Waterproof dense setting accelerator as well as preparation method and application thereof

Abstract

The invention relates to the technical field of concrete admixtures, and particularly discloses a waterproof dense setting accelerator and a preparation method and application thereof, the waterproof dense setting accelerator comprises the following components by weight: 5-10 parts of a suspending agent, 50-250 parts of modified silica sol, 100-250 parts of an organic complex waterproof agent, 400-600 parts of a setting accelerator, and water; wherein the modified silica sol is obtained by modifying acidic silica sol with a modifier, and the modifier is a silane coupling agent; wherein the organic complexing waterproofing agent is a higher fatty acid aluminum complex. After the waterproof dense setting accelerator is doped into concrete, a large amount of air entraining of the concrete cannot be caused, microcracks of sprayed concrete can be filled, the compactness of the concrete is further improved, meanwhile, a hydrophobic effect is formed in the sprayed concrete and on the surface of the sprayed concrete, and the addition of the organic complexing waterproof agent can promote the condensation of the concrete, so that the waterproof performance of the concrete is improved. And the concrete can be quickly coagulated by matching with a coagulant.

Description

Technical Field

[0001] The present invention relates to the technical field of concrete admixtures, and in particular to a waterproof and dense quick-setting agent, a preparation method thereof, and an application thereof. Background Art

[0002] Shotcrete is a type of concrete that is sprayed onto the surface at high speed using a spraying device and then quickly solidifies and hardens. It is widely used in tunnel engineering, water conservancy projects, coal mine construction, mine restoration, and slope protection. Because shotcrete uses high-pressure air to blow concrete at high speed onto the inner wall of the tunnel, without the conventional vibration process of concrete, the shotcrete has poor density after solidification and is prone to many voids. The environment in the tunnel is harsh, and substances such as water and inorganic salts in the mountain constantly erode the shotcrete structure. In addition, the shotcrete itself has many voids and lacks density, which leads to severe corrosion of the steel bars, arch frames, and other parts in the shotcrete. The occurrence of this situation seriously weakens the support effect of the shotcrete and shortens the service life of the tunnel.

[0003] CN201910533370.4 provides a waterproof alkali-free liquid quick-setting agent with a water-reducing function. The waterproof quick-setting agent uses lithium stearate, which is formed by the reaction of stearic acid and lithium hydroxide, as raw material. This substance has strong surface activity and will entrain a large amount of air in the shotcrete, causing the concrete density to deteriorate and the strength to decrease.

[0004] CN202410130511.9 also provides a waterproof powder quick-setting agent, which uses hydroxyethyl cellulose to modify stearic acid, and will also entrain a large amount of air in the concrete, causing the concrete density to deteriorate and the strength to decrease. Summary of the Invention

[0005] The object of the present invention is to provide a waterproof and dense quick-setting agent which, after being added to concrete, does not cause a large amount of air entrainment in the concrete, thereby solving the problem of poor compactness caused by the addition of existing quick-setting agents to concrete, and can achieve rapid solidification of concrete, so that a hydrophobic effect is formed both inside and on the surface of the shotcrete.

[0006] In addition, the present invention also provides a preparation method and application of the waterproof and dense quick-setting agent.

[0007] The present invention is achieved through the following technical solutions: A waterproof and dense quick-setting agent, comprising the following components in parts by weight: 5-10 parts of suspending agent, 50-250 parts of modified silica sol, 100-250 parts of organic complex waterproofing agent, 400-600 parts of coagulant, water; Wherein, the modified silica sol is obtained by modifying the acidic silica sol with a modifier, and the modifier is a silane coupling agent; Among them, the organic complex waterproofing agent is a higher fatty acid aluminum complex.

[0008] The present invention obtains a modified silica sol by modifying the acidic silica sol with a silane coupling agent. The silanol groups in the coupling agent condense with the hydroxyl groups on the surface of the acidic silica sol, blocking some of the hydroxyl groups in the acidic silica sol, preventing the acidic silica sol from self-aggregating, and improving the stability of the acidic silica sol. In addition, the lipophilic component in the coupling agent imparts a certain water-repellent property to the acidic silica sol. Therefore, the introduction of the modified silica sol not only fills microcracks in shotcrete, but also reacts with calcium hydroxide produced by cement hydration to form calcium silicate hydrate, thereby improving the strength of the shotcrete.

[0009] The organic complex waterproofing agent of the present invention is a higher fatty acid aluminum complex, and its chain alkyl group has an excellent hydrophobic effect. In the sprayed concrete system, this component can complex with calcium ions generated by cement hydration to form a higher fatty acid calcium waterproofing material, and the released aluminum ions can participate in the coagulation of the sprayed concrete.

[0010] In summary, the waterproof and dense quick-setting agent of the present invention, after being added to concrete, will not cause a large amount of air entrainment in the concrete, and can fill the microcracks of the shotcrete, thereby improving the density of the concrete. At the same time, the organic complex waterproofing agent and the modified silica sol can achieve the waterproof and water-repellent properties of the concrete, and realize the formation of a hydrophobic effect both inside and on the surface of the shotcrete. The addition of the organic complex waterproofing agent can promote the coagulation of the concrete, and can achieve rapid coagulation of the concrete in combination with the coagulant.

[0011] Specifically, the preparation process of modified silica sol is as follows: After heating 500-600 parts of 30% acidic silica sol in a water bath to 40-45°C, add 200-250 parts of a modifier and 150-200 parts of ethanol and react for 1-1.5 hours to obtain a modified silica sol. The silane coupling agent used for modification includes at least one of tridecafluorooctyltriethoxysilane and n-octyltriethoxysilane.

[0012] Specifically, the preparation process of the organic complex waterproofing agent is as follows: 20-30 parts of amorphous aluminum hydroxide are slowly added into 80-100 parts of an organic acid complexing agent and slowly stirred for 3-4 hours to obtain an organic complexing waterproofing agent, wherein the organic acid complexing agent includes at least one of oleic acid and erucic acid.

[0013] In a preferred embodiment, the preparation process of the coagulant is as follows: Mix 180-250 parts of water, 100-130 parts of aluminum hydroxide, 200-280 parts of 40% by mass silicofluoric acid, and 300-400 parts of aluminum sulfate, heat in a water bath to 80-85°C, stir and react for 2-3 hours, add 50-80 parts of sodium aluminate solution, continue stirring for 1-1.5 hours, cool, and obtain a coagulant.

[0014] The coagulant prepared by the above method can well achieve the coagulation of concrete.

[0015] In a preferred embodiment, the preparation process of sodium metaaluminate solution is as follows: Mix 250 parts of sodium hydroxide, 400 parts of aluminum hydroxide, and 350 parts of water, heat in an oil bath to 110-115°C, and react for 1.5-2 hours to obtain a sodium metaaluminate solution.

[0016] In a preferred embodiment, the suspending agent is a modified suspending agent obtained by silane coupling modification, and the suspending agent is hydrated magnesium silicate.

[0017] Specifically, the preparation process of the modified suspending agent is as follows: The silane coupling agent KH-550 is dissolved in an ethanol aqueous solution, added into a suspending agent, and the surface of the suspending agent is modified at room temperature and stirred for 1-1.5 hours to obtain a modified suspending agent.

[0018] The present invention modifies the surface of the suspending agent by silane coupling, so that the surface of the suspending agent has a slight oleophilic effect, enhances its affinity with the modified silica sol and the organic complex waterproofing agent, and prevents the suspension from stratification.

[0019] The preparation method of the above-mentioned waterproof dense type quick-setting agent comprises the following steps: Add water to the container, start high-speed dispersion, add suspending agent, stir for 0.5-1h, then add organic complex waterproofing agent, continue to disperse for 1-1.5h, add modified silica sol and coagulant, continue to disperse for 2-3h to obtain a waterproof and dense quick-setting agent.

[0020] The application of the above-mentioned waterproof and dense quick-setting agent in the preparation of shotcrete.

[0021] Compared with the prior art, the present invention has the following advantages and beneficial effects: The waterproof, compacting quick-setting agent of the present invention contains a waterproof component that, when added to shotcrete, reacts with calcium ions in the concrete to form a calcium complex, transforming the concrete from hydrophilic to hydrophobic. In addition to rapidly solidifying the shotcrete, the waterproof, compacting quick-setting agent increases its density, reduces micropores in the shotcrete, and creates a hydrophobic effect both within and on the surface of the shotcrete, making it difficult for water to penetrate the concrete and preventing corrosion of the concrete and steel bars by water and its inorganic salts. This waterproof quick-setting agent significantly improves the durability of shotcrete and has broad application prospects in this field. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings: Figure 1 This is a picture of a mortar test block prepared by adding the quick-setting agent prepared in Example 1 of the present invention after dripping water; Figure 2 This is a picture of a mortar test block prepared by adding the quick-setting agent prepared in Example 2 of the present invention after dripping water; Figure 3 This is a picture of a mortar test block prepared by adding the quick-setting agent prepared in Example 3 of the present invention after dripping water; Figure 4 This is a picture of a mortar test block prepared by adding the quick-setting agent prepared in Example 4 of the present invention after dripping water; Figure 5 This is a picture of a mortar test block prepared by adding the quick-setting agent prepared in Example 5 of the present invention after dripping water; Figure 6 This is a picture of a mortar test block prepared by adding the quick-setting agent prepared in Comparative Example 1 of the present invention after dripping water; Figure 7 This is a picture of a mortar test block prepared by adding the quick-setting agent prepared in Comparative Example 2 of the present invention after dripping water; Figure 8 This is a picture of a mortar test block prepared by adding the quick-setting agent prepared in Comparative Example 3 of the present invention after dripping water. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with the examples. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention. The embodiments described below are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0024] In the following description, numerous specific details are set forth to provide a thorough understanding of the present invention. However, it will be apparent to one of ordinary skill in the art that these specific details are not necessarily required to practice the present invention. In other examples, well-known structures, materials, or methods are not specifically described to avoid obscuring the present invention. The materials, instruments, and reagents used in the following examples, unless otherwise specified, are commercially available. The techniques used in the examples, unless otherwise specified, are conventional techniques well known to those skilled in the art.

[0025] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. Throughout the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0026] Example: In order to solve the problem that the existing accelerating setting agent deteriorates the density and reduces the strength of concrete after being added to concrete, this embodiment provides a waterproof and dense accelerating setting agent, which includes the following components in parts by weight: 5-10 parts of suspending agent, 50-250 parts of modified silica sol, 100-250 parts of organic complex waterproofing agent, 400-600 parts of coagulant, and water.

[0027] The modified silica sol is obtained by modifying acidic silica sol with a modifier, which is a silane coupling agent. The preparation process of the modified silica sol is as follows: 500-600 parts of 30% acidic silica sol are heated in a water bath to 40-45°C, 200-250 parts of the modifier and 150-200 parts of ethanol are added, and the mixture is reacted for 1-1.5 hours to obtain the modified silica sol. The silane coupling agent used for modification includes at least one of tridecafluorooctyltriethoxysilane and n-octyltriethoxysilane.

[0028] Among them, the organic complex waterproofing agent is a higher fatty acid aluminum complex; the preparation process of the organic complex waterproofing agent is as follows: 20 to 30 parts of amorphous aluminum hydroxide are slowly added to 80 to 100 parts of an organic acid complexing agent, and slowly stirred for 3 to 4 hours to obtain an organic complex waterproofing agent, and the organic acid complexing agent includes at least one of oleic acid and erucic acid.

[0029] Among them, the role of the coagulant is to promote the coagulation of concrete. The preparation process of the coagulant is as follows: Mix 180-250 parts of water, 100-130 parts of aluminum hydroxide, 200-280 parts of 40% by mass silicofluoric acid, and 300-400 parts of aluminum sulfate, heat in a water bath to 80-85°C, stir and react for 2-3 hours, add 50-80 parts of sodium aluminate solution, continue stirring for 1-1.5 hours, cool, and obtain a coagulant.

[0030] Wherein, the preparation process of sodium metaaluminate solution is as follows: Mix 250 parts of sodium hydroxide, 400 parts of aluminum hydroxide, and 350 parts of water, heat in an oil bath to 110-115°C, and react for 1.5-2 hours to obtain a sodium metaaluminate solution.

[0031] The suspending agent serves to prevent the suspension from separating into separate layers. In a preferred embodiment, the suspending agent is a modified suspending agent obtained by silane coupling modification, and the suspending agent is hydrated magnesium silicate. The modified suspending agent is prepared as follows: silane coupling agent KH-550 is dissolved in an ethanol aqueous solution, the suspending agent is added, the suspending agent is surface-modified at room temperature, and the mixture is stirred for 1-1.5 hours to obtain the modified suspending agent.

[0032] The waterproof, compacting quick-setting agent of this embodiment is added to sprayed concrete. In addition to enabling rapid solidification of the sprayed concrete, it can also improve the compactness of the sprayed concrete, reduce bubbles and microcracks, and increase the strength of the sprayed concrete. The waterproof component in the quick-setting agent can react with the calcium ions in the concrete to form a calcium complex, changing the concrete from hydrophilic to hydrophobic. The effects of this waterproof, compacting quick-setting agent are: 1) Modifying the acidic silica sol: The surface of the acidic silica sol is modified using silane coupling agents such as tridecafluorooctyltriethoxysilane and n-octyltriethoxysilane. The silanol groups in the silane coupling agent condense with the hydroxyl groups on the surface of the silica sol, blocking some of the hydroxyl groups in the silica sol, preventing the silica sol from self-aggregating and improving the stability of the acidic silica sol. In addition, the lipophilic components in the coupling agent give the silica sol certain water-repellent properties. The introduction of silica sol not only fills microcracks in shotcrete, but also reacts with calcium hydroxide produced by cement hydration to form calcium silicate hydrate, thereby improving the strength of the shotcrete.

[0033] 2) Prepare an organic complex waterproofing agent and disperse it into the accelerator at high speed. The organic complex waterproofing agent is a higher fatty acid aluminum complex. The long-chain alkyl group has an excellent hydrophobic effect. This component can complex with the calcium ions produced by cement hydration in the shotcrete system to form a higher fatty acid calcium waterproofing material. The released aluminum ions can participate in the coagulation of the shotcrete.

[0034] 3) By modifying the surface of the suspending agent, the surface of the suspending agent has a slight oleophilic effect, which enhances its affinity with the modified silica sol and organic complex waterproofing agent and prevents the suspension from stratification.

[0035] In summary, the waterproof and compacting quick-setting agent, when used in shotcrete, can enhance the waterproofing effect of shotcrete, increase the density of shotcrete, improve the strength of shotcrete, and thus improve the durability of shotcrete. Therefore, when used in shotcrete, this quick-setting agent can fundamentally improve the current situation where shotcrete only provides initial support and cannot provide long-term support, and has broad application prospects in this field.

[0036] The preparation method of the above-mentioned waterproof dense type quick-setting agent comprises the following steps: Add water to the container, start high-speed dispersion, add suspending agent, stir for 0.5-1h, then add organic complex waterproofing agent, continue to disperse for 1-1.5h, add modified silica sol and coagulant, continue to disperse for 2-3h to obtain a waterproof and dense quick-setting agent.

[0037] The waterproof and dense quick-setting agent can be used to prepare shotcrete.

[0038] In order to better illustrate the technical effects of this embodiment, the following technical cases are used for illustration: Example 1: A waterproof and dense quick-setting agent, composed of the following components in parts by weight: 10 parts of modified suspending agent, 200 parts of modified silica sol, 100 parts of organic complex waterproofing agent, 500 parts of coagulant, and 190 parts of water.

[0039] The preparation method of the waterproof and dense quick-setting agent is as follows: add 190 parts of deionized water to a 1L three-necked flask, turn on high-speed dispersion, the speed is 1200r / min, first add 10 parts of modified suspending agent, stir for 0.5h, then add 100 parts of organic complex waterproofing agent, continue to disperse for 1h, then add 200 parts of modified silica sol and 500 parts of coagulant, continue to disperse for 2h, and obtain a waterproof quick-setting agent.

[0040] Among them, the preparation process of modified silica sol: 550 parts of purchased acidic silica sol (content 30%) were placed in a three-necked flask, heated to 40°C in a water bath, and then 200 parts of tridecafluorooctyltriethoxysilane and 250 parts of ethanol were added and reacted for 1 hour to obtain modified silica sol.

[0041] Among them, the preparation process of organic complex waterproofing agent is as follows: A. Add 250 parts of sodium hydroxide, 400 parts of aluminum hydroxide, and 350 parts of water into a three-necked flask and heat it in an oil bath to 110°C. React for 1.5 hours to obtain a sodium aluminate solution. Take 100 parts of the prepared sodium aluminate solution and add it into 500 parts of an aluminum sulfate solution with an aluminum oxide content of 7.5% to produce a large amount of precipitate. Filter the precipitate, wash it, and dry it under reduced pressure at low temperature to obtain amorphous aluminum hydroxide.

[0042] B. Slowly add 30 parts of amorphous aluminum hydroxide into 80 parts of organic acid complexing agent (erucic acid) and slowly stir for 3 hours to obtain an organic complexing waterproofing agent.

[0043] The preparation process of the coagulant is as follows: 200 parts of water, 130 parts of aluminum hydroxide, 280 parts of fluorosilicic acid (mass fraction 40%), and 300 parts of aluminum sulfate were added to a three-necked flask, heated to 80°C in a water bath, stirred and reacted for 2 hours, then 80 parts of the above sodium aluminate solution were added, stirred for 1 hour, and cooled to obtain a coagulant-accelerating component.

[0044] The preparation process of the modified suspending agent is as follows: In a three-part flask, 10 parts of silane coupling agent KH-550 were dissolved in a mixed solution of 20 parts of ethanol and water (ethanol to water mass ratio of 1:1), and 50 parts of suspending agent hydrated magnesium silicate were added. The suspending agent was surface modified at room temperature and stirred for 1 hour to obtain a modified suspending agent.

[0045] Example 2: This embodiment is based on embodiment 1, and differs from the embodiment in that: The modifier used in the modified acidic silica sol is n-octyltriethoxysilane; the organic acid complexing agent used in the preparation process of the organic complex waterproofing agent is oleic acid; Example 3: This embodiment is based on embodiment 1, and differs from the embodiment in that: The dosage of each component in the waterproof and dense quick-setting agent is different. Specifically, the dosage of the organic complex waterproofing agent is increased and the dosage of the modified silica sol is reduced. The preparation method of each component is the same as that of Example 1. Specifically: A waterproof and dense quick-setting agent, composed of the following components in parts by weight: 10 parts of modified suspending agent, 100 parts of modified silica sol, 200 parts of organic complex waterproofing agent, 500 parts of coagulant, and 190 parts of water.

[0046] The preparation method of the waterproof and dense quick-setting agent is as follows: add 190 parts of deionized water to a 1L three-necked flask, turn on high-speed dispersion, the speed is 1200r / min, first add 10 parts of modified suspending agent, stir for 0.5h, then add 200 parts of organic complex waterproofing agent, continue to disperse for 1h, then add 100 parts of modified silica sol and 500 parts of coagulant, continue to disperse for 2h to obtain a waterproof quick-setting agent.

