A cement-based sleeve grout and a method for preparing the same

Abstract

The application discloses a cement-based sleeve grouting material, which is composed of the following components in parts by weight: ordinary cement 15-50 parts, special cement 1-20 parts, aggregate 30-55 parts, mineral admixture 2-20 parts, plastic expansion agent 0.01-1 part, expansion agent 1-10 parts, early strength agent 0.05-2 parts, retarding agent 0.05-5 parts, high-performance additive 0.01-1 part, steel fiber with grid-shaped hollow trunk 5-30 parts, and water-material ratio 0.10-0.17. The sleeve grouting material for fabricated buildings has a wide temperature range and can be stirred with mixing water to obtain a high-strength grouting material with excellent construction performance under the condition of-5-30 DEG C, the 28d compressive strength of which is greater than or equal to 120 MPa, the initial fluidity of which is greater than or equal to 320 mm, and the 30min fluidity of which is greater than or equal to 260 mm, and the compressive strength is much higher than that of the sleeve grouting material on the market, and the cracking risk is relatively small.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, specifically relating to a cement-based sleeve grouting material and its preparation method. Background Technology

[0002] Currently, the country is vigorously developing prefabricated buildings. The field of prefabricated concrete construction is mainly divided into two areas: precast bridges and civil engineering buildings. Prefabricated buildings have the characteristics of high construction efficiency, controllable quality, energy saving and environmental protection. With the continuous updating and iteration of prefabricated building technology, the requirements for cement-based materials in prefabricated buildings are also getting higher and higher. Sleeve grouting material is used as a connecting material in prefabricated buildings. Sleeve grouting material is mainly used to connect prefabricated components and the bottom composite slab.

[0003] The standard for grouting sleeves used in prefabricated bridge construction (D part / DGTJ 08-2160-2021) was officially implemented in February 2022. The standard clearly stipulates that the compressive strength of the grouting sleeve should not be less than 100MPa. However, the strength of commonly used grouting sleeves for prefabricated buildings on the market is generally between 110 and 120MPa, which is not high. The grouting sleeve joints made from this material cannot meet the requirements of the standard, which seriously restricts the quality of the engineering structure.

[0004] The quality of the sleeve grouting material directly restricts the quality of grouting construction. Currently, the compressive strength of commonly available sleeve grouting materials is around 100MPa, with significant shrinkage. This results in low compressive strength of the grouting sleeve joints, leading to the failure of prefabricated building projects during the acceptance process. Failure to pass the acceptance process can cause great trouble for the project, resulting in the removal of prefabricated components that have already been grouted, causing significant losses.

[0005] Therefore, the development of a prefabricated grouting material for prefabricated buildings with low material shrinkage, high compressive strength, and high tensile strength of grouting sleeve joints can actively promote the development of the prefabricated industry. Summary of the Invention

[0006] The purpose of this invention is to provide a low-temperature cement-based sleeve grouting material for prefabricated buildings that can be constructed normally under low-temperature conditions, has early strength, high strength, good expansion performance and is not easy to crack, and its preparation method.

[0007] To achieve the above objectives, the following technical solution is adopted: A cement-based sleeve grouting material, the composition of which is as follows by weight parts: The ingredients are: 15-50 parts ordinary cement, 1-20 parts special cement, 30-55 parts aggregate, 2-20 parts mineral admixture, 0.01-1 part plastic expansion agent, 1-10 parts expansion agent, 0.05-2 parts early strength agent, 0.05-5 parts retarder, 0.01-1 part high-performance admixture, 5-30 parts steel fiber with a mesh-like hollow body, and a water-to-material ratio of 0.10-0.17.

[0008] The optimized solution comprises the following components by weight: 45 parts ordinary cement, 5 parts special cement, 40 parts aggregate, 6.84 parts mineral admixture, 0.05 parts plastic expansion agent, 3 parts expansion agent, 0.05 parts early strength agent, 0.05 parts retarder, 0.1 parts workability improver, 0.1 parts high-performance admixture, 6 parts steel fiber with a mesh-like hollow structure, and a water-to-material ratio of 0.12 to 0.15.

[0009] According to the above scheme, the ordinary cement is one of ordinary Portland cement, Portland cement, and slag cement, and its strength grade is not lower than 52.5.

[0010] According to the above scheme, the special cement is sulfoaluminate cement or is a compound of sulfoaluminate cement, high alumina cement and magnesium phosphate cement; in the compounding scheme, the weight proportions are 1-25 parts of sulfoaluminate cement, 1-10 parts of high alumina cement and 1-10 parts of magnesium phosphate cement.

[0011] According to the above scheme, the aggregate is one of river sand, quartz sand, corundum, bauxite, silicon carbide, and steel shot; the gradation composition is 25~60wt% for 10-30 mesh and 35~70wt% for 30-100 mesh.

[0012] According to the above scheme, the mineral admixture is at least one of ultrafine mineral powder, lime, microsphere powder, fly ash, gypsum powder, silica fume, heavy calcium carbonate powