Highly impermeable hydraulic concrete for pump stations and method for its production

Abstract

The application relates to the field of concrete, in particular to high anti-permeability hydraulic concrete for a pump station and a preparation method thereof. The method comprises the following steps: uniformly mixing cement, fly ash, coarse and fine aggregates, nano silicon dioxide and an expansive agent to obtain a mixture, adding a water reducing agent, an air entraining agent, a crystalline waterproof agent and water, and stirring in a stirrer to uniformly mix to obtain a mixture of the high anti-permeability hydraulic concrete for the pump station. Compared with ordinary hydraulic concrete, the concrete of the application optimizes the compactness of an 'interface transition zone' through nano silicon dioxide, simultaneously compensates shrinkage through a composite expansive agent, prevents water permeation channels from being formed due to dry shrinkage cracking, and changes hydrophilic capillary pore walls into hydrophobicity through a crystalline waterproof agent to block water permeation from a physical and chemical perspective. A three-dimensional defense system is constructed through structure densification, volume densification and hydrophobicity, so that the anti-permeability of the pump station concrete is improved, cracking is reduced, and the service life of the structure can be prolonged.

Description

Technical Field

[0001] This invention relates to the field of concrete, and more particularly to a high impermeability concrete for pumping stations and its preparation method. Background Technology

[0002] Pumping stations are key structures in water conservancy projects. Their concrete structures must withstand the combined effects of high water pressure, groundwater level fluctuations, water erosion, and freeze-thaw cycles over long periods. Hydraulic concrete, as a material that is in constant contact with water, must simultaneously meet durability requirements such as impermeability, freeze-thaw resistance, and corrosion resistance. For pumping stations, the main structure (such as the pump house floor, pool walls, intake control well, and collection pool) is in direct contact with the water. Insufficient impermeability can lead to structural leakage, affecting normal operation, or even cause steel corrosion, accelerated concrete deterioration, and ultimately, jeopardize structural safety.

[0003] Currently, common anti-cracking measures include adding mineral admixtures such as fly ash and slag to reduce the heat of hydration, or adding fibers and expanding agents to improve crack resistance. However, while these methods can improve impermeability and freeze-thaw resistance to some extent, they are designed for general hydraulic concrete and do not fully consider the special impermeability requirements of pump station structures under long-term high water pressure and alternating wet and dry conditions. Therefore, developing a highly impermeable hydraulic concrete specifically designed for the environmental characteristics of pump station projects and possessing a systematic impermeability mechanism has significant engineering application value and practical significance.

[0004] The waterproof concrete disclosed in patent document CN121135302B is mainly prepared by adding materials such as silica fume, reinforcing materials, crystallization inducing agents, and repair agents, thereby improving the impermeability and self-healing properties of concrete materials. The impermeable concrete disclosed in CN121651820A mainly improves the impermeability of materials by adding materials such as water-based polyurethane, fiber materials, and silane coupling agent KH-550. When stress is generated due to concrete cracking, the inner supporting material plays a directional repair and filling role, improving the self-healing properties of concrete and effectively extending its service life. However, the shortcomings of the existing impermeable concrete preparation methods lie in the fact that they do not fully consider the special impermeability requirements of pump station structures under long-term high water pressure and alternating wet and dry environments. Summary of the Invention

[0005] In order to solve the technical problems existing in the prior art, the purpose of this invention is to provide a high impermeability hydraulic concrete for pumping stations and a method for preparing the same to solve the above-mentioned technical problems.

[0006] According to a first aspect of the present invention, the present invention provides a highly impermeable hydraulic concrete for pumping stations, comprising the following raw material components by weight: 300-340 parts of ordinary Portland cement; 70-90 parts fly ash; 710-740 parts fine aggregate; 540-570 parts of coarse aggregate; 440-480 parts of the second coarse aggregate; 2-5 parts of crystalline waterproofing agent; 25-45 parts of expanding agent; 2-8 parts of nano-silica; 2-6 parts water-reducing agent; 1-6 parts of air-entraining agent; 150-180 parts water.

[0007] In some embodiments, the strength grade of the ordinary silicate cement is not less than 42.5.

[0008] In some embodiments, the fly ash is Grade I fly ash or Grade II fly ash.

[0009] In some embodiments, the fineness modulus of the fine aggregate is 2.5-2.8.

[0010] In some embodiments, the particle size of the first coarse aggregate is 5-20 mm; In some embodiments, the particle size of the second coarse aggregate is 20-40 mm.

[0011] In some embodiments, the nano-silica has a particle size of 30-60 nm and a SiO2 content of not less than 99%.

[0012] In some embodiments, the crystalline waterproofing agent is WF-S3 crystalline waterproofing agent produced by Beijing Furuiles Technology Development Co., Ltd. In some embodiments, the expanding agent is FQY calcium sulfoaluminate-calcium oxide composite expanding agent produced by Wuhan Sanyuan Special Building Materials Co., Ltd. In some embodiments, the water-reducing agent is PC-1H polycarboxylate high-performance water-reducing agent (retarded setting type) produced by Shanxi Pengcheng Construction Technology Co., Ltd. In some embodiments, the air-entraining agent is PC-YQ air-entraining agent produced by Shanxi Pengcheng Construction Technology Co., Ltd.

[0013] This invention optimizes the density of the "interface transition zone" using nano-silica, while utilizing an expanding agent to compensate for shrinkage and prevent the formation of water seepage channels due to drying shrinkage cracking. A crystalline waterproofing agent transforms the hydrophilic capillary walls into hydrophobic ones, blocking water penetration from a physicochemical perspective. A three-dimensional defense system is constructed through structural density, volumetric density, and hydrophobicity.

[0014] This invention not only improves the impermeability of concrete, but also takes into account the impermeability requirements and durability of pump station structures under the coupled effects of "long-term immersion (high-pressure seepage) + wet-dry cycle (water level fluctuation)".

[0015] According to a second aspect of the present invention, the present invention provides a method for preparing highly impermeable hydraulic concrete for pumping stations, comprising the following steps: Cement, fly ash, coarse and fine aggregates, nano silica, and expansion agent are mixed (dry-mixed in a mixing pot for 60-90 seconds) to obtain a mixture. Then, water-reducing agent, air-entraining agent, crystalline waterproofing agent, and water are added and stirred in a mixer to obtain a uniform mixture for high impermeability concrete for pumping stations. The mixture is then poured to obtain the high impermeability concrete for pumping stations.

[0016] In some embodiments, in the preparation method of high impermeability hydraulic concrete for pumping stations, after obtaining the mixture of high impermeability hydraulic concrete for pumping stations, the slump and air content of the mixture are tested; when the slump of the mixture of high impermeability hydraulic concrete for pumping stations is 180mm~200mm and the air content is 3.5%~5%, the quality of the mixture of high impermeability hydraulic concrete for pumping stations is determined to be qualified, and then it is poured (transported to the pumping station construction site for pouring).

[0017] In some implementations, after pouring, a moisturizing curing process is carried out for no less than 14 days.

[0018] In some embodiments, the moisturizing maintenance includes covering the surface with a moisturizing film or a wet burlap sack after pouring.

[0019] In some embodiments, the moisturizing maintenance includes: covering the concrete with a moisturizing maintenance film or wet burlap sacks after pouring; adding shading facilities during high-temperature construction in summer; taking heat preservation measures during low-temperature construction in winter; and keeping the concrete surface moist during the curing period.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention employs a composite method of ordinary silicate cement and fly ash, combined with the use of nano-silica and crystalline waterproofing agents, which can effectively improve the impermeability of pump station operating environments, thereby extending the service life of the pump station. Experimental verification shows that, compared with ordinary hydraulic concrete, the concrete provided by this invention optimizes the density of the "interface transition zone" through nano-silica, while using a composite expansion agent to compensate for shrinkage, preventing the formation of seepage channels due to drying shrinkage cracking. The crystalline waterproofing agent transforms the hydrophilic capillary walls into hydrophobic ones, blocking water penetration from a physicochemical perspective. By constructing a three-dimensional defense system through structural density, volume density, and hydrophobicity, the impermeability of the pump station concrete is improved, cracking is reduced, and the structural lifespan is extended. Attached Figure Description

[0021] Figure 1 The graph shows the results of the impermeability of the concrete prepared for the comparative examples and embodiments. Detailed Implementation

[0022] To better understand the technical solution of the present invention, the embodiments of the present invention are described in detail below. It should be understood that the described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] The units for parts by weight (mass parts) in this application may be g or kg, or other units of measurement commonly used in the art. For example, the units for parts by weight (mass parts) below are kg.

[0024] The main material information used in the following embodiments is shown in Table 1 below.

[0025] Table 1 Example 1 A highly impermeable hydraulic concrete for pumping stations comprises the following raw material components by weight: 280 parts of ordinary Portland cement; 120 parts fly ash; 835 parts of fine aggregate; 494 parts of coarse aggregate; 490 parts of the second coarse aggregate; 4 parts of crystalline waterproofing agent; 30 parts of expanding agent; 5 parts of nano-silica; 3 parts water-reducing agent; 5 parts of air-entraining agent; 160 portions of water.

