A liquid setting time adjustable accelerator for concrete and its preparation method

Abstract

This invention discloses a liquid accelerator for concrete with adjustable setting time and its preparation method. The liquid accelerator comprises the following raw materials by weight percentage: 40%-45% polyaluminum sulfate, 3%-5% phosphoric acid, 0.1%-0.5% reactive initial setting component, 2%-4% final setting component, 1%-2% water-soluble polyvinyl alcohol, and the remainder being water. The reactive initial setting component includes polyethylene glycol diglycidyl ether and dendritic polylysine; the final setting component includes diethanolamine monoisopropanolamine and carboxytetraethylene glycol monomethyl ether. The initial setting time and final setting time of the liquid accelerator of this invention can be controlled separately. Specifically, the initial setting time of the accelerator is controlled by controlling the content of polyethylene glycol diglycidyl ether and dendritic polylysine; the final setting time of the accelerator is controlled by controlling the content of diethanolamine monoisopropanolamine and carboxytetraethylene glycol monomethyl ether.

Description

Technical Field

[0001] This invention relates to the field of building material admixtures, specifically to a liquid quick-setting agent for concrete with adjustable setting time and its preparation method. Background Technology

[0002] Currently, the accelerated pace of large-scale mining, tunnel excavation, and the construction of highway and railway networks has led to a significant increase in the use of accelerators, placing higher demands on their performance and quality. At present, research on liquid accelerators in my country is still in its early stages, and many problems remain unsolved. The main issue is that the initial setting time and final setting time of existing liquid accelerators cannot be adjusted separately.

[0003] The initial and final setting times of existing liquid accelerators are usually consistent; that is, a long initial setting time corresponds to a long final setting time, and a short initial setting time corresponds to a short final setting time. This results in limited adaptability of existing liquid accelerators, which cannot be adjusted according to different construction types.

[0004] In terms of initial setting time, a short initial setting time means that the concrete begins to harden quickly and is not easily deformed by external wind in the early stages, making it suitable for simple structures such as retaining walls and tunnel linings; a long initial setting time means that the concrete hardens slowly and is suitable for complex structures that require a long time for concrete laying and leveling, such as irregular columns and densely reinforced beams.

[0005] In terms of final setting time, a short final setting time means that the concrete hardens completely in a short time, allowing for a quick transition to the next process, such as hoisting structural components onto fully hardened columns or beams. A long final setting time means that the concrete retains its plasticity for a longer period, making it suitable for concrete construction in the high temperatures of summer and preventing cracks caused by excessively rapid hardening of concrete in hot weather.

[0006] However, the initial and final setting times of existing liquid accelerators cannot be adjusted separately, limiting their adaptability to different construction types. Therefore, providing a liquid accelerator with separately adjustable initial and final setting times is urgently needed. Summary of the Invention

[0007] The purpose of this invention is to solve the problem that the initial setting time and final setting time of existing liquid accelerators cannot be adjusted separately, and to provide a liquid accelerator for concrete with adjustable setting time and its preparation method.

[0008] To achieve the above objectives, the present invention provides a liquid quick-setting agent for concrete with adjustable setting time, comprising the following raw materials in weight percentage: 40%-45% polyaluminum sulfate, 3%-5% phosphoric acid, 0.1%-0.5% reactive initial setting component, 2%-4% final setting component, 1%-2% water-soluble polyvinyl alcohol, and the remainder being water.

[0009] The reactive initial setting component includes: polyethylene glycol diglycidyl ether and dendritic polylysine; the final setting component includes: diethanol monoisopropanolamine and carboxylated tetraethylene glycol monomethyl ether.

[0010] Optionally, the weight percentage of the polyethylene glycol diglycidyl ether is greater than or equal to 0.05% and less than or equal to 0.1%; and the weight percentage of the dendritic polylysine is greater than or equal to 0.05% and less than or equal to 0.2%. This liquid accelerator has a long initial setting time.

[0011] Optionally, the weight percentage of the polyethylene glycol diglycidyl ether is greater than 0.1% and less than or equal to 0.2%; and the weight percentage of the dendritic polylysine is greater than 0.2% and less than or equal to 0.3%. This liquid accelerator has a short initial setting time.

[0012] Optionally, the weight percentage of the diethanol monoisopropanolamine is greater than or equal to 1.5% and less than or equal to 2%; and the weight percentage of the carboxytetraethylene glycol monomethyl ether is greater than or equal to 0.5% and less than or equal to 1%, and the liquid quick-setting agent has a long final setting time.

[0013] Optionally, the weight percentage of the diethanol monoisopropanolamine is greater than 2% and less than or equal to 2.5%; and the weight percentage of the carboxytetraethylene glycol monomethyl ether is greater than 1% and less than or equal to 1.5%, and the liquid quick-setting agent has a short final setting time.

[0014] The present invention also provides a method for preparing the above-mentioned liquid quick-setting agent for concrete with adjustable setting time, comprising the following steps:

[0015] S1, dissolve polyethylene glycol diglycidyl ether and dendritic polylysine in an aqueous phosphoric acid solution;

[0016] S2, add diethanol monoisopropanolamine and carboxytetraethylene glycol monomethyl ether to the solution, then add polyaluminum sulfate and water-soluble polyvinyl alcohol and mix well to obtain the liquid quick-setting agent for concrete with adjustable setting time.

[0017] Compared with the prior art, the beneficial effects of the present invention are:

[0018] (1) The initial setting time and final setting time of the liquid accelerator of the present invention can be controlled separately. Specifically, the initial setting time of the accelerator is controlled by controlling the content of polyethylene glycol diglycidyl ether and dendritic polylysine; the final setting time of the accelerator is controlled by controlling the content of diethanol monoisopropanolamine and carboxytetraethylene glycol monomethyl ether.

[0019] (2) The liquid quick-setting agent of the present invention has good stability and long storage time:

[0020] This invention uses polyaluminum sulfate as a quick-setting agent component, so that aluminum in the solution exists in a polymerized form rather than a free form, thereby reducing the amount of free Al in the solution. 3+ The concentration of Al 3+ It is less prone to supersaturation and crystallization, thus improving the stability of the accelerator.

[0021] Furthermore, the liquid quick-setting agent of the present invention also contains water-soluble polyvinyl alcohol, the hydroxyl groups carried by which the water-soluble polyvinyl alcohol can chelate Al 3+ , making Al 3+ It is less prone to supersaturation and crystallization, further improving the stability of the accelerator.

[0022] (3) The liquid quick-setting agent of the present invention is free of fluorine and alkali, which greatly reduces the harm to the environment. Detailed Implementation

[0023] The technical solution of the present invention will be further described below with reference to the embodiments.

[0024] In existing construction projects, different construction types have different requirements for the initial setting time and final setting time of concrete.

[0025] In some cases, construction projects require concrete to have a short initial setting time and a long final setting time, such as the construction of retaining walls and tunnel linings in the high temperatures of summer. Construction projects need the building to achieve a certain degree of hardness as early as possible (short initial setting time) to avoid deformation caused by external forces in the early stages; and they also need a longer final setting time to prevent the concrete from hardening too quickly and causing cracks in the high temperatures of summer.

[0026] In other cases, construction projects require concrete to have a long initial setting time and a short final setting time, such as complex structures like irregularly shaped columns and densely reinforced beams. These structures typically require a longer time for concrete laying and leveling, necessitating a longer initial setting time. Later in the concrete's setting process, construction workers desire a shorter final setting time to quickly move to the next stage and shorten the overall construction period.

[0027] As described in the background art, the initial setting time and final setting time of existing liquid accelerators are usually not adjustable separately. That is, if the initial setting time of existing liquid accelerators is long, the final setting time is also long; if the initial setting time is short, the final setting time is also short, causing existing accelerators to fail to meet the above-mentioned construction requirements. Based on this, the present invention provides a liquid accelerator for concrete with adjustable setting time, whose initial setting time and final setting time can be adjusted separately.

[0028] This invention provides a liquid quick-setting agent for concrete with adjustable setting time, comprising the following raw materials by weight percentage: 40%-45% polyaluminum sulfate, 3%-5% phosphoric acid, 0.1%-0.5% reactive initial setting component, 2%-4% final setting component, 1%-2% water-soluble polyvinyl alcohol, and the remainder being water. The reactive initial setting component includes polyethylene glycol diglycidyl ether and dendritic polylysine; the final setting component includes diethanol monoisopropanolamine and carboxylated tetraethylene glycol monomethyl ether.

