Long-distance pumping concrete for wet spraying as well as preparation method and application of long-distance pumping concrete
By adjusting the proportion of concrete raw materials and admixture composition, a wet spray long-distance pumped concrete with good pumpability and retarding performance was prepared, which solved the problem of rapid slump loss, separation and pipe blockage in long-distance pumping of existing concrete, and achieved improvement in construction efficiency and stability of project quality.
Patent Information
- Application Number
- CN202510231416.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-28
- Publication Date
- 2025-06-24
AI Technical Summary
During long-distance pumping, existing concrete is prone to problems such as rapid slump loss, separation, and pipe blockage, resulting in low construction efficiency, high cost and hidden dangers in project quality.
By adjusting the proportion of concrete raw materials and admixture ingredients, a wet spray long-distance pumped concrete with good pumpability and retarding performance is prepared. The concrete consists of cement, sand, gravel, admixture and water. The admixture is composed of water reducer, retarder, slump retainer and gas induction agent, and the mass ratio is 5.5-6.5:2.5-3.5:0.5-1:0-0.5.
The concrete can still maintain good wet spray performance after long-distance pumping, with low rebound rate, reduced risk of pipe blocking, improved construction efficiency, and stable project quality.
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Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of concrete, and particularly relates to a long-distance pumped concrete for wet spraying, a preparation method thereof, and an application thereof. Background Art
[0002] With the continuous expansion of the construction scale of mine engineering, tunnel engineering, etc., the wet spraying concrete support technology is increasingly widely used therein, which is of great significance for ensuring the structural stability and safety. In many complex construction environments, such as underground roadway development, ultra-long tunnel construction, etc., there are problems with difficult concrete transportation, which pose extremely high requirements for the pumping distance of concrete.
[0003] During the long-distance pumping process of traditional concrete, problems such as excessive slump loss, segregation, pipe blockage, etc. often occur. This not only seriously affects the construction efficiency, increases the construction cost, but also may lead to potential quality hazards in the project. Especially during wet spraying operations, the concrete needs to maintain good sprayability and performance stability after being pumped over a long distance under high pressure. Most of the existing concrete materials and their preparation methods on the market are difficult to meet the special requirements of such long-distance pumped wet spraying construction. Therefore, there is an urgent need to develop a long-distance pumped concrete for wet spraying to adapt to such construction scenarios. Summary of the Invention
[0004] In order to solve the problems that existing concrete often faces problems such as excessive slump loss, segregation, pipe blockage, etc. during long-distance pumping, cannot maintain good sprayability and performance stability, affect the construction efficiency, increase the construction cost, and may also lead to potential quality hazards in the project, the present invention provides a long-distance pumped concrete for wet spraying, a preparation method thereof, and an application thereof. By adjusting the proportion of concrete raw materials and the composition of admixtures, the prepared concrete has good pumpability, is not easy to block pipes, meets the requirement of still having good wet spraying performance after long-distance pumping of 1000 m and above, and has a low rebound rate.
[0005] In order to achieve the above object, the technical solution of the present invention is:
[0006] A long-distance pumped concrete for wet spraying is made from the following raw materials in parts by weight: 465 - 505 parts of cement, 825 - 875 parts of sand, 825 - 875 parts of gravel, 5 - 8 parts of admixture, and 175 - 215 parts of water; the admixture is made from the following raw materials: water reducer, retarder, slump retention agent, air-entraining agent, and the mass ratio of the water reducer, retarder, slump retention agent, air-entraining agent is: 5.5 - 6.5: 2.5 - 3.5: 0.5 - 1: 0 - 0.5. The sand and gravel can be premixed evenly in advance to reduce the time for on-site concrete preparation.
[0007] Preferably, the mass ratio of the water reducing agent, retarder, collapse retaining agent and air entraining agent in the admixture is 6:3:0.75:0.25.
[0008] Preferably, the cement is silicate cement, and the water reducer is a polycarboxylate water reducer or a naphthalene-based water reducer.
[0009] Preferably, the sand has a mud content of less than or equal to 3% and a mud block content of less than or equal to 1%.
[0010] Preferably, the stone particle size is less than or equal to 15 mm.
[0011] A method for preparing long-distance pumping concrete for wet spraying comprises the following steps:
[0012] Step 1, mixing sand and gravel in proportion and stirring evenly to obtain a sand and gravel mixture;
[0013] Step 2: Start the mixer and add sand and gravel mixture, cement, water and admixture into the mixer in proportion;
[0014] Step 3: After the raw materials are added, stir them thoroughly in a blender for 4 minutes to complete the preparation.
[0015] An application of long-distance pumping concrete for wet spraying, comprising the following steps:
[0016] Step 1: first pump water to the pipeline inlet, insert the seal after the water completely enters the pipeline, and then pump cement slurry, and the seal is transported toward the pipeline outlet along with the water and cement slurry;
[0017] Step 2: After the cement slurry has completely entered the pipeline, start pumping concrete;
[0018] Water, seals, cement slurry, and concrete will flow out from the pipe outlet in sequence. When concrete flows out of the pipe outlet, immediately connect the concrete spraying hose to the pipe outlet, mix high-pressure air and liquid quick-setting agent at the nozzle to spray the concrete for wet spraying support work;
[0019] Step 3: After the concrete wet spraying work is completed, start pumping cement slurry at the pipe inlet. When the cement slurry has completely entered the pipe, plug in the seal and then pump water.
[0020] Preferably, the sealing element is a sponge ball.
[0021] Preferably, the water-to-cement ratio of the cement slurry in step 1 is 0.6:1.
[0022] Preferably, the water-to-cement ratio of the cement slurry in step 3 is 0.5:1.
[0023] Through the above technical solution, the beneficial effects of the present invention are:
[0024] 1. The concrete mixture of the present invention has the advantages of good fluidity, small slump loss, and good anti-segregation performance. When performing long-distance concrete pumping, it can reduce the risk of pipe blockage, has good pumpability, and has good retarding performance. After long-distance pumping, it can still achieve good wet spraying effect and has a small rebound rate.
[0025] 2. The present invention provides a method for preparing concrete for wet spraying. By adopting the way of prefabricating sand and gravel mixture in advance, the preparation of sand and gravel mixture can be carried out during the idle time periods of non-concrete preparation and pumping, including procurement stage, transportation stage and other non-slurry-making stages, which improves the concrete preparation efficiency, shortens the mixing time, and makes the mixing of various concrete materials more uniform.
[0026] 3. The concrete prepared by the preparation method of the present invention has good fluidity, can maintain plasticity for a long time, and its good workability can avoid segregation and bleeding under the working conditions of high-pressure concrete transportation, improve the pumping performance, and make its pumping distance reach more than 1000m.
[0027] 4. The present invention also provides a long-distance pumping method for concrete for wet spraying, which can meet the requirement of carrying out concrete wet spraying after pumping the concrete for 1000m or even farther. By adjusting the appropriate water-binder ratio, the lubrication effect of the pipeline before pumping concrete is ensured. And after pumping the concrete, a relatively thick cement slurry is adopted to adapt to the higher pumping pressure, avoid the water passing through the cement slurry to the concrete section partially, and reduce the risk of pipe blockage in the long-distance pumping of concrete. Specific Embodiments
[0028] The present invention will be further described below in conjunction with specific embodiments:
[0029] This embodiment provides a long-distance pumped concrete for wet spraying, which is made of the following raw materials in parts by weight: 465 - 505 parts of cement, 825 - 875 parts of sand, 825 - 875 parts of stones, 5 - 8 parts of admixture, and 175 - 215 parts of water.
[0030] The above raw materials are all commercially available products: among them, the cement is ordinary Portland cement, which complies with the provisions of "Code for Acceptance of Construction Quality of Concrete Structures" GB50204 - 2002; the sand is fine sand, the mud content of the sand is less than or equal to 3% and the mud lump content is less than or equal to 1%; the particle size of the stones is less than or equal to 15mm, that is, the sundries and large particles of stones with a particle size greater than 15mm are removed, and the stones with a larger particle size should be crushed before use, and the organic matter content is less than or equal to 5%, and the mixing water complies with the provisions of "Standard for Concrete Water" JGJ63 - 2006.
[0031] As an implementable way, the stones can also be coal gangue, and the cement can also be slag Portland cement.
[0032] The admixture is made of the following raw materials: a water reducer, a retarder, a slump retaining agent, and an air entraining agent. The mass ratio of the water reducer, the retarder, the slump retaining agent, and the air entraining agent is 5.5-6.5: 2.5-3.5: 0.5-1: 0-0.5. The admixture is in accordance with the CJ / T486-2015 admixture standard.