[0026] The strength grade of the ordinary silicate cement is P·O42.5.

[0027] The fly ash is Class I fly ash.

[0028] The fineness modulus of the fine aggregate is 2.6.

[0029] The particle size of the first coarse aggregate is 5-20 mm; The particle size of the second coarse aggregate is 20-40 mm.

[0030] The nano-silica has a particle size of 30-60 nm and a SiO2 content of not less than 99%.

[0031] The crystalline waterproofing agent is WF-S3 crystalline waterproofing agent produced by Beijing Furuiles Technology Development Co., Ltd. The expanding agent is FQY calcium sulfoaluminate-calcium oxide composite expanding agent produced by Wuhan Sanyuan Special Building Materials Co., Ltd. The water-reducing agent is PC-1H polycarboxylate high-performance water-reducing agent (retarded setting type) produced by Shanxi Pengcheng Construction Technology Co., Ltd. The air-entraining agent is PC-YQ air-entraining agent produced by Shanxi Pengcheng Construction Technology Co., Ltd.

[0032] This invention provides a method for preparing highly impermeable hydraulic concrete for pumping stations, comprising the following steps: Cement, fly ash, coarse and fine aggregates, nano silica, and expansion agent are mixed (dry mixing in a mixing pot for 90 seconds) to obtain a mixture. Then, water-reducing agent, air-entraining agent, crystalline waterproofing agent, and water are added, and the mixture is stirred in a mixer to obtain the high impermeability concrete mixture for pumping stations.

[0033] In the preparation method of high impermeability hydraulic concrete for pumping stations, after obtaining the mixture of high impermeability hydraulic concrete for pumping stations, the slump and air content of the mixture are tested (refer to SL / T 352-2020 "Test Procedure for Hydraulic Concrete"); when the slump of the mixture of high impermeability hydraulic concrete for pumping stations is 180mm~200mm and the air content is 3.5%~5.0%, the quality of the mixture of high impermeability hydraulic concrete for pumping stations is deemed qualified, and then it is poured (transported to the pumping station construction site for pouring).

[0034] After the pouring is completed, moisturizing and curing should be carried out for 14 days.

[0035] The moisturizing and maintenance includes covering the surface with a moisturizing and maintenance film or a wet burlap sack after pouring.

[0036] Example 2 This embodiment is basically the same as Embodiment 1, except that the amount of nano-silica doped is 3 parts.

[0037] Example 3 This embodiment is basically the same as Embodiment 1, except that the dosage of the crystalline waterproofing agent is 2 parts.

[0038] Example 4 This embodiment is basically the same as Embodiment 1, except that the amount of expanding agent is 25 parts.

[0039] Comparative Example 1 This comparative example is basically the same as Example 1, except that the amount of nano-silica doping is 0 parts.

[0040] Comparative Example 2 This comparative example is basically the same as Example 1, except that the amount of crystalline waterproofing agent is 0 parts.

[0041] Comparative Example 3 This comparative example is basically the same as Example 1, except that the amount of expanding agent is 0 parts.

[0042] Comparative Example 4 This comparative example is basically the same as Example 1, except that the amount of nano-silica is 0 parts and the amount of crystalline waterproofing agent is 0 parts.

[0043] Comparative Example 5 This comparative example is basically the same as Example 1, except that the amount of nano-silica is 0 parts and the amount of expansion agent is 0 parts.

[0044] Comparative Example 6 This comparative example is basically the same as Example 1, except that the dosage of the crystalline waterproofing agent is 0 parts and the dosage of the expanding agent is 0 parts.

[0045] Effect verification I. Water Resistance Test High impermeability concrete prepared in each embodiment and concrete prepared in each comparative example were taken as test samples, and then the impermeability performance was tested in accordance with SL / T 352-2020 "Test Procedure for Hydraulic Concrete".

[0046] II. Mechanical Strength Test High impermeability hydraulic concrete prepared in each embodiment and concrete prepared in each comparative example were taken as test samples, and mechanical properties (compressive strength) were tested in accordance with SL / T 352-2020 "Test Procedure for Hydraulic Concrete".