[0029] This invention regulates the initial setting time of a accelerator by adjusting the content of polyethylene glycol diglycidyl ether and dendritic polylysine; and regulates the final setting time by adjusting the content of diethanol monoisopropanolamine and carboxytetraethylene glycol monomethyl ether. The principle is as follows:

[0030] (1) Under acidic conditions of the accelerator, the polyethylene glycol diglycidyl ether and dendritic polylysine of the present invention are stable and do not react, ensuring the storage stability of the liquid accelerator; after the accelerator of the present invention is mixed with concrete, the polyethylene glycol diglycidyl ether and dendritic polylysine react under alkaline conditions of concrete to generate a large number of hydroxyl groups, which promote the formation of CSH gel in the early stage of cement hydration and accelerate the initial setting of cement.

[0031] Specifically, under alkaline conditions, the epoxy groups of polyethylene glycol diglycidyl ether react with the amino groups of dendritic polylysine through a nucleophilic reaction to generate a large number of hydroxyl groups, as shown in the following reaction formula:

[0032]

[0033] Furthermore, the product formed by the reaction of polyethylene glycol diglycidyl ether and dendritic polylysine exhibits a cross-linked network structure, further accelerating the initial setting of concrete. Specifically, during the initial setting of concrete, cement hydration products (such as CSH gel) overlap and form a network between cement particles, binding the cement particles and causing the concrete to initially set. After the cross-linked network structure is formed by the reaction of polyethylene glycol diglycidyl ether and dendritic polylysine in this invention, the cement hydration products can directly grow into a network on this structure, shortening the time for the hydration products to overlap and form a network, allowing the cement particles to set more quickly and shortening the initial setting time of concrete.

[0034] (2) The hydroxyl and tertiary amine groups in diethanol monoisopropanolamine can complex with Ca. 2+ It accelerates the hydration of tricalcium silicate (C3S) and shortens the final setting time.

[0035] C3S is a major component of cement, and it produces OH- upon hydration. - OH -It can accelerate the formation of ettringite (the main contributor to final setting) and shorten the final setting time. During the final setting process of concrete, the surface of cement particles is covered with a hydration passivation film (containing Ca). 2+ Because of the covering, the C3S inside the cement particles cannot come into contact with water and cannot hydrate to form OH-. - Etnacite forms slowly, resulting in a longer final setting time. When the Ca in the solution... 2+ After being complexed with diethanol monoisopropanolamine, free Ca in the solution 2+ As the concentration of Ca decreases, the Ca in the passivation film... 2+ As dissolution begins, the passivation film structure is disrupted, exposing the C3S inside the cement particles, allowing the C3S to react with water to generate OH-. - It promotes the formation of ettringite (AFt) and shortens the final setting time.

[0036] (3) The carboxylate group (–COO) in carboxytetraethylene monomethyl ether - It can complex Al in polyaluminum sulfate 3+ This promotes the addition of Ca in the solution. 2+ Replace the original aluminum ions and SO4 2- This combination promotes the formation of ettringite (C6A·3CaSO4·32H2O) and shortens the final setting time.

[0037] Therefore, this invention can control the initial setting time of the accelerator by adjusting the content of polyethylene glycol diglycidyl ether and dendritic polylysine in the accelerator; and can control the final setting time of the accelerator by adjusting the content of diethanol monoisopropanolamine and carboxytetraethylene glycol monomethyl ether in the accelerator.

[0038] Furthermore, this invention uses polyaluminum sulfate as the main raw material for a liquid quick-setting agent. Compared with traditional aluminum sulfate, the aluminum in polyaluminum sulfate exists in a polymerized form, rather than free Al. 3+ The form reduces the amount of free Al in the solution. 3+ The concentration of Al 3+ It is less prone to supersaturation and crystallization, thus improving the stability of the accelerator.

[0039] This invention uses water-soluble polyvinyl alcohol as a stabilizer and early-strength agent in quick-setting agents. The hydroxyl groups in water-soluble polyvinyl alcohol can chelate Al... 3+ , making Al 3+ It is less prone to supersaturation and crystallization, further improving the stability of the accelerator. In addition, water-soluble polyvinyl alcohol also has good binding properties, which can make the early structure of concrete denser and accelerate the early strength development of concrete.

[0040] This invention uses phosphoric acid as an acidity regulator for the quick-setting agent, making the liquid quick-setting agent of this invention acidic, making it difficult for aluminum ions to hydrolyze and precipitate, and further enhancing the stability of the quick-setting agent.

[0041] The technical solution of the present invention will be further described below with reference to the embodiments.

[0042] Example 1

[0043] This embodiment provides a liquid accelerator for concrete with adjustable setting time. The weight ratio of each raw material is shown in Table 1, with the balance being water. All raw materials used in this embodiment are industrial grade with a purity greater than 95%. Specifically, polyaluminum sulfate was purchased from Shanghai Maclean Biochemical Technology Co., Ltd., diethanolmonoisopropanolamine was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., carboxylated tetraethylene glycol monomethyl ether was purchased from Shanghai Maclean Biochemical Technology Co., Ltd., phosphoric acid was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., water-soluble polyvinyl alcohol was purchased from Shanghai Yuanye Biotechnology Co., Ltd., dendritic polylysine was purchased from Shanghai Yingdong Biotechnology Co., Ltd., and polyethylene glycol diglycidyl ether was purchased from Suzhou Senfida Chemical Co., Ltd.

[0044] The method for preparing the liquid quick-setting agent with adjustable setting time for concrete provided in this embodiment includes the following steps:

[0045] (1) Add water to the acid-resistant stainless steel reactor, set the stirring speed to 150 rpm, add phosphoric acid and stir evenly to form an acidic environment;

[0046] (2) Add polyethylene glycol diglycidyl ether and dendritic polylysine and stir well, then add diethanol monoisopropanolamine and carboxytetraethylene glycol monomethyl ether.

[0047] (3) Finally, add polyaluminum sulfate and water-soluble polyvinyl alcohol (PVA) and stir evenly to obtain the liquid quick-setting agent for concrete with adjustable setting time in this embodiment.

[0048] The reason for adding phosphoric acid first and then polyethylene glycol diglycidyl ether and dendritic polylysine in the above steps is that polyethylene glycol diglycidyl ether and dendritic polylysine are stable and do not react in an acidic environment, resulting in a fast-setting agent with good stability.

[0049] Example 2

[0050] The weight ratio of each raw material in this embodiment is shown in Table 1.

[0051] Example 3

[0052] The weight ratio of each raw material in this embodiment is shown in Table 1.

[0053] Example 4

[0054] The weight ratio of each raw material in this embodiment is shown in Table 1.

[0055] Table 1. Weight ratio of raw materials for each embodiment.

[0056]

[0057] Comparative Example 1

[0058] The difference between this comparative example and Example 2 is that polyethylene glycol diglycidyl ether and dendritic polylysine were not added. The weight ratios of each raw material are shown in Table 2.

[0059] Comparative Example 2

[0060] The difference between this comparative example and Example 2 is that diethanol monoisopropanolamine was not added, and the weight ratio of each raw material is shown in Table 2.

[0061] Comparative Example 3

[0062] The difference between this comparative example and Example 2 is that carboxytetraethylene glycol monomethyl ether was not added, and the weight ratio of each raw material is shown in Table 2.

[0063] Comparative Example 4

[0064] The difference between this comparative example and Example 2 is that water-soluble polyvinyl alcohol was not added, and the weight ratio of each raw material is shown in Table 2.

[0065] Table 2 shows the weight ratio of raw materials for each comparative example.

[0066]

[0067] Comparative Example 5

[0068] SBT®-N(II) Liquid Accelerator (Alkali-Free)

[0069] Performance tests were conducted on each example and comparative example at a dosage of 7%. The initial setting time, final setting time, 1-day compressive strength, 28-day compressive strength ratio, and resilience data of each example and comparative example are shown in Table 3.

[0070] Table 3 Performance test results of each embodiment and comparative example

[0071]

[0072] As can be seen from the table:

[0073] Compared with Example 2, Example 4 reduces the weight ratio of reactive initial setting components (polyethylene glycol diglycidyl ether and dendritic polylysine), resulting in a longer initial setting time and no significant change in final setting time, making it suitable for the construction of complex structures such as irregular columns and densely reinforced beams.

[0074] Compared with Example 2, Example 3 reduces the weight ratio of the final setting components (diethanol monoisopropanolamine and carboxytetraethylene glycol monomethyl ether), resulting in a longer final setting time and no significant change in the initial setting time. It is suitable for the construction of retaining walls and tunnel linings under high-temperature conditions in summer.

[0075] Compared with Example 2, Comparative Example 1 did not contain polyethylene glycol diglycidyl ether or dendritic polylysine, and its initial setting time was significantly longer, exceeding the national standard requirements.