[0033] The water reducer is a polycarboxylate water reducer or a naphthalene water reducer, wherein the main component of the polycarboxylate water reducer is methacrylic acid, which can disperse cement particles, improve the workability of the concrete mixture, reduce the unit water consumption and improve the fluidity of the concrete mixture while maintaining the slump of the concrete basically unchanged;
[0034] The main component of the retarder is sodium gluconate, which can reduce the hydration rate and hydration heat of cement or gypsum, prolong the setting time, and enable the freshly mixed concrete to maintain plasticity for a long time. It can significantly slow down the setting time of concrete, so that the concrete can be pumpable even if it does not solidify for 6 hours in the pipeline.
[0035] The main component of the collapse-preventing agent is phosphate, which can effectively improve the workability of concrete and prevent concrete from segregating and bleeding. It has good lubrication performance during transportation, especially in high-pressure concrete transportation conditions, to improve pumping performance;
[0036] The main component of air-entraining agent is sodium sulfate of fatty alcohol, which can introduce many evenly distributed, stable and closed fine bubbles into the concrete mixture, reduce the friction between cement particles, and improve the fluidity, cohesion and water retention properties of the concrete mixture.
[0037] The concrete mixture prepared by the above ratio has the advantages of good fluidity, small slump loss, and good anti-segregation performance. It can reduce the risk of pipe blockage during long-distance concrete pumping and has good pumpability. It also has good retarding performance. If pipe blockage occurs during long-distance pumping, it can prevent large-scale solidification of concrete in the pipeline due to untimely treatment, which will affect the progress of the project. In addition, the concrete mixture uses less water and can still react well with the liquid accelerating agent after long-distance pumping. It still has good adhesion when used for wet spraying, has a small rebound rate, and a fast accelerating time.
[0038] Example 1
[0039] The concrete of this embodiment is made of the following raw materials in parts by weight: 485 parts of cement, 850 parts of sand, 850 parts of gravel, 6.5 parts of admixture and 195 parts of water.
[0040] Among them, the mass ratio of polycarboxylic acid water reducer, retarder, collapse retaining agent and air entraining agent in the admixture is 6:3:0.75:0.25.
[0041] Example 2
[0042] The concrete of this embodiment is made from the following raw materials by weight: 465 parts of cement, 875 parts of sand, 825 parts of gravel, 8 parts of admixture, and 175 parts of water.
[0043] Among them, the mass ratio of polycarboxylate superplasticizer, retarder, slump retainer, and air-entraining agent in the admixture is 6:3:0.75:0.25.
[0044] Example 3
[0045] The concrete of this embodiment is made from the following raw materials by weight: 505 parts of cement, 825 parts of sand, 875 parts of gravel, 5 parts of admixture, and 215 parts of water.
[0046] Among them, the mass ratio of polycarboxylate superplasticizer, retarder, slump retainer, and air-entraining agent in the admixture is 6:3:0.75:0.25.
[0047] Example 4
[0048] The concrete of this embodiment is made from the following raw materials by weight: 485 parts of cement, 850 parts of sand, 850 parts of gravel, 6.5 parts of admixture, and 195 parts of water.
[0049] Among them, the mass ratio of polycarboxylate superplasticizer, retarder, slump retainer, and air-entraining agent in the admixture is 5.5:3.5:0.75:0.25.
[0050] Example 5
[0051] The concrete of this embodiment is made from the following raw materials by weight: 485 parts of cement, 850 parts of sand, 850 parts of gravel, 6.5 parts of admixture, and 195 parts of water.
[0052] Among them, the mass ratio of polycarboxylate superplasticizer, retarder, slump retainer, and air-entraining agent in the admixture is 6.5:2.5:0.75:0.25.
[0053] Comparative Example 1
[0054] This comparative example is basically the same as Example 1, except that no admixture is added.
[0055] Comparative Example 2
[0056] This comparative example is basically the same as Example 1, except that no polycarboxylate superplasticizer is added.
[0057] Comparative Example 3
[0058] This comparative example is basically the same as Example 1, except that no retarder is added.
[0059] The summary results of the concrete preparation component data of the above Examples 1-5 and Comparative Examples 1-3 are shown in Table 1 below.
[0060] Table 1 Summary of the distribution ratio of each concrete group
[0061]
[0062] The above-mentioned method for preparing long-distance pumped concrete for wet spraying, that is, the concrete preparation method corresponding to the above-mentioned embodiments 1-5 and comparative examples 1-3, comprises the following steps:
[0063] Step 1, mixing sand and gravel in proportion and stirring evenly to obtain a sand and gravel mixture;
[0064] The step 1 is carried out at a non-concrete preparation stage, that is, at a procurement stage, a transportation stage, etc., which can effectively reduce the mixing time during on-site concrete preparation, improve the mixing uniformity of each component, improve efficiency, and avoid affecting the continuity of concrete preparation and pumping.
