Composite modified nano aluminum sol, preparation method thereof and application of composite modified nano aluminum sol in sulfur-free alkali-free accelerator

Abstract

The invention discloses composite modified nano aluminum sol, a preparation method thereof and application of the composite modified nano aluminum sol in a sulfur-free alkali-free accelerator. The composite modified nano aluminum sol material disclosed by the invention is prepared from nano aluminum sol loaded by carrier particles with an interlayer structure and a cement hydration reaction activity modifier. The stability and the coagulation accelerating effect are better; the prepared sol modified sulfur-free alkali-free accelerator has the green and environment-friendly characteristics of being free of fluorine, sulfur and corrosion, the hour strength of the accelerator develops rapidly, the strength of mortar in 6 hours is larger than 3.0 MPa, and the strength of mortar in 24 hours is 18.0 MPa or above. According to common sprayed concrete adopting the sol modified sulfur-free alkali-free accelerator, by effectively reducing the content of sulfate radicals in the liquid alkali-free accelerator, the sulfate corrosion degradation resistance of a sprayed concrete material is remarkably improved, and the sulfate corrosion resistance grade is KS120 or above.

Description

technical field [0001] The invention belongs to the technical field of concrete admixtures, and particularly relates to a composite modified nano-aluminum sol, a preparation method thereof, and its application in a sulfur-free and alkali-free setting accelerator. Background technique [0002] Liquid accelerator is an important admixture for wet shotcrete. Its function is mainly to shorten the setting and hardening time of concrete, improve the bonding effect between concrete and the sprayed surface, and achieve the purpose of controlling the rebound rate of spraying and stabilizing the weak surrounding rock. [0003] The early liquid accelerator products revolved around alkali-containing systems such as sodium aluminate or sodium silicate sodium silicate, which often contained relatively high alkali content. 2 O equivalent, mostly at the content level of 10-20%. With the decrease of concrete strength in the later stage, the high risk of alkali-aggregate reaction and the cor...

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Problems solved by technology

[0006] The second problem is the use of high-content fluorine-containing acid or fluorine salt: In recent years, there have been many development ideas for using fluorine-containing acid or fluorine salt to improve the coagulation performance of liquid alkali-free accelerators. Due to the insufficient solubility of aluminum sulfate, some patents Most of them use hydrofluoric acid, fluosilicic acid or other fluorine-containing acid to react with aluminum hydroxide to enhance the concentration of aluminum phase in the alkali-free accelerator, but when the proportion of fluoride-containing acid or fluorine salt is high, it is easy to cause pH of the accelerator system. Low, the early strength of concrete is low (Zeng Luping, The influence of alkali-free accelerator on the early hydration of Portland cement, 2019), followed by the risk of corrosion in production and use, and fluoride is easy to contact or ingest into the human body Health hazards such as fluorosis

[0007] The third problem is the slow development of early strength: the weak surrounding rock needs sprayed concrete to quickly form a certain hour strength to achieve the stability of the surrounding rock, and the addition of the alkali-free accelerator of the aluminum sulfate system is likely to cause the rapid formation of early ettringite , and then wrap the cement particles at the early stage of hydration, inhibit the formation of early hydration products and slow down the early strength of shotcrete

Chinese patent CN111333362A discloses a low-volume, high-early-strength non-alkali liquid quick-setting agent, which uses lithium nitrate and calcium silicate hydrate to improve the early strength of the non-alkali quick-setting agent, but still adopts the design of high aluminum sulfate , its ratio is more than 50%, and secondly mixed with a certain amount of fluoroaluminum complex solution, it is easy to cause the instability of calcium silicate hydrate gel structure (Research paper, Aliona Iljina, The stability of formed CaF 2 and its influence on the thermal behavior of C–S–H in CaO–silica gel waste-H 2 O system, 2017)

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