aluminum sol, and performing modification for 1-2 h at 50-70 ℃ after dropwise adding reaction; wherein the alum, the nano alumina sol, the hydrated magnesium silicate and the water are prepared according to the following mass ratio: 18 to 25 percent of alum; 12 to 18 percent of nano aluminum sol; 0.5 to 1 percent of hydrated magnesium silicate; 58 to 64 percent of water.

Preferably, the dispersant is triethyl phosphate, dimethyl phosphite or 2-ethylhexyl diphenyl phosphate.

Preferably, the flocculating agent is polymeric ferric sulfate or polymeric ferric silicate sulfate.

Preferably, the emulsifier is octyl phenol polyoxyethylene ether, nonyl phenol polyoxyethylene ether or castor oil polyoxyethylene ether.

Preferably, the nanofiber has a diameter of 80nm to 100 nm.

The invention also provides a method for preparing the concrete low-resilience alkali-free liquid accelerator, which comprises the following steps: weighing the raw materials according to the mass percentage of the raw material components, putting the weighed raw materials into a reaction kettle, and putting the reaction kettle into a water bath kettle at the temperature of 50-60 ℃ to be uniformly stirred, thus obtaining the concrete low-resilience alkali-free liquid accelerator.

According to the invention, the surface structure of the alum is treated by modifying the alum, so that the hydrolyzed aluminum hydroxide has better adsorption performance, and the alkali-free liquid accelerator system has better anchoring effect by secondary modification of the dispersant, the flocculant and the emulsifier, so that the rebound rate of concrete is effectively reduced. The invention has no alkali, chlorine and corrosion, obviously improves the construction capability of the tunnel shotcrete, and reduces the cost waste caused by large rebound quantity. The invention has the advantages of no layering phenomenon, simple preparation process, environment-friendly and pollution-free raw materials, and suitability for large-scale popularization and use.

Detailed Description

Example 1

The preparation method of the concrete low-resilience alkali-free liquid accelerator comprises the following steps:

step 1: dissolving 180g of alum and 10g of hydrated magnesium silicate in 630g of water, then dropwise adding 180g of nano-alumina sol, and carrying out dropwise reaction for 1h at 50 ℃ to obtain modified alum;

step 2: