Impermeable wall concrete for water conservancy and hydropower engineering and preparation method

Abstract

The invention relates to diaphragm wall concrete for water conservancy and hydropower engineering and a preparation method, and the diaphragm wall concrete comprises water, a polyacrylate emulsion, a cementing material, a coarse aggregate, a fine aggregate, a water reducing agent, a defoaming agent, an air entraining agent, synthetic fibers and inevitable impurities. The mass ratio of the sum of the water and the polyacrylate emulsion to the binding material is 0.30-0.40, and the use amount of the coarse aggregate is 900-1100 kg / m < 3 >; the use amount of the fine aggregate is 600-850kg / m < 3 >, and the sand ratio is 40-46%; the doping amount of the polyacrylate emulsion is 5-20% of the mass of the cementing material; the mixing amount of the water reducing agent is 0.6%-1.2% of the mass of the cementing material; the mixing amount of the defoaming agent is 0.8%-1.5% of the mass of the cementing material; the mixing amount of the air entraining agent is 0.2 / 10000-0.5 / 10000 of the mass of the cementing material; the mixing amount of the synthetic fibers is 0.5%-2.0% of the total volume of the concrete for the diaphragm wall.

Description

Technical Field

[0001] The present application relates to the technical field of water conservancy and hydropower engineering, and in particular to an anti-seepage wall concrete for water conservancy and hydropower engineering and a preparation method thereof. Background Art

[0002] In the past decade, my country's investment in water conservancy and hydropower has continued to increase, and water conservancy and hydropower projects have maintained a high-speed development trend. However, with the expansion of water conservancy and hydropower construction to the west, the deep riverbed cover in the western region has gradually become a limitation of existing technical means, making it only possible to consider earth-rock dam types for dam construction on the cover. Especially with the changes in dam construction needs and the development of dam construction technology, the scale of construction has continued to increase, dams are getting higher and higher, anti-seepage is getting deeper and deeper, and the difficulty is increasing. In particular, once the anti-seepage treatment of the dam foundation of a 100-meter-high dam is unqualified, it will bring great pressure to the subsequent operation and maintenance management. Therefore, effective control of dam foundation seepage and seepage deformation is a prerequisite for ensuring the safety of high earth-rock dams on thick cover layers.

[0003] Combined with domestic and foreign engineering examples, concrete anti-seepage wall is currently the most effective anti-seepage means for dealing with deep covering layers. The commonly used technical solution for concrete anti-seepage wall in engineering is to add a certain amount of bentonite or clay to conventional concrete to obtain plastic concrete with low strength and low elastic modulus. With the development of engineering scale and technology, the actual application of concrete anti-seepage wall has far exceeded the scope of anti-seepage, and it is necessary to take into account engineering issues such as anti-scouring, reinforcement, load-bearing and underground interception. In particular, with the continuous increase in the scale of dam construction, the head or pressure borne by the anti-seepage wall is increasing, and the internal force of the wall is increasing. The traditional plastic concrete with low strength and low elastic modulus can no longer meet the requirements. Ordinary rigid concrete has a large elastic modulus and cannot be coordinated with the deformation of the foundation. It is easy to produce stress concentration and damage when bearing load. Summary of the invention

[0004] The first aspect of the present application provides an anti-seepage wall concrete for water conservancy and hydropower projects. The anti-seepage wall concrete has the characteristics of low early strength, high late strength, low elastic modulus, small elastic-strength ratio, large ultimate deformation, and high anti-seepage performance. In actual construction, the anti-cracking performance of the anti-seepage wall can be improved, thereby enhancing the safety of the anti-seepage wall and ensuring the quality of the project.

[0005] The anti-seepage wall concrete comprises water, polyacrylate emulsion, cementitious material, coarse aggregate, fine aggregate, water reducing agent, defoaming agent, air entraining agent, synthetic fiber and inevitable impurities; the mass ratio of the sum of the water and the polyacrylate emulsion to the cementitious material is 0.30-0.40, the amount of the coarse aggregate is 900-1100 kg / m 3 The amount of fine aggregate is 600-850 kg / m 3, the sand ratio is 40% to 46%; the dosage of the polyacrylate emulsion is 5% to 20% of the mass of the cementitious material; the dosage of the water reducer is 0.6% to 1.2% of the mass of the cementitious material; the dosage of the defoamer is 0.8% to 1.5% of the mass of the cementitious material; the dosage of the air entraining agent is 0.2 / 10,000 to 0.5 / 10,000 of the mass of the cementitious material; the dosage of the synthetic fiber is 0.5% to 2.0% of the total volume of the anti-seepage wall concrete.

[0006] In addition, the anti-seepage wall concrete provided by the present application may also have the following additional technical features:

[0007] In an optional solution, the cementitious material includes cement, silica fume and fly ash, and the total amount of the cementitious material is 450-500 kg / m 3 , the sand ratio is 40% to 46%; in the cementitious material, the content of the silicon powder is 3% to 5% of the mass of the cementitious material; the content of the fly ash is 50% to 60% of the mass of the cementitious material.

[0008] In an optional solution, the cement is low-heat or medium-heat silicate cement, the cement contains MgO, and the MgO content satisfies: 3.5%≤MgO≤5.0%; the silica powder is densified silica powder, and the fly ash is Class F I fly ash.

[0009] In an optional solution, the coarse aggregate includes a first coarse aggregate with a particle size of 5 to 20 mm and a second coarse aggregate with a particle size of 20 to 40 mm, and the ratio of the first coarse aggregate to the second coarse aggregate is 65%:35% to 75%:25%.

[0010] In an optional solution, the void ratio of the coarse aggregate is ≤43%; and the fineness modulus of the fine aggregate is 2.8-3.2.

[0011] In an optional scheme, the solid content of the polyacrylate emulsion is 40% to 60%, the water reducer is a slow-setting polycarboxylic acid high-performance water reducer, and the water reduction rate of the water reducer is not less than 30%; the defoamer is a silicone defoamer; and the air entraining agent is a foam-stabilizing air entraining agent.

[0012] In an optional solution, the synthetic fiber is at least one of high-strength and high-modulus short-cut polyvinyl alcohol (PVA) fiber, composite polyethylene (PE) fiber, and polypropylene (PP) fiber.

[0013] The second aspect of the present application provides a method for preparing an anti-seepage wall concrete for a water conservancy and hydropower project. The method for preparing an anti-seepage wall concrete is used to prepare the anti-seepage wall concrete in the embodiment of the first aspect. The method for preparing an anti-seepage wall concrete comprises the following steps:

[0014] 1) weighing water, polyacrylate emulsion, cementitious material, coarse aggregate, fine aggregate, water reducing agent, defoaming agent, air entraining agent and synthetic fiber according to a preset proportion, wherein the cementitious material includes cement, silica fume and fly ash;

[0015] 2) Weigh 2 / 3 of the weight of mixing water, add the water reducer, defoamer, and polyacrylate emulsion into the water and stir evenly to prepare a liquid for use; weigh 1 / 3 of the weight of mixing water, add the air entraining agent into the water and stir evenly to prepare a diluted air entraining agent for use;

[0016] 3) Add fine aggregate and coarse aggregate into a forced mixer and stir for 30 seconds; then pour cement, silica fume, fly ash and synthetic fiber into a mixing pot and stir for 90 to 120 seconds; then add the mixed liquid evenly in 30 seconds during the stirring process and continue stirring for 60 to 90 seconds; finally, add the diluted air entraining agent evenly in 30 seconds during the stirring process and continue stirring for 60 to 90 seconds to make anti-seepage wall concrete.

[0017] In an optional solution, after the cut-off wall concrete is made, the slump of the cut-off wall concrete is 160-220 mm, and the compressive strength of the cut-off wall concrete after 90 days of age is greater than 40 MPa and the elastic modulus is less than 25 Gpa.

[0018] The beneficial effects of this application are:

[0019] The anti-seepage wall concrete and preparation method in the present application increase the working performance of concrete by adding polyacrylate emulsion, and form a flexible mesh film structure in the concrete after hardening to improve the bonding form between the composite cementitious material system structure and the aggregate, and enhance the toughness and durability of the concrete under the condition of less impact on the compressive strength. At the same time, the elastic modulus of the polyacrylate emulsion is much lower than that of the composite cementitious material system, which greatly reduces the elastic modulus of the concrete. In addition, through the combined effect of the defoamer and the air entraining agent, the defoamer is used to eliminate the unstable large bubbles introduced by the stirring of the polyacrylate emulsion, and then a large number of tiny, independent and stable small bubbles are introduced through the air entraining agent, so that the air content of the concrete reaches 7%±1.0%. At the same time, combined with the material properties of the fiber, the elastic modulus of the concrete can be effectively reduced while the early shrinkage is greatly reduced, and the durability of the concrete is greatly improved.

[0020] It should be understood that the foregoing general description and the following detailed description are exemplary only and are not restrictive of the present application. DETAILED DESCRIPTION

[0021] In order to better understand the technical solution of the present application, the embodiments of the present application are described in detail.

[0022] It should be clear that the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0023] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0024] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0025] With the development of engineering scale and technology, the actual application of concrete anti-seepage walls has far exceeded the scope of anti-seepage, and it is necessary to take into account engineering issues such as anti-impact, reinforcement, load-bearing and underground interception. In particular, with the continuous increase in the scale of dam construction, the head or pressure on the anti-seepage wall is increasing, and the internal force of the wall is increasing. The traditional low-strength and low-elastic modulus plastic concrete can no longer meet the requirements. Ordinary rigid concrete has a large elastic modulus and cannot be coordinated with the deformation of the foundation. It is easy to produce stress concentration and damage when bearing load.

[0026] Taking the Xiaolangdi Hydropower Station in my country as an example, the concrete design strength of the right bank anti-seepage wall of the Xiaolangdi main dam is 35MPa, which is the highest concrete strength anti-seepage wall in my country so far. Ordinary concrete was used in the early stage of the project, but due to its high early strength (5d compressive strength is 30.7MPa, 23d compressive strength is 44.7MPa), it is very difficult to make the joint holes. The slow-setting high-strength concrete was used in the construction to alleviate the difficulties caused by the high strength of the wall concrete to drill the joints, and set a new record for the depth of the anti-seepage wall at that time (82m). Combined with the technical performance of the anti-seepage wall concrete with a depth of more than 100m that has been built or is under construction in my country in recent years, the dam anti-seepage wall concrete has a special strength development law. For the design of high dam deep wall, it is generally required that the compressive strength at 28d age is not more than 25MPa, the compressive strength at 90d age is not less than 40MPa, and the elastic modulus at 90d age is not more than 25GPa. High-strength and low-elastic concrete wall materials are typical concrete with low early strength, high late strength and low elastic modulus. The early strength of concrete increases slowly, and the growth rate of strength in the later stage is high, which is exactly the opposite of the strength development law of ordinary concrete. Especially as the country increases its investment in infrastructure and pays more attention to environmental protection, the application of machine-made sand and gravel is becoming more and more extensive. The use of machine-made sand and gravel to prepare concrete further increases the difficulty of reducing the elastic modulus of concrete. For this reason, the commonly used technical means is to reduce the elastic modulus as much as possible while ensuring the strength.

[0027] In this regard, the embodiments of the present application provide an anti-seepage wall concrete and a preparation method for water conservancy and hydropower projects. The produced anti-seepage wall concrete has the characteristics of low early strength, high later strength, low elastic modulus, small elastic-strength ratio, large ultimate deformation, and high anti-seepage performance. In actual construction, the anti-cracking performance of the anti-seepage wall can be improved, thereby greatly enhancing the safety of the anti-seepage wall and ensuring the quality of the project.

[0028] The first aspect of the present application provides an anti-seepage wall concrete for water conservancy and hydropower projects, the anti-seepage wall concrete comprising water, polyacrylate emulsion, cementitious material, coarse aggregate, fine aggregate, water reducer, defoamer, air entraining agent, synthetic fiber and inevitable impurities; the mass ratio of the sum of water and polyacrylate emulsion to cementitious material is 0.30-0.40, the amount of coarse aggregate is 900-1100 kg / m 3 ; The amount of fine aggregate is 600~850kg / m 3 , sand ratio is 40%~46%; the dosage of polyacrylate emulsion is 5%~20% of the mass of cementitious materials; the dosage of water reducer is 0.6%~1.2% of the mass of cementitious materials; the dosage of defoamer is 0.8%~1.5% of the mass of cementitious materials; the dosage of air entraining agent is 0.2 / 10,000~0.5 / 10,000 of the mass of cementitious materials; the dosage of synthetic fiber is 0.5%~2.0% of the total volume of anti-seepage wall concrete.

[0029] The anti-seepage wall concrete increases the working performance of the concrete by adding a certain proportion of polyacrylate emulsion, and forms a flexible mesh film structure in the concrete after hardening to improve the bonding form between the composite cementitious material system structure and the aggregate, and enhances the toughness and durability of the concrete under the condition of less impact on the compressive strength. At the same time, the elastic modulus of the polyacrylate emulsion is much lower than that of the composite cementitious material system, which greatly reduces the elastic modulus of the concrete. In addition, through the combined effect of the defoamer and the air entraining agent, the defoamer is used to eliminate the unstable large bubbles introduced by the stirring of the polyacrylate emulsion, and then a large number of tiny, independent and stable small bubbles are introduced through the air entraining agent, so that the air content of the concrete reaches 7%±1.0%. At the same time, combined with the material properties of the fiber, the elastic modulus of the concrete can be effectively reduced while the early shrinkage is greatly reduced, and the durability of the concrete is greatly improved.

[0030] In a specific embodiment, the cementitious material includes cement, silica fume and fly ash, and the total amount of the cementitious material is 450-500 kg / m 3 , the sand rate is 40%~46%; in the cementitious material, the content of silica powder is 3%~5% of the mass of the cementitious material; the content of fly ash is 50%~60% of the mass of the cementitious material.

[0031] This embodiment can significantly reduce the early strength of concrete by adding a large amount of high-quality Class I fly ash, and at the same time, the composite superposition effect of the fly ash + silica powder combination is used to fully stimulate the activity of the admixture. A large amount of SiO2 in the admixture participates in the secondary hydration of cement to ensure that the later strength has a large increase, so that the tensile strength and ultimate tensile value of the concrete are significantly improved, while the elastic modulus of the concrete remains basically unchanged or slightly reduced, further improving the crack resistance of the concrete. The anti-seepage wall concrete prepared by the material combination of high-magnesium low-heat or medium-heat silicate cement + silica powder + fly ash + polyacrylate emulsion + composite defoamer and air entraining agent + fiber has low early hydration heat and small drying shrinkage, and its 28d compressive strength is low, but the compressive strength after 28d age increases greatly, the compressive strength at 90d age can reach more than 40MPa, and the compressive elastic modulus at 90d age is less than 25GPa, and the durability is significantly improved, which is greatly superior to the anti-seepage wall concrete prepared by the prior art.

[0032] Specifically, the cement is P.LH42.5 low-heat Portland cement or P.MH42.5 medium-heat Portland cement whose performance meets the technical requirements of "Medium-heat Portland Cement, Low-heat Portland Cement" (GB / T200-2017), with an MgO content of 3.5%≤≤5.0%. High-magnesium low-heat or medium-heat cement with low initial hydration heat is used to offset the volume shrinkage of the anti-seepage wall concrete in the cooling stage, reduce early shrinkage, and increase the early adaptability of the anti-seepage wall concrete to the environment; a design age of 90d is used to make full use of the later strength of the low-heat or medium-heat Portland cement.

[0033] In addition, the silica fume is a densified silica fume that meets the technical requirements of the Technical Specifications for Silica Fume Added to Hydraulic Concrete (DL / T5777-2018). The addition of silica fume can significantly improve the cohesion of concrete, reduce bleeding and segregation, reduce the coarse pores in concrete, and improve the durability of concrete. In addition, the addition of silica fume increases the volume of concrete paste, which can further improve the deformation capacity of concrete, increase the later strength of concrete, and relatively reduce the elastic modulus.

[0034] The fly ash is Class F I fly ash that meets the technical requirements of the Technical Specifications for Fly Ash Used in Hydraulic Concrete (DL / T 5055-2007). By adding a large amount of high-quality Class I fly ash to concrete, the workability of concrete is increased, and the late secondary hydration time of fly ash is utilized to reduce the early strength of concrete while improving its long-term strength and impermeability, reducing the shrinkage of concrete, and not increasing the elastic modulus of concrete.

[0035] In a specific embodiment, the coarse aggregate is the engineering excavation material crushed by the aggregate production and processing system, and is divided into two specifications of 5-20mm and 20-40mm, and the ratio of the two specifications of coarse aggregate is 65%:35%-75%:25%. The performance of the coarse aggregate meets the relevant technical requirements of aggregate in the "Specification for Construction of Hydraulic Concrete" (DL / T 5144-2015), and has no potential alkali activity hazards, and the void ratio is ≤43%; the fine aggregate is the machine-made sand crushed by the aggregate production and processing system of the engineering excavation material, and the fineness modulus is 2.8-3.2. Its performance meets the relevant technical requirements of aggregate in the "Specification for Construction of Hydraulic Concrete" (DL / T 5144-2015), and has no potential alkali activity hazards.

[0036] In a specific embodiment, the solid content of the polyacrylate emulsion is 40% to 60%. The addition of the polyacrylate emulsion can wet and lubricate the artificial aggregate, make up for the shortcomings of the multi-angle and rough surface of the machine-made sand, overcome the adverse effects of the irregular shape of the machine-made sand, increase the fluidity, cohesion and water retention of the concrete, and at the same time, the elastic modulus of the polyacrylate emulsion is much lower than that of the composite cementitious material system, which greatly reduces the elastic modulus of the concrete.

[0037] The water reducer is a slow-setting polycarboxylic acid high-performance water reducer whose performance meets the technical requirements of "Concrete Admixtures" (GB 8076-2008), and the water reduction rate is not less than 30%; the slow-setting polycarboxylic acid high-performance water reducer with a high water reduction rate is used to reduce the unit water consumption of concrete, reduce the cement consumption, and reduce the elastic modulus of concrete.

[0038] The defoamer is an organosilicon defoamer whose performance meets the technical requirements of "Organosilicon Defoamer" (GB / T 26527-2011); the air entraining agent is a foam-stabilizing air entraining agent whose performance meets the technical requirements of "Concrete Admixture" (GB 8076-2008). The combination of organosilicon defoamer + foam-stabilizing air entraining agent eliminates the unstable large bubbles introduced by the stirring of polyacrylate emulsion, introduces a large number of tiny, independent and stable small bubbles, and makes the air content of concrete reach 7%±1.0%; the tiny, independent and stable small bubbles can significantly improve the workability of concrete mixture, and have excellent slump retention, effectively reduce the elastic modulus of concrete, and improve the durability of concrete.

[0039] In a specific embodiment, the synthetic fiber is a high-strength and high-modulus short-cut polyvinyl alcohol (PVA) fiber or one or more of a composite polyethylene (PE) fiber and a polypropylene (PP) fiber. By adding fibers with good adaptability to concrete, the problem of high air content causing large early shrinkage of the cut-off wall concrete is reduced, the formation of early shrinkage cracks is reduced, and the durability of the concrete is significantly improved.

[0040] The second aspect of the present application provides a method for preparing an anti-seepage wall concrete for a water conservancy and hydropower project. The method for preparing an anti-seepage wall concrete is used to prepare the anti-seepage wall concrete in the embodiment of the first aspect. The method for preparing an anti-seepage wall concrete comprises the following steps:

[0041] 1) Weigh water, polyacrylate emulsion, cementitious material, coarse aggregate, fine aggregate, water reducing agent, defoaming agent, air entraining agent and synthetic fiber according to a preset proportion, wherein the cementitious material includes cement, silica fume and fly ash;

[0042] 2) Weigh 2 / 3 of the weight of mixing water, add the water reducer, defoamer, and polyacrylate emulsion into the water and stir evenly to prepare a liquid for use; weigh 1 / 3 of the weight of mixing water, add the air entraining agent into the water and stir evenly to prepare a diluted air entraining agent for use;

[0043] 3) Add fine aggregate and coarse aggregate into a forced mixer and stir for 30 seconds; then pour cement, silica fume, fly ash and synthetic fiber into a mixing pot and stir for 90 to 120 seconds; then add the mixed liquid agent evenly dispersed in 30 seconds during the stirring process, and continue stirring for 60 to 90 seconds; finally, add the diluted air entraining agent evenly dispersed in 30 seconds during the stirring process, and continue stirring for 60 to 90 seconds to make anti-seepage wall concrete. Pour the mixed concrete into the mold for molding, and demould after curing at 20 to 25°C for not less than 24 hours, and then standard curing for 90 days.

[0044] The anti-seepage wall concrete prepared by this method has a slump of 160-220 mm and a 28d compressive strength of less than 25 MPa. However, the strength increases significantly after 28 days, and the strength at 90 days can reach more than 40 MPa. However, its elastic modulus is less than 25 GPa. It can be used in actual construction to improve the crack resistance of the anti-seepage wall, which plays an important role in improving the safety of the project.

[0045] The technical solution of the present application will be further described below in conjunction with more specific embodiments:

[0046] A hydropower station reservoir adopts an asphalt concrete core rockfill dam with a maximum dam height of more than 100m. The dam body cover adopts a fully enclosed concrete anti-seepage wall for anti-seepage. The anti-seepage wall is 1.2m thick and has a maximum depth of about 120m. The physical properties of the anti-seepage wall concrete construction include: the slump of the concrete mixture is 18-22cm, the diffusion is 35-50cm, the slump is kept above 150mm for not less than 1h, the compressive strength at 28d age is ≤25MPa, the compressive strength at 90d age is ≥40MPa, the elastic modulus is not more than 25GPa, the anti-seepage grade is ≥W10, and the frost resistance grade is ≥F100.

[0047] The raw materials are as follows: cement is low-heat silicate cement with MgO content of 4.02%; coarse aggregate is crushed limestone excavated from the project, composed of 5-20mm small stones and 20-40mm medium stones, and has no potential alkali activity hazards; fine aggregate is crushed limestone excavated from the project, with a fineness modulus of 2.8, belonging to zone II medium sand, and has no potential alkali activity hazards; the solid content of polyacrylate emulsion is 43%; silica fume is densified silica fume; fly ash is Class F Class I fly ash; water reducer is slow-setting polycarboxylic acid high-performance water reducer with a water reduction rate of 32%; defoamer is an organosilicon defoamer; air entraining agent is a foam-stabilizing air entraining agent; fiber is PVA fiber; water is tap water. All raw materials meet the relevant specifications of hydropower engineering.

[0048] A concrete mix ratio test was conducted in combination with the concrete design index of the engineering dam anti-seepage wall. For comparison, Examples 1 to 2 and Comparative Examples 1 to 2 are provided below.

[0049] Example 1, the dam anti-seepage wall concrete is composed of the following components:

[0050]

[0051] Among them, Example 1 and Example 2 are two preferred embodiments of the present application.

[0052] Comparative Example 1 is a concrete mix ratio for an anti-seepage wall under the prior art route. The difference between Comparative Example 1 and the embodiment is that all low-heat silicate cement is replaced by ordinary silicate cement, and no polypropylene emulsion, silica powder, defoaming agent, or PVA fiber is added. The remaining parameters are slightly adjusted according to the fresh performance of the concrete.

[0053] Comparative Example 2 is an anti-seepage wall concrete prepared with low-heat silicate cement under the existing technical route. The difference between Comparative Example 2 and Comparative Example 1 is that all ordinary silicate cement is replaced by low-heat silicate cement, and the remaining parameters are slightly adjusted according to the fresh performance of concrete.

[0054] Concrete mixing performance, mechanical properties and durability performance tests are carried out in accordance with the "Test Procedures for Hydraulic Concrete" (DL / T 5150-2017).

[0055]

[0056] It can be seen from the test results of Example 1 and Example 2 that the cut-off wall concrete prepared in the two preferred schemes of the present invention can meet the design requirements and have a high safety margin.

[0057] It can be seen from the test results of Examples 1 and 2 and Comparative Example 1 that the anti-seepage wall concrete prepared by the present invention has slightly better fluidity, significantly reduced 28d compressive strength, slightly higher 90d compressive strength, significantly reduced 90d elastic modulus, significantly increased 90d axial tensile strength and 90d ultimate tensile value, and significantly improved 90d impermeability grade and 90d frost resistance grade, compared with the anti-seepage wall concrete prepared by the prior art solution using "ordinary Portland cement + 30% fly ash content" as the core.

[0058] It can be seen from the test results of Examples 1 and 2 and Comparative Example 2 that the anti-seepage wall concrete prepared by the present invention has slightly better fluidity, slightly lower 28d compressive strength, slightly higher 90d compressive strength, significantly lower 90d elastic modulus, significantly increased 90d axial tensile strength and 90d ultimate tensile value, and greatly improved 90d impermeability grade and 90d frost resistance grade.

[0059] It can be seen from the test results of Comparative Examples 1 and 2 that when the existing technical solution is used to prepare anti-seepage wall concrete with 90d compressive strength that meets the design requirements, the 28d compressive strength and 90d elastic modulus do not meet the design requirements. Among them, the 28d compressive strength and 90d elastic modulus of the concrete prepared with low-heat silicate cement are lower than those of ordinary silicate cement.