[0047] Example 4: This embodiment is based on embodiment 1, and differs from the embodiment in that: The dosage of each component in the waterproof and dense quick-setting agent is different, specifically the dosage of the organic complex waterproofing agent is increased, and the preparation method of each component is the same as that of Example 1. Specifically: A waterproof and dense quick-setting agent, composed of the following components in parts by weight: 10 parts of modified suspending agent, 200 parts of modified silica sol, 200 parts of organic complex waterproofing agent, 500 parts of coagulant, and 190 parts of water.

[0048] The preparation method of the waterproof and dense quick-setting agent is as follows: add 190 parts of deionized water to a 1L three-necked flask, turn on high-speed dispersion, the speed is 1200r / min, first add 10 parts of modified suspending agent, stir for 0.5h, then add 200 parts of organic complex waterproofing agent, continue to disperse for 1h, then add 200 parts of modified silica sol and 500 parts of coagulant, continue to disperse for 2h, and obtain a waterproof quick-setting agent.

[0049] Example 5: This embodiment is based on embodiment 1, and differs from the embodiment in that: The dosage of each component in the waterproof and dense quick-setting agent is different. Specifically, the dosage of the organic complex waterproofing agent and the dosage of the modified silica sol are increased. The preparation method of each component is the same as that of Example 1. Specifically: A waterproof and dense quick-setting agent, composed of the following components in parts by weight: 10 parts of modified suspending agent, 250 parts of modified silica sol, 250 parts of organic complex waterproofing agent, 500 parts of coagulant, and 190 parts of water.

[0050] The preparation method of the waterproof and dense quick-setting agent is as follows: add 190 parts of deionized water to a 1L three-necked flask, turn on high-speed dispersion, the speed is 1200r / min, first add 10 parts of modified suspending agent, stir for 0.5h, then add 250 parts of organic complex waterproofing agent, continue to disperse for 1h, then add 250 parts of modified silica sol and 500 parts of coagulant, continue to disperse for 2h to obtain a waterproof quick-setting agent.

[0051] Comparative Example 1: This comparative example is based on Example 1, and differs from the example in that: The formula of waterproof and dense quick-setting agent does not contain modified silica sol, and the dosage of organic complex waterproofing agent and water is increased, as follows: A waterproof and dense quick-setting agent, composed of the following components in parts by weight: 10 parts of modified suspending agent, 200 parts of organic complex waterproofing agent, 500 parts of coagulant, and 290 parts of water.

[0052] The preparation method of the waterproof and dense quick-setting agent is as follows: add 290 parts of deionized water to a 1L three-necked flask, turn on high-speed dispersion, the speed is 1200r / min, first add 10 parts of modified suspending agent, stir for 0.5h, then add 200 parts of organic complex waterproofing agent, continue to disperse for 1h, then add 500 parts of coagulant, continue to disperse for 2h, and obtain a waterproof quick-setting agent.

[0053] Comparative Example 2: This comparative example is based on Example 1, and differs from the example in that: The formula of waterproof and dense quick-setting agent does not contain organic complex waterproofing agent, as follows: A waterproof and dense quick-setting agent, composed of the following components in parts by weight: 10 parts of modified suspending agent, 200 parts of modified silica sol, 500 parts of coagulant, and 290 parts of water.

[0054] The preparation method of the waterproof and dense quick-setting agent is as follows: add 290 parts of deionized water to a 1L three-necked flask, turn on high-speed dispersion, the speed is 1200r / min, first add 10 parts of modified suspending agent, stir for 0.5h, add 200 parts of modified silica sol, continue to disperse for 1h, then add 500 parts of coagulant, continue to disperse for 2h to obtain a waterproof quick-setting agent.

[0055] Comparative Example 3: This comparative example is based on Example 1, and differs from the example in that: Contains no modified silica sol and no organic complex waterproofing agent.

[0056] The preparation method of ordinary accelerating setting agent is as follows: add 490 parts of deionized water to a 1L three-necked flask, turn on high-speed dispersion, the speed is 1200r / min, first add 10 parts of modified suspending agent, disperse for 0.5h, continue to disperse for 1h, then add 500 parts of coagulant, continue to disperse for 2h to obtain blank accelerating setting agent.

[0057] Performance testing: 1. Setting time and compressive strength test The setting time and one-day compressive strength of the accelerating setting agent were tested in accordance with GB / T 35159-2017 Accelerating setting agents for shotcrete.

[0058] Benchmark cement (produced in July 2024), accelerator dosage 6%, setting time (00:00) test mix ratio is 400g cement, 140g water, and compressive strength (MPa) test mix ratio is 900g cement, 450g water, and 1350g standard sand. The test data of setting time and compressive strength are shown in Table 1: Table 1 From Table 1 we can see that: 1) From Comparative Examples 1 and 3, it can be seen that adding an organic complex waterproofing agent will reduce the strength of the mortar; 2) From Comparative Examples 2 and 3, it can be seen that adding modified silica sol can increase the strength of mortar, indicating that improving silica sol can increase the density of mortar test blocks; 3) From Example 1, Example 2 and Comparative Example 3, it can be seen that the combined use of the organic complex waterproofing agent and the modified silica sol can ensure that the mortar strength is higher than the benchmark; 4) Compared with Example 4, the mechanical properties of the mortar are improved after the modified silica sol is added.

[0059] 2. Water absorption test of mortar test block According to GB / T 35159-2017 "Accelerators for Shotcrete", mortar test blocks were formed and their 48-hour water absorption was measured. The specific operation method is as follows: 1) The mortar test blocks mixed with different waterproof, dense and quick-setting agents and ordinary quick-setting agents were cured under standard curing conditions for 28 days, then dried in an oven at 40°C to constant weight and placed at room temperature for 24 hours. At this time, the mass of each mortar test block was recorded and recorded as m0. 2) Place each mortar test block in parallel in a water bath, with the water surface covering the surface of the mortar test block by 3mm. After 48 hours, take it out and absorb the moisture on the surface of the test block with filter paper. Then measure its mass and record it as m1. 3) Calculate the 48-hour water absorption rate of the mortar test block according to the following formula: The results are shown in Table 2: Table 2 From Table 2 we can see that: 1) From Example 1, Example 2, and Comparative Example 3, it can be seen that the waterproofing effect of the system of tridecafluorooctyltriethoxysilane combined with erucic acid is better than that of n-octyltriethoxysilane; 2) From Examples 1 and 3, increasing the amount of the organic complex waterproofing agent component can further improve the waterproofing effect of the mortar test block, but the improvement effect is limited; 3) From Comparative Examples 1, 2, and 3, it can be seen that the use of modified silica sol and organic complex waterproofing agent alone has a certain waterproofing effect, but the effect of organic complex waterproofing agent is more obvious; 4) Compared with Example 3, Example 4 and Example 5 show that increasing the amount of the organic complex waterproof component and tridecafluorooctyl triethoxysilane can reduce the water absorption rate and increase the waterproof effect.

[0060] 3. Observation of waterproof effect inside mortar test block After testing the compressive strength of the mortar test block, distilled water was gently dripped on the fractured section of the mortar test block to observe the waterproof effect inside the mortar. The test pictures of the mortar test blocks prepared by adding the accelerators of Examples 1 to 5 and Comparative Examples 1 to 3 are shown as follows: Figures 1-8 shown.

[0061] Depend on Figures 1-8 It can be seen that: 1) Comparing Comparative Examples 1 and 2 with Comparative Example 3, the water droplets in Comparative Example 1 cannot spread out, indicating that the organic complex waterproofing agent forms a good waterproof structure inside the mortar. The water droplets in Comparative Example 2 spread to a certain extent, which is slightly better than Comparative Example 3 (blank), indicating that the modified silica sol only has a certain waterproof effect.

[0062] 2) From Examples 1 to 5, it can be seen that the modified silica sol is used in combination with the organic complex waterproof material, and the internal waterproofing of the mortar test block is still good.

[0063] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A waterproof and dense quick-setting agent, characterized in that: It comprises the following components in parts by weight: 5-10 parts of suspending agent, 50-250 parts of modified silica sol, 100-250 parts of organic complex waterproofing agent, 400-600 parts of coagulant, water; Wherein, the modified silica sol is obtained by modifying the acidic silica sol with a modifier, and the modifier is a silane coupling agent; Wherein, the organic complex waterproofing agent is a higher fatty acid aluminum complex.

2. A waterproof and dense quick-setting admixture according to claim 1, characterized in that: The preparation process of the modified silica sol is as follows: After 500-600 parts of the acidic silica sol with a content of 30% is heated to 40-45° C. in a water bath, 200-250 parts of the modifier and 150-200 parts of ethanol are added and reacted for 1-1.5 hours to obtain the modified silica sol.

3. A waterproof and dense quick-setting admixture according to claim 1, characterized in that: The silane coupling agent includes at least one of tridecafluorooctyltriethoxysilane and n-octyltriethoxysilane.

4. A waterproof and dense quick-setting admixture according to claim 1, characterized in that: The preparation process of the organic complex waterproofing agent is as follows: 20-30 parts of amorphous aluminum hydroxide are slowly added to 80-100 parts of an organic acid complexing agent and slowly stirred for 3-4 hours to obtain the organic complexing waterproofing agent, wherein the organic acid complexing agent includes at least one of oleic acid and erucic acid.

5. A waterproof and dense quick-setting admixture according to claim 1, characterized in that: The preparation process of the coagulant is as follows: 180-250 parts of water, 100-130 parts of aluminum hydroxide, 200-280 parts of 40% by mass silicofluoric acid, and 300-400 parts of aluminum sulfate are mixed, heated to 80-85° C. in a water bath, stirred and reacted for 2-3 hours, and then 50-80 parts of sodium metaaluminate solution are added, and stirring is continued for 1-1.5 hours. The mixture is cooled to obtain the coagulant.

6. A waterproof and dense quick-setting admixture according to claim 5, characterized in that: The preparation process of the sodium metaaluminate solution is as follows: 250 parts of sodium hydroxide, 400 parts of aluminum hydroxide and 350 parts of water were mixed, heated in an oil bath to 110-115° C., and reacted for 1.5-2 hours to obtain the sodium metaaluminate solution.

7. A waterproof and dense quick-setting admixture according to claim 1, characterized in that: The suspending agent is a modified suspending agent, which is obtained by modifying the suspending agent through silane coupling, and the suspending agent is hydrated magnesium silicate.

8. A waterproof and dense quick-setting admixture according to claim 7, characterized in that: The preparation process of the modified suspending agent is as follows: The silane coupling agent KH-550 is dissolved in an ethanol aqueous solution, and the solution is added into a suspending agent. The surface of the suspending agent is modified at room temperature and stirred for 1-1.5 hours to obtain the modified suspending agent.

9. The method for preparing a waterproof and dense quick-setting admixture according to any one of claims 1 to 8, wherein: The steps include: Add water to the container, start high-speed dispersion, add the suspending agent, stir for 0.5-1 hour, add the organic complex waterproofing agent, continue to disperse for 1-1.5 hours, add the modified silica sol and the coagulant, continue to disperse for 2-3 hours, and obtain the waterproof and dense quick-setting agent.

10. Use of the waterproof and dense quick-setting admixture according to any one of claims 1 to 8 in the preparation of shotcrete.

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