Anti-freezing alkali-free liquid accelerator and preparation method thereof

Abstract

An anti-freezing alkali-free liquid accelerator and a preparation method thereof are disclosed. The accelerator is mainly prepared from water-soluble aluminium salt, polyaluminium salt, alkaline earthnitrate and / or carbonate, alkaline earth fluoride salt, alcamines organic matter and water. The preparation method comprises the following steps: firstly dissolving a part of water-soluble aluminiumsalt by the use of a part of water, heating and stirring, adding polyaluminium salt and alkaline earth nitrate and / or carbonate, heating and reacting, cooling, successively adding alkaline earth fluoride salt, alcamines organic matter and the rest of water-soluble aluminium salt, adding the rest of water, and filtering. After the accelerator with the dosage of 4% is added into cement, initial setting time of cement paste is less than or equal to 4 min, and final setting time is less than or equal to 8 min; and early strength and long-term strength are both high. The accelerator of the invention has good storage stability at room temperature, low temperature and high temperature. In the case of redissolving after freezing, almost no precipitate is precipitated out, and the rapid hardening effect is not attenuated. The method of the invention has advantages of simple process, low cost and zero emission, and is suitable for industrial production.

Description

technical field [0001] The invention relates to an accelerator and a preparation method thereof, in particular to an anti-freezing type non-alkali liquid accelerator and a preparation method thereof. Background technique [0002] Concrete accelerator, also known as coagulant, is a chemical admixture that can promote the rapid setting and hardening of cement or concrete, and produce a certain strength in a short period of time. , As well as plugging and emergency repair projects have been widely used. Accelerator, as a chemical admixture product in the concrete industry, its production and use history can be traced back to the 1930s. The birth and use of accelerators made shotcrete construction possible, and played an important role in the establishment of shaft shotcrete support technology. [0003] The indicators to measure the quality of the accelerator mainly include physical and chemical properties such as storage stability and antifreeze of the accelerator; performanc...

AI Technical Summary

Problems solved by technology

[0005] There are many kinds of accelerators developed at home and abroad. The earlier accelerators are mainly composed of solids such as aluminates and carbonates. The most commonly used traditional accelerators in underground engineering construction at home and abroad are sodium silicate, aluminate, etc. Salt accelerators and alkaline earth metal carbonates are alkaline powder accelerators. Although they can meet the requirements for acceleration in construction, the strength loss of concrete in the later stage is large, and its 28-day strength retention rate is generally only 65%. %, one of the reasons recognized by the industry is that the introduction of a large amount of alkaline substances in traditional accelerators results in alkali-aggregate reaction

At the end of the 1970s, low-alkali and non-alkali liquid accelerators were studied and tried at home and abroad, but the overall performance was still difficult to meet the current actual market demand.

[0006] The traditional quick-setting agent has strong alkalinity. Although its dosage is low, the strength loss of concrete in the later period is relatively large, and it will cause great harm to the skin and respiratory tract of the builder, and the working environment is poor; followed by low-alkali and no-alkali Although liquid accelerators solve some of the problems of alkaline accelerators, such as dust and high alkalinity, they generally have poor storage stability, large additions, and higher production costs for stronger alkali accelerators. Defects, in addition, in order to reduce the dosage, the newly developed liquid accelerator must increase its solid content, which makes the accelerator easy to precipitate in low temperature environment, so its antifreeze performance is generally poor

[0007] US8118930B2 "Setting accelerator for sprayed concrete" discloses a non-alkali liquid quick-setting agent, although its quick-setting effect is better when the dosage is 5%, but the stability period of the accelerator can only meet 8 weeks, if it cannot be transported in time Use, it will become invalid, resulting in loss

[0008] US8246742B2 "Accelerator mixture and method of use" discloses a liquid alkali-free accelerator. Although it has good stability in the temperature range of 5-40°C, the amount of the accelerator is as high as 8-10 %, unable to meet the current demand that the amount of additives used on the construction site be controlled below 4%.

[0009] CN1974466A discloses a liquid alkali-free quick-setting agent for sprayed concrete. Although its quick-setting effect and cement adaptability are good, the addition amount of the quick-setting agent is as high as more than 10%, which cannot meet the requirements of the current construction site. Demand below 4%

[0010] CN102219425A discloses an alkali-free quick-setting agent and its preparation method. Aluminum sulfate, aluminum hydroxide, hydrofluoric acid, water glass and stabilizers are used. Although the dosage is 2-6%, the cement adaptability is good, but , due to its use of Na-containing + Ionic silicates are not strictly alkali-free accelerators

[0011] CN106431059A discloses a non-alkali liquid quick-setting agent for sprayed concrete and a preparation method thereof, using aluminum sulfate, magnesium fluoride, sodium fluoride, hydrofluoric acid, water glass, triethanolamine and polyacrylamide as raw materials, However, due to the use of part of the alkali metal sodium salt, it will cause a loss of strength in the later stage

[0012] CN105481280A discloses a non-alkali and chlorine-free liquid accelerator based on PASiC and / or PASSi. Although the process is simple and the cement adaptability is good, more inorganic acids phosphoric acid, sulfuric acid and hydrofluoric acid are used in the formula to Stabilize the polymer system, while there may be retarding side effects

[0013] To sum up, commercially available low-alkali and alkali-free liquid accelerators generally have problems such as high dosage, long setting time, low 28-day strength retention rate, and poor storage stability.

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