[0076] Compared to Example 2, Comparative Examples 2 and 3, which did not contain diethanol monoisopropanolamine and carboxylated tetraethylene glycol monomethyl ether, respectively, showed significantly longer final setting times, making them unsuitable for practical construction. Furthermore, Comparative Examples 2 and 3 demonstrate that diethanol monoisopropanolamine has a more significant impact on final setting time, while carboxylated tetraethylene glycol monomethyl ether significantly affects rebound rate.

[0077] Compared with Example 2, Comparative Example 4 did not add an early strength agent (water-soluble polyvinyl alcohol), and its strength decreased significantly while its resilience increased significantly.

[0078] Furthermore, as shown in Comparative Example 5, the performance of the accelerator of the present invention is significantly better than that of conventional materials on the market.

[0079] In summary, this invention provides a liquid accelerator for concrete with adjustable setting time and its preparation method. The initial setting time and final setting time of this liquid accelerator can be controlled separately. Specifically, the initial setting time of the accelerator is controlled by adjusting the content of polyethylene glycol diglycidyl ether and dendritic polylysine; the final setting time of the accelerator is controlled by adjusting the content of diethanol monoisopropanolamine and carboxytetraethylene glycol monomethyl ether.

[0080] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A liquid quick-setting agent for concrete with adjustable setting time, characterized in that, The raw materials include the following weight percentages: 40%-45% polyaluminum sulfate, 3%-5% phosphoric acid, 0.1%-0.5% reactive initial setting component, 2%-4% final setting component, 1%-2% water-soluble polyvinyl alcohol, and the remainder is water; The reactive initial setting component includes polyethylene glycol diglycidyl ether and dendritic polylysine; the final setting component includes diethanol monoisopropanolamine and carboxylated tetraethylene glycol monomethyl ether; by controlling the content of the reactive initial setting component, the initial setting time of the liquid accelerator is regulated, and by controlling the content of the final setting component, the final setting time of the liquid accelerator is regulated.

2. The liquid quick-setting agent for concrete with adjustable setting time as described in claim 1, characterized in that, The weight percentage of the reactive initial setting component is greater than or equal to 0.1% and less than or equal to 0.3%.

3. The liquid quick-setting agent for concrete with adjustable setting time as described in claim 2, characterized in that: The weight percentage of the polyethylene glycol diglycidyl ether is greater than or equal to 0.05% and less than or equal to 0.1%; the weight percentage of the dendritic polylysine is greater than or equal to 0.05% and less than or equal to 0.2%.

4. The liquid quick-setting agent for concrete with adjustable setting time as described in claim 1, characterized in that, The weight percentage of the reactive initial setting component is greater than 0.3% and less than or equal to 0.5%.

5. The liquid quick-setting agent for concrete with adjustable setting time as described in claim 4, characterized in that: The weight percentage of the polyethylene glycol diglycidyl ether is greater than 0.1% and less than or equal to 0.2%; the weight percentage of the dendritic polylysine is greater than 0.2% and less than or equal to 0.3%.

6. The liquid quick-setting agent for concrete with adjustable setting time as described in claim 1, characterized in that, The weight percentage of the final setting component is greater than or equal to 2% and less than or equal to 3%.

7. The liquid quick-setting agent for concrete with adjustable setting time as described in claim 6, characterized in that: The weight percentage of the diethanol monoisopropanolamine is greater than or equal to 1.5% and less than or equal to 2%; the weight percentage of the carboxytetraethylene glycol monomethyl ether is greater than or equal to 0.5% and less than or equal to 1%.

8. The liquid quick-setting agent for concrete with adjustable setting time as described in claim 1, characterized in that, The weight percentage of the final setting component is greater than 3% and less than or equal to 4%.

9. The liquid quick-setting agent for concrete with adjustable setting time as described in claim 8, characterized in that: The weight percentage of the diethanol monoisopropanolamine is greater than 2% and less than or equal to 2.5%; the weight percentage of the carboxytetraethylene glycol monomethyl ether is greater than 1% and less than or equal to 1.5%.

10. A method for preparing a liquid accelerator for concrete with adjustable setting time as described in any one of claims 1 to 9, characterized in that, Includes the following steps: S1, dissolve polyethylene glycol diglycidyl ether and dendritic polylysine in an aqueous phosphoric acid solution; S2, add diethanol monoisopropanolamine and carboxytetraethylene glycol monomethyl ether to the solution, then add polyaluminum sulfate and water-soluble polyvinyl alcohol and mix well to obtain the liquid quick-setting agent for concrete with adjustable setting time.

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