Inorganic low-alkali powder quick-setting agent and application method thereof

Abstract

The present application relates to the technical field of concrete admixtures, and specifically discloses an inorganic low-alkali powder accelerator and its application method. The inorganic low-alkali powder accelerator comprises the following components in parts by weight: 36-38 parts of aluminum sulfate, 18-20 parts of waste clay brick powder, and 7.2-7.6 parts of sepiolite powder, wherein the waste clay brick powder is a crushed product of waste clay sintered bricks. The present application utilizes waste clay brick powder to absorb polycarboxylic acid water reducer in concrete mixture, which hinders the polycarboxylic acid water reducer from playing a retarding effect, thereby alleviating the obstruction caused by the polycarboxylic acid water reducer to the accelerating effect of the accelerator, and the waste clay brick powder accelerates the dissolution of C3S after consuming calcium hydroxide, which also enhances the accelerating effect of the accelerator.

Description

Technical Field

[0001] The present application relates to the technical field of concrete admixtures, and more specifically, to an inorganic low-alkali powder quick-setting agent and an application method thereof. Background Art

[0002] Shotcrete refers to concrete that is constructed by spraying, which can realize many projects that cannot be completed by traditional construction methods. The most important component in shotcrete is the accelerator, which can make cement concrete coagulate quickly, thereby increasing the thickness of the first spray layer and shortening the time interval between two sprayings. Improving the accelerating coagulation performance of the accelerator is crucial to the construction quality of shotcrete.

[0003] In the related art, there is an inorganic low-alkali liquid accelerating agent, which includes the following components by weight: 36-38 parts of aluminum sulfate, 7.2-7.6 parts of sepiolite powder, 1.0-1.1 parts of triethanolamine, 3-6 parts of glycerol, and 80-100 parts of water. In actual application, the amount of accelerating agent used is 8% of the total weight of cement in concrete.

[0004] With respect to the above-mentioned related technologies, the inventors believe that although aluminum sulfate in the related technologies can play a certain role in accelerating coagulation, in concrete containing polycarboxylic acid water-reducing agent, the retarding effect of the polycarboxylic acid water-reducing agent will prolong the setting time of the concrete mixture, limiting the normal performance of the accelerating effect of the accelerator, which is not conducive to accelerating the coagulation of the concrete mixture. Summary of the invention

[0005] In the related art, the retarding effect of polycarboxylic acid water-reducing agent will prolong the setting time of concrete mixture, limit the normal performance of the accelerating effect of the setting agent, and is not conducive to accelerating the setting of concrete mixture. In order to improve this defect, the present application provides an inorganic low-alkali powder setting agent and its application method.

[0006] In the first aspect, the present application provides an inorganic low-alkali powder accelerating setting agent, which adopts the following technical solution:

[0007] An inorganic low-alkali powder quick-setting agent comprises the following components in parts by weight: 36-38 parts of aluminum sulfate, 18-20 parts of waste clay brick powder, and 7.2-7.6 parts of sepiolite powder, wherein the waste clay brick powder is a crushed product of waste clay sintered bricks.

[0008] By adopting the above technical scheme, the present application adds waste clay brick powder to the components of the accelerating agent. The main component of the waste clay brick powder is clay mineral particles, and clay mineral particles are more likely to adsorb polycarboxylic acid water reducers than cement particles. Therefore, in the concrete mixture containing the accelerating agent of the present application, the waste clay brick powder can adsorb the polycarboxylic acid water reducer, and the amount of polycarboxylic acid water reducer in concrete is limited, usually not exceeding 5% of the total amount of cementitious materials, thereby reducing the possibility of the polycarboxylic acid water reducer combining with cement particles, thereby making it impossible to give full play to the retarding effect of the polycarboxylic acid water reducer. At the same time, in the concrete mixture, a part of the components in the waste clay brick powder can be hydrated and consume calcium hydroxide, which not only reduces the pH of the concrete mixture, but also accelerates the dissolution of C3S. C3S is the main component of cement hydration, so the acceleration of the dissolution rate of C3S increases the hydration rate of cement, thereby improving the accelerating effect of the accelerating agent.

[0009] Preferably, the inorganic low-alkali powder quick-setting agent comprises the following components in parts by weight: 36.5-37.5 parts of aluminum sulfate, 18.5-19.5 parts of waste clay brick powder, and 7.3-7.5 parts of sepiolite powder.

[0010] By adopting the above technical solution, the present application optimizes the components of the accelerating setting agent, which helps to improve the accelerating setting effect of the accelerating setting agent.

[0011] Preferably, the inorganic low-alkali powder quick-setting agent further comprises modified slag, and the modified slag is prepared according to the following method:

[0012] (1) Mixing construction waste soil and sodium sulfate to obtain a primary mixture; in this step, the construction waste soil is Q4 grade loess; in this step, the amount of sodium sulfate used is 6.6-8.4% of the weight of the construction waste soil;

[0013] (2) mixing the primary mixed material with water in a weight ratio of (4.8-5.2):1, and then standing for 3-5 days to obtain an aged material;

[0014] (3) Drying the aged material to constant weight, and then grinding the dried product to obtain modified slag.

[0015] By adopting the above technical scheme, the present application uses a mixture of neutral salt sodium sulfate and construction waste, and after aging, the construction waste fully absorbs sodium sulfate and water, and after drying, the modified waste is obtained. In the concrete mixture, a large amount of calcium ions will be produced due to cement hydration, and the sodium ions in the modified waste can exchange and adsorb with free calcium ions. The modified waste reduces the free calcium ion content in the concrete mixture through exchange adsorption, destroys the calcium-silicon double layer around the C3S particles, and reduces the resistance of the calcium-silicon double layer to the hydration of C3S, thereby accelerating the coagulation of the concrete mixture.

[0016] Preferably, the aging material is dried by freeze drying.

[0017] By adopting the above technical solution, freeze drying can increase the interlayer distance of the slag particles, help improve the ability of the modified slag to exchange calcium ions, help increase the hydration rate of C3S, and accelerate the coagulation of the concrete mixture.

[0018] Preferably, the average particle size of the construction waste is 34-72 μm.

[0019] By adopting the above technical solution, the average particle size of the construction waste is optimized. Within this particle size range, the exchange effect between the sodium ions in the modified waste and the external calcium ions is better. When the average particle size of the construction waste is too large, the specific surface area of ​​the construction waste is small, so the ability of the sodium ions in the modified waste to exchange with the calcium ions in the concrete mixture is poor. When the average particle size of the construction waste is too small, the modified waste is prone to agglomeration, resulting in limited ability of the sodium ions in the modified waste to exchange with the calcium ions in the concrete mixture.

[0020] Preferably, in the inorganic low-alkali powder quick-setting agent formula, the weight proportion of modified slag is 10-30 parts.

[0021] By adopting the above technical solution, the dosage range of modified slag is optimized, which helps to accelerate the coagulation of concrete mixture.

[0022] Preferably, the inorganic low-alkali powder accelerating setting agent further comprises nano silicon dioxide.

[0023] By adopting the above technical solution, nano-silicon dioxide can significantly increase the water demand of cement, thereby reducing the free water in the concrete mixture, reducing the actual water-cement ratio of the concrete mixture, increasing the viscosity of the cement slurry, reducing the rebound of the shotcrete, accelerating the coagulation of the concrete mixture, and improving the accelerating effect of the accelerator. In addition, the waste clay brick powder will reduce the cumulative heat of hydration in the concrete mixture, and nano-silicon dioxide can increase the total amount of heat released by the hydration of silicate cement, realizing the compensation of the heat release. The increase in the heat of hydration also helps to accelerate the coagulation of the concrete mixture.

[0024] Preferably, the dosage of the nano silicon dioxide is 16-28% of the weight of the waste clay brick powder.

[0025] By adopting the above technical solution, the dosage of nano silicon dioxide is optimized and the accelerating effect of the quick-setting agent is improved.

[0026] In a second aspect, the present application provides an application method of an inorganic low-alkali powder accelerating setting agent, which adopts the following technical solution.

[0027] An application method of an inorganic low-alkali powder accelerating setting agent comprises the following steps:

[0028] (1) Mixing the above-mentioned inorganic low-alkali powder accelerating setting agent with silicate cement, coarse aggregate and fine aggregate to obtain dry material; mixing the polycarboxylate water reducer with water to obtain a water reducer solution; in this step, the dosage of the inorganic low-alkali powder accelerating setting agent is 3-5% of the total weight of the silicate cement;

[0029] (2) dry-mixing the dry materials, then adding the water reducing agent solution and continuing to stir to obtain a concrete mixture;

[0030] (3) The concrete mixture is sprayed and cured to obtain a sprayed concrete structure.

[0031] By adopting the above technical scheme, the application method of the inorganic low-alkali powder accelerator is optimized. By using the accelerator of the present application together with the polycarboxylic acid water-reducing agent, the retarding effect of the polycarboxylic acid water-reducing agent is reduced, and the accelerating effect of the accelerator is fully exerted.

[0032] Preferably, the inorganic low-alkali powder quick-setting agent further comprises lithium bromide, and the amount of lithium bromide used is 32-40% of the weight of the waste clay brick powder.

[0033] By adopting the above technical solution, lithium bromide can promote the early release of concrete hydration heat, which is beneficial to shortening the coagulation of concrete mixture. At the same time, lithium bromide will also increase the dissolution of calcium hydroxide, making the calcium-silicon double layer on the surface of C3S more difficult to destroy, which is not conducive to the hydration of C3S. After optimization, when the amount of lithium bromide is 32-40% of the weight of the waste clay brick powder, the overall effect of the quick-setting agent is relatively good.

[0034] In summary, this application has the following beneficial effects:

[0035] 1. The present application utilizes waste clay brick powder to absorb polycarboxylic acid water reducer in concrete mixture, which hinders the polycarboxylic acid water reducer from playing a retarding effect, thereby alleviating the obstruction of the polycarboxylic acid water reducer on the accelerating effect of the accelerator. Moreover, the waste clay brick powder consumes calcium hydroxide to accelerate the dissolution of C3S, which also enhances the accelerating effect of the accelerator.

[0036] 2. In the present application, the preferred components of the inorganic low-alkali powder quick-setting agent also include modified slag, and a preparation method of the modified slag is disclosed. The modified slag absorbs sodium sulfate during the aging process and can exchange and adsorb with free calcium ions in the concrete, thereby reducing the total amount of free calcium ions in the concrete mixture and reducing the hindrance of the calcium-silicon double layer to the hydration of C3S, thereby accelerating the coagulation of the concrete mixture.

[0037] 3. This application uses a low-alkali powder accelerator together with a polycarboxylic acid water-reducing agent, which reduces the retarding effect of the polycarboxylic acid water-reducing agent, thereby giving full play to the accelerating effect of the accelerator. DETAILED DESCRIPTION

[0038] The present application is further described in detail below in conjunction with embodiments, preparation examples and comparative examples. The raw materials involved in the present application can all be obtained commercially.

[0039] Example

[0040] Examples 1-5

[0041] The following description is given by taking Example 1 as an example.

[0042] Example 1

[0043] In this embodiment, the inorganic low-alkali powder quick-setting agent includes the following components: 36 kg of aluminum sulfate, 18 kg of waste clay brick powder, and 7.2 kg of sepiolite powder. The waste clay bricks are waste clay bricks taken from the demolition of brick-concrete structure buildings, with an average particle size of 460 μm. The chemical composition of the waste clay brick powder includes 65.7% SiO2 and 17.8% Al2O3.

[0044] The application method of the inorganic low-alkali powder accelerating setting agent comprises the following steps:

[0045] (1) Mixing an inorganic low-alkali powdered accelerating setting agent with 370 kg of P.O42.5 silicate cement, 1060 kg of coarse aggregate, and 849 kg of fine aggregate to obtain a dry material; mixing 3.7 kg of a polycarboxylic acid water reducer with 103 kg of water to obtain a water reducer solution; in this step, the dosage of the inorganic low-alkali powdered accelerating setting agent is 4% of the weight of the silicate cement;

[0046] (2) dry-mixing the dry materials, then adding the water reducing agent solution and continuing to stir to obtain a concrete mixture;

[0047] (3) The concrete mixture is sprayed and cured to obtain a sprayed concrete structure.

[0048] As shown in Table 1, the difference between Examples 1-5 mainly lies in the different raw material ratios of the inorganic low-alkali powder accelerating setting agent.

[0049] Table 1

[0050]

[0051]

[0052] Example 6

[0053] The difference between this embodiment and embodiment 4 is that the components of the inorganic low-alkali powder quick-setting agent also include 5 kg of modified slag, and the modified slag is prepared according to the following method:

[0054] (1) Mixing construction waste soil with an average particle size of 30 μm with sodium sulfate to obtain a primary mixture; in this step, the construction waste soil is Q4 grade loess; in this step, the amount of sodium sulfate used is 7.2% of the weight of the construction waste soil;

[0055] (2) mixing the primary mixed material with water in a weight ratio of 5:1, and then leaving it to stand for 4 days to obtain an aged material;

[0056] (3) Drying the aged material at 105° C. to constant weight, and then grinding the dried product to obtain modified slag.

[0057] Example 7

[0058] The difference between this embodiment and embodiment 6 is that the drying method of the aged material is not oven drying, but freeze drying at -40°C to constant weight.

[0059] Embodiment 8-11

[0060] As shown in Table 2, the difference between Examples 8-11 and Example 7 is that the average particle size of the construction waste is different.

[0061] Table 2 Average particle size of construction waste

[0062] sample Example 7 Example 8 Example 9 Example 10 Embodiment 11 Average particle size / μm 30 34 53 72 80

[0063] As shown in Table 3, the difference between Examples 12-15 and Example 6 is that the amount of modified slag used is different.

[0064] Table 3 Amount of modified slag

[0065] sample Example 6 Example 12 Embodiment 13 Embodiment 14 Embodiment 15 Modified slag / kg 5 10 20 30 35

[0066] Example 16

[0067] The difference between this embodiment and embodiment 4 is that the inorganic low-alkali powder quick-setting agent further comprises nano-silicon dioxide, and the amount of nano-silicon dioxide used is 10% of the weight of the waste clay brick powder.

[0068] As shown in Table 4, the difference between Examples 16-20 is that the percentage of the amount of nano-silicon dioxide used in the weight of the waste clay brick powder is different.

[0069] Table 4 The percentage of nano-silicon dioxide usage in the weight of waste clay brick powder

[0070] sample Example 16 Embodiment 17 Embodiment 18 Embodiment 19 Embodiment 20 Nano-silicon dioxide dosage / % 10 16 22 28 35

[0071] Embodiment 21

[0072] The difference between this embodiment and embodiment 4 is that the inorganic low-alkali powder quick-setting agent further comprises lithium bromide, and the amount of lithium bromide used is 30% of the weight of the waste clay brick powder.

[0073] As shown in Table 5, the difference between Examples 21-25 is that the percentage of lithium bromide used in the weight of the waste clay brick powder is different.

[0074] Table 5 The percentage of lithium bromide used in the weight of waste clay brick powder

[0075] sample Embodiment 21 Embodiment 22 Embodiment 23 Embodiment 24 Embodiment 25 Lithium bromide dosage / % 30 32 35 40 45

[0076] Comparative Example

[0077] Comparative Example 1

[0078] An inorganic low-alkali liquid quick-setting agent comprises the following components in parts by weight: 37 kg of aluminum sulfate, 7.4 kg of sepiolite powder, 1.1 kg of triethanolamine, 4.5 kg of glycerol and 92 kg of water.

[0079] The application method comprises the following steps:

[0080] (1) 370 kg of P.O42.5 silicate cement, 1060 kg of coarse aggregate, and 849 kg of fine aggregate were mixed to obtain a dry material; 3.7 kg of polycarboxylate water reducer was mixed with 103 kg of water to obtain a water reducer solution;

[0081] (2) dry-mixing the dry materials, then adding a water reducing agent solution and an inorganic low-alkali liquid accelerating agent and continuing to stir to obtain a concrete mixture; in this step, the amount of the inorganic low-alkali liquid accelerating agent is 8% of the weight of the silicate cement;

[0082] (3) The concrete mixture is sprayed and cured to obtain a sprayed concrete structure.

[0083] Comparative Example 2

[0084] The difference between this comparative example and Example 4 is that in the application method of the inorganic low-alkali powder accelerating setting agent, the weight of the polycarboxylate water-reducing agent contained in the concrete mixture is 9.5 kg.

[0085] Performance testing methods

[0086] The concrete mixture was produced according to the application method of each embodiment and comparative example, and then the setting time of the concrete mixture was tested with reference to the "GB / T50080-2016 Standard for Test Methods for Performance of Ordinary Concrete Mixtures". After the test, the ratio of the setting time of each embodiment and comparative example to the setting time of comparative example 1 was calculated, and the calculation result was defined as the relative setting time, as shown in Table 6.

[0087] Table 6 Relative coagulation time

[0088]

[0089]

[0090] Combining Examples 1-5 and Comparative Example 1 and Table 6, it can be seen that the relative setting time measured in Examples 1-5 is less than that in Comparative Example 1, indicating that the waste clay brick powder can adsorb the polycarboxylic acid water-reducing agent, limiting the retarding effect of the polycarboxylic acid water-reducing agent, and after the waste clay brick powder participates in hydration, it accelerates the dissolution of C3S by consuming calcium hydroxide, thereby increasing the hydration rate of cement and improving the accelerating effect of the quick-setting agent.

[0091] It can be seen from Example 4, Comparative Example 2 and Table 6 that after increasing the amount of the polycarboxylate water-reducing agent in Example 4, the retarding effect of the polycarboxylate water-reducing agent is enhanced, thereby extending the setting time of the concrete mixture.

[0092] Combining Example 4 and Example 6 and Table 6, it can be seen that the relative setting time measured in Example 6 is less than that in Example 4, indicating that the sodium ions in the modified slag reduce the calcium ion concentration in the concrete mixture through exchange adsorption, promote the destruction of the calcium-silicon double layer around the C3S particles, and reduce the obstacle of the calcium-silicon double layer to the hydration of C3S, thereby accelerating the setting of the concrete mixture.

[0093] It can be seen from Example 6, Example 7 and Table 6 that freeze drying can increase the interlayer distance of the slag particles, help improve the ability of the modified slag to exchange calcium ions, help increase the hydration rate of C3S, and accelerate the coagulation of the concrete mixture.

[0094] It can be seen from Example 7, Example 8-11 and Table 6 that when the average particle size of the construction waste is greater than 72 μm, the specific surface area of ​​the construction waste is small, so the ability of the sodium ions in the modified waste to exchange with the calcium ions in the concrete mixture is poor. When the average particle size of the construction waste is less than 34 μm, the modified waste is prone to agglomeration, resulting in limited ability of the sodium ions in the modified waste to exchange with the calcium ions in the concrete mixture.

[0095] Combining Example 6, Examples 12-15 and Table 6, it can be seen that the effect is better when the amount of modified slag is between 10-30 parts. When it is lower than this range, the accelerating effect of the accelerator is limited, and when it is higher than this range, the degree of improvement of the accelerating effect is small.

[0096] It can be seen from Example 4, Examples 16-20 and Table 6 that the relative setting time measured in Examples 16-20 is lower than that in Example 4, indicating that nano-silicon dioxide increases the water demand of cement, thereby reducing the free water in the concrete mixture, reducing the actual water-cement ratio of the concrete mixture, increasing the viscosity of the cement slurry, accelerating the setting of the concrete mixture, and improving the accelerating effect of the accelerating setting agent.

[0097] It can be seen from Example 4, Examples 21-25 and Table 6 that the relative setting time measured in Examples 21-25 is lower than that in Example 4, indicating that the increase in the amount of lithium bromide can promote the early release of concrete hydration heat, which is beneficial to shortening the setting of the concrete mixture. At the same time, the increase in the amount of lithium bromide will also increase the amount of calcium hydroxide dissolved, making the calcium-silicon double layer on the surface of C3S more difficult to destroy, which is not conducive to the hydration of C3S. When the amount of lithium bromide is less than 32% or greater than 40% of the weight of the waste clay brick powder, the accelerating effect of the accelerator is relatively poor, so the preferred dosage range is 32-40%.

[0098] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. An inorganic low-alkali powder quick-setting agent, characterized in that: The inorganic low-alkali powder quick-setting agent comprises the following components in parts by weight: 36.5-37.5 parts of aluminum sulfate, 18.5-19.5 parts of waste clay brick powder, and 7.3-7.5 parts of sepiolite powder. The waste clay brick powder is a crushed product of waste clay sintered bricks, and the chemical composition of the waste clay brick powder includes 65.7% SiO2 and 17.8% Al2O3. The components of the inorganic low-alkali powder quick-setting agent also include modified slag, and the modified slag is prepared according to the following method: (1) Mixing construction waste soil and sodium sulfate to obtain a primary mixture; in this step, the construction waste soil is Q4 grade loess; in this step, the amount of sodium sulfate used is 6.6-8.4% of the weight of the construction waste soil; (2) Mixing the primary mixed material with water in a weight ratio of (4.8-5.2):1, and then letting it stand for 3-5 days to obtain an aged material; (3) Drying the aged material to constant weight, and then grinding the dried product to obtain modified slag.

2. The inorganic low-alkali powder quick-setting agent according to claim 1, characterized in that: The drying method of the aged material is freeze drying.

3. The inorganic low-alkali powder quick-setting agent according to claim 2, characterized in that: The average particle size of the construction waste is 34-72 μm.

4. The inorganic low-alkali powder quick-setting agent according to claim 1, characterized in that: In the inorganic low-alkali powder quick-setting agent formula, the weight proportion of modified slag is 10-30 parts.

5. The inorganic low-alkali powder quick-setting agent according to claim 1, characterized in that: The inorganic low-alkali powder quick-setting agent also includes nano silicon dioxide as a component.

6. The inorganic low-alkali powder quick-setting agent according to claim 5, characterized in that: The dosage of the nano silicon dioxide is 16-28% of the weight of the waste clay brick powder.

7. An application method of an inorganic low-alkali powder accelerating setting agent, characterized in that: The following steps are involved: (1) Mixing the inorganic low-alkali powdered accelerating setting agent according to any one of claims 1 to 6 with silicate cement, coarse aggregate and fine aggregate to obtain a dry material; mixing a polycarboxylate water reducer with water to obtain a water reducer solution; in this step, the dosage of the inorganic low-alkali powdered accelerating setting agent is 3-5% of the total weight of the silicate cement; (2) Dry-mixing the dry materials, then adding the water reducing agent solution and continuing to stir to obtain a concrete mixture; (3) The concrete mixture is sprayed and cured to obtain a sprayed concrete structure.

8. The application method of the inorganic low-alkali powder quick-setting agent according to claim 7, characterized in that: The inorganic low-alkali powder quick-setting agent also includes lithium bromide, and the amount of lithium bromide used is 32-40% of the weight of the waste clay brick powder.

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