[0065] Step 2: Start the mixer and add sand and gravel mixture, cement, water and admixture into the mixer in proportion;
[0066] Step 3: After the raw materials are added, stir them thoroughly in a blender for 4 minutes to complete the preparation.
[0067] The concrete made of different proportions of Examples 1-5 and Comparative Examples 1-3 was subjected to performance testing, 1000 m long-distance pumping and wet spraying tests (wherein the slump and initial setting time were tested in accordance with GB / T 50080-2016 "Standard for Performance Test Methods of Ordinary Concrete Mixtures"), and the results are shown in Table 2 below.
[0068] Table 2 Performance test results
[0069]
[0070] From the above test results, it can be obtained that the loss of initial slump-outlet slump is small, which reflects that the concrete prepared according to the embodiment ratio has a small loss over time (the greater the loss over time, the more difficult it is to pump, especially after long-distance transportation, which will cause concrete failure); the initial setting time is long, which reflects that the concrete prepared according to the embodiment ratio has good retarding performance and is suitable for long-distance pumping; the wet spraying rebound rate of the concrete prepared according to the embodiment ratio is small; the high-pressure water bleeding rate is small, which reflects that the concrete prepared according to the embodiment ratio has good water retention and good fluidity, and is not prone to segregation and blockage.
[0071] The workability (referring to the comprehensive performance of properties such as the fluidity, cohesiveness, and water retention of concrete) of the long-distance pumped concrete for wet spraying prepared according to the proportions of the examples is good, the loss over time is small, it has good setting retardation performance, is suitable for long-distance pumping, has a small risk of pipe blockage, and the wet spraying rebound rate is small after pumping for 1000 m, indicating good compatibility with the accelerating admixture and is suitable for concrete wet spraying.
[0072] From the test results of Comparative Examples 1-3, it can be seen that in Comparative Example 1, no admixture is added, and the workability and fluidity of the prepared concrete are poor compared with Example 1, and the setting retardation time is short; in Comparative Example 2, no water reducer is added, and the workability and fluidity of the prepared concrete are poor compared with Example 1; in Comparative Example 3, no setting retarder is added, and the setting speed of the prepared concrete is fast compared with Example 1; all are not suitable for long-distance concrete pumping.
[0073] The application of the long-distance pumped concrete for wet spraying described above, specifically, a long-distance concrete pumping method of 1000 m or more (in this example, a long-distance concrete pumping of 1000 m is taken as an example), includes the following steps:
[0074] First, use high-pressure pipelines with a length of 4 m each to connect and complete the 1000 m concrete pumping pipeline, ensuring good connection and good sealing between each pipeline.
[0075] Step 1: First, pump water into the pipeline inlet. After the water completely enters the pipeline, insert a sealing element, and then pump cement slurry. The sealing element is transported towards the pipeline outlet along with the water and cement slurry to complete the lubrication of the pipeline.
[0076] The sealing element is a sponge ball.
[0077] In Step 1, the water-cement ratio of the cement slurry is 0.6:1, and the cement slurry is prepared on-site.
[0078] When performing 1000 m long-distance pumping of concrete, first pump more than 1 m 3 of water. Subsequently, insert multiple sponge balls as sealing elements, try to avoid contact between the cement slurry and water, use 500 kg of cement, and mix it with water to prepare cement slurry (water-cement ratio of 0.6:1), pump the cement slurry, prevent water from passing through, and complete the lubrication of the pumping pipeline.
[0079] Step 2: After the cement slurry completely enters the pipeline, start pumping concrete;
[0080] Water, the sealing element, the cement slurry, and the concrete will flow out of the pipeline outlet in sequence. When the concrete flows out of the pipeline outlet, immediately connect a concrete spraying hose at the pipeline outlet, and mix high-pressure air and liquid accelerating admixture at the nozzle to spray out the concrete for wet spraying support work;
[0081] Step 3: After the wet shotcreting of concrete is completed, stop the concrete preparation, start pumping cement slurry at the inlet of the pipeline. After the cement slurry completely enters the pipeline, insert a seal, and then pump water.
[0082] The water-cement ratio of the cement slurry in Step 3 is 0.5:1, and the cement slurry is prepared on-site.
[0083] The seal is a sponge ball.