[0047] III. Micromechanical property testing The micromechanical properties were tested according to the methods described in the literature (Composition, Structural Design and Performance Study of Composite Cement Paste Based on Chloride Ion Attack Resistance). Specifically, high-permeability hydraulic concrete prepared in each example and concrete prepared in each comparative example were used as test samples. A nanoindentation lattice test method was then employed, and the micromechanical properties of the paste were tested using statistical methods. Areas without obvious defects or pores were randomly selected for 12... A 12-point lattice test was conducted, with indentation test points spaced 10 μm apart in both the direction perpendicular to and parallel to the interface. At least three lattice tests were performed in each region to ensure at least 400 valid data points were obtained for statistical analysis. In the nanoindentation test, the maximum load was set to 5 mN, the loading and unloading rates were both 5 mN / min, and the maximum load holding time was 5 s.

[0048] IV. Test Results The concrete properties are shown in Table 2 below. Figure 1 As shown.

[0049] Table 2 Table 2 shows that the impermeability grade of all four embodiments reached W10 or higher, while the impermeability grade of the six comparative examples was no higher than W8. This demonstrates that the impermeability performance of each embodiment is significantly better than that of the comparative examples, verifying the effectiveness of the described technical solution. In the four embodiments, the dosages of nano-silica, crystalline waterproofing agent, and expanding agent differed. Example 1 achieved a 28-day compressive strength of 47.1 MPa and an impermeability grade of W12, both higher than the other three embodiments. In summary, Example 1 is the optimal formulation.

[0050] The above descriptions are merely some embodiments of the present invention. Those skilled in the art can make various modifications and improvements without departing from the inventive concept of the present invention, and these all fall within the scope of protection of the present invention.

Claims

1. A type of highly impermeable hydraulic concrete for pumping stations, characterized in that, Based on parts by weight, it includes the following raw material components: 300-340 parts of ordinary Portland cement; 70-90 parts fly ash; 710-740 parts fine aggregate; 540-570 parts of coarse aggregate; 440-480 parts of the second coarse aggregate; 2-5 parts of crystalline waterproofing agent; 25-45 parts of expanding agent; 2-8 parts of nano-silica; 2-6 parts water-reducing agent; 1-6 parts of air-entraining agent; 150-180 parts water.

2. The high impermeability hydraulic concrete for pumping stations according to claim 1, characterized in that, The strength grade of the ordinary silicate cement shall not be less than 42.

5.

3. The high impermeability hydraulic concrete for pumping stations according to claim 1, characterized in that, The fly ash is either Grade I fly ash or Grade II fly ash.

4. The high impermeability hydraulic concrete for pumping stations according to claim 1, characterized in that, The fineness modulus of the fine aggregate is 2.5-2.

8.

5. The high impermeability hydraulic concrete for pumping stations according to claim 1, characterized in that, The first coarse aggregate has a particle size of 5-20 mm; the second coarse aggregate has a particle size of 20-40 mm.

6. The high impermeability hydraulic concrete for pumping stations according to claim 1, characterized in that, The nano-silica has a particle size of 30-60 nm and a SiO2 content of not less than 99%.

7. The high impermeability hydraulic concrete for pumping stations according to claim 1, characterized in that, The crystalline waterproofing agent is WF-S3 crystalline waterproofing agent produced by Beijing Furuiles Technology Development Co., Ltd.; the expanding agent is FQY calcium sulfoaluminate-calcium oxide composite expanding agent produced by Wuhan Sanyuan Special Building Materials Co., Ltd.; the water-reducing agent is PC-1H polycarboxylate high-performance water-reducing agent produced by Shanxi Pengcheng Construction Technology Co., Ltd.; and the air-entraining agent is PC-YQ air-entraining agent produced by Shanxi Pengcheng Construction Technology Co., Ltd.

8. The method for preparing high impermeability hydraulic concrete for pumping stations according to any one of claims 1-7, characterized in that, Includes the following steps: Cement, fly ash, coarse and fine aggregates, nano silica, and expansion agent are mixed to obtain a mixture. Then, water-reducing agent, air-entraining agent, crystalline waterproofing agent, and water are added and mixed evenly to obtain the mixture of the high impermeability concrete for pumping stations. The mixture is then poured to obtain the high impermeability concrete for pumping stations.

9. The method for preparing high-permeability hydraulic concrete for pumping stations according to claim 8, characterized in that, After obtaining the high-permeability hydraulic concrete mixture for the pumping station, the slump and air content of the mixture are tested. When the slump of the high-permeability hydraulic concrete mixture for the pumping station is 180mm~200mm and the air content is 3.5%~5%, the quality of the high-permeability hydraulic concrete mixture for the pumping station is deemed qualified, and then it is poured.

10. The method for preparing high-permeability hydraulic concrete for pumping stations according to claim 9, characterized in that, After the pouring is completed, moisturizing and curing should be carried out for no less than 14 days.

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