[0060] The above are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An anti-seepage wall concrete for water conservancy and hydropower projects, characterized in that: The anti-seepage wall concrete comprises water, polyacrylate emulsion, cementitious material, coarse aggregate, fine aggregate, water reducing agent, defoaming agent, air entraining agent, synthetic fiber and inevitable impurities; the mass ratio of the sum of the water and the polyacrylate emulsion to the cementitious material is 0.30-0.40, the amount of the coarse aggregate is 900-1100 kg / m 3 The amount of fine aggregate is 600-850 kg / m 3 , the sand ratio is 40% to 46%; the dosage of the polyacrylate emulsion is 5% to 20% of the mass of the cementitious material; the dosage of the water reducer is 0.6% to 1.2% of the mass of the cementitious material; the dosage of the defoamer is 0.8% to 1.5% of the mass of the cementitious material; the dosage of the air entraining agent is 0.2 / 10,000 to 0.5 / 10,000 of the mass of the cementitious material; the dosage of the synthetic fiber is 0.5% to 2.0% of the total volume of the anti-seepage wall concrete.

2. The anti-seepage wall concrete for water conservancy and hydropower engineering according to claim 1, characterized in that: The cementitious material includes cement, silica fume and fly ash, and the total amount of the cementitious material is 450-500 kg / m 3 , the sand ratio is 40% to 46%; in the cementitious material, the content of the silicon powder is 3% to 5% of the mass of the cementitious material; the content of the fly ash is 50% to 60% of the mass of the cementitious material.

3. The anti-seepage wall concrete for water conservancy and hydropower engineering according to claim 2, characterized in that: The cement is low-heat or medium-heat silicate cement, the cement contains MgO, and the content of MgO satisfies: 3.5%≤MgO≤5.0%; the silica powder is densified silica powder, and the fly ash is F Class I fly ash.

4. The anti-seepage wall concrete for water conservancy and hydropower engineering according to any one of claims 1 to 3, characterized in that: The coarse aggregate includes a first coarse aggregate with a particle size of 5 to 20 mm and a second coarse aggregate with a particle size of 20 to 40 mm, and the ratio of the first coarse aggregate to the second coarse aggregate is 65%:35% to 75%:25%.

5. The anti-seepage wall concrete for water conservancy and hydropower engineering according to claim 4, characterized in that: The void ratio of the coarse aggregate is ≤43%; the fineness modulus of the fine aggregate is 2.8-3.

2.

6. The anti-seepage wall concrete for water conservancy and hydropower engineering according to any one of claims 1 to 3 or 5, characterized in that: The solid content of the polyacrylate emulsion is 40% to 60%, the water reducer is a slow-setting polycarboxylic acid high-performance water reducer, and the water reduction rate of the water reducer is not less than 30%; the defoamer is an organosilicon defoamer; and the air entraining agent is a foam-stabilizing air entraining agent.

7. The anti-seepage wall concrete for water conservancy and hydropower engineering according to any one of claims 1 to 3 or 5, characterized in that: The synthetic fiber is at least one of high-strength and high-modulus short-cut polyvinyl alcohol (PVA) fiber, composite polyethylene (PE) fiber, and polypropylene (PP) fiber.

8. A method for preparing an anti-seepage wall concrete for water conservancy and hydropower engineering, used for preparing the anti-seepage wall concrete according to any one of claims 1 to 7, characterized in that: The method for preparing the anti-seepage wall concrete comprises the following steps: 1) weighing water, polyacrylate emulsion, cementitious material, coarse aggregate, fine aggregate, water reducing agent, defoaming agent, air entraining agent and synthetic fiber according to a preset proportion, wherein the cementitious material includes cement, silica fume and fly ash; 2) Weigh 2 / 3 of the weight of mixing water, add the water reducer, defoamer, and polyacrylate emulsion into the water and stir evenly to prepare a liquid for use; weigh 1 / 3 of the weight of mixing water, add the air entraining agent into the water and stir evenly to prepare a diluted air entraining agent for use; 3) Add fine aggregate and coarse aggregate into a forced mixer and stir for 30 seconds; then pour cement, silica fume, fly ash and synthetic fiber into a mixing pot and stir for 90 to 120 seconds; then add the mixed liquid evenly in 30 seconds during the stirring process and continue stirring for 60 to 90 seconds; finally, add the diluted air entraining agent evenly in 30 seconds during the stirring process and continue stirring for 60 to 90 seconds to make anti-seepage wall concrete.

9. The method for preparing anti-seepage wall concrete for water conservancy and hydropower engineering according to claim 8, characterized in that: After the cut-off wall concrete is manufactured, the slump of the cut-off wall concrete is 160-220 mm, and the compressive strength of the cut-off wall concrete after 90 days of age is greater than 40 MPa and the elastic modulus is less than 25 Gpa.

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