[0084] As an implementable mode, the seal can be a cement bag or other existing materials that can meet the requirement of separating water and cement slurry to avoid their contact. The seal separates water and cement slurry and is conveyed along the pipeline with the pumping.
[0085] When pumping concrete over a long distance of 1000 m, first use 500 kg of cement, mix it with water to prepare and pump the cement slurry (water-cement ratio 0.5:1). Then insert multiple sponge balls as seals at the rear section of the cement slurry. Then continuously pump water until the concrete in the pipeline is cleaned up and the pipe washing work is completed, preventing water leakage due to an unsealed seal caused by a dirty pipeline during the next concrete pumping and avoiding pipeline blockage as much as possible.
[0086] As an implementable mode, the cement slurry in Step 1 can also be replaced by existing technologies such as lubricants and mortar that can achieve the pipeline lubrication effect.
[0087] It should be noted that during the cleaning step, since the front section of the pipeline is pumped concrete and its pumping pressure is greater than that in the lubrication stage. Also, first pump the cement slurry and then pump water. Since the seal cannot completely avoid the contact between water and cement slurry, in order to prevent some water from contacting the cement slurry and diluting the cement slurry, which may cause water to enter the concrete section and lead to concrete segregation and pipe blockage, the cement slurry in the cleaning step is relatively thicker than that in the lubrication stage.
[0088] The above embodiments are only the preferred embodiments of the present invention and do not limit the scope of implementation of the present invention. Therefore, any equivalent changes or modifications made according to the structure, features, and principles described in the scope of the present invention patent should be included in the scope of the patent application of the present invention.
Claims
1. A long distance pumping concrete for wet spraying, characterized in that: Made from the following raw materials in parts by weight: 465-505 parts of cement, 825-875 parts of sand, 825-875 parts of gravel, 5-8 parts of admixture and 175-215 parts of water; The admixture is made of the following raw materials: a water reducing agent, a retarder, a slump retaining agent, and an air entraining agent, and the mass ratio of the water reducing agent, the retarder, the slump retaining agent, and the air entraining agent is: 5.5-6.5: 2.5-3.5: 0.5-1: 0-0.
5.
2. A long distance pumping concrete for wet spraying according to claim 1, characterized in that: The mass ratio of the water reducing agent, the retarder, the collapse retaining agent and the air entraining agent in the admixture is 6:3:0.75:0.
25.
3. The long-distance pumping concrete for wet spraying according to claim 1 is characterized in that: The cement is silicate cement, and the water reducer is a polycarboxylate water reducer or a naphthalene water reducer.
4. The long-distance pumping concrete for wet spraying according to claim 1 is characterized in that: The sand has a mud content of less than or equal to 3% and a mud block content of less than or equal to 1%.
5. The long-distance pumping concrete for wet spraying according to claim 1, characterized in that: The stone particle size is less than or equal to 15 mm.
6. A method for preparing a long-distance pumping concrete for wet spraying according to any one of claims 1 to 5, characterized in that: The following steps are involved: Step 1, mixing sand and gravel in proportion and stirring evenly to obtain a sand and gravel mixture; Step 2: Start the mixer and add sand and gravel mixture, cement, water and admixture into the mixer in proportion; Step 3: After the raw materials are added, stir them thoroughly in a blender for 4 minutes to complete the preparation.
7. An application of a long-distance pumping concrete for wet spraying according to any one of claims 1 to 5, characterized in that: The following steps are involved: Step 1: first pump water to the pipeline inlet, insert the seal after the water completely enters the pipeline, and then pump cement slurry, and the seal is transported toward the pipeline outlet along with the water and cement slurry; Step 2: After the cement slurry has completely entered the pipeline, start pumping concrete; Water, seals, cement slurry, and concrete will flow out from the pipe outlet in sequence. When concrete flows out of the pipe outlet, immediately connect the concrete spraying hose to the pipe outlet, mix high-pressure air and liquid quick-setting agent at the nozzle to spray the concrete for wet spraying support work; Step 3: After the concrete wet spraying work is completed, start pumping cement slurry at the pipe inlet. When the cement slurry has completely entered the pipe, plug in the seal and then pump water.
8. The use of long-distance pumping concrete for wet spraying according to claim 7, characterized in that: The sealing element is a sponge ball.
9. The use of long-distance pumping concrete for wet spraying according to claim 7, characterized in that: The water-to-binder ratio of the cement slurry in step 1 is 0.6:
1.
10. The use of long-distance pumping concrete for wet spraying according to claim 7, characterized in that: The water-to-binder ratio of the cement slurry in step 3 is 0.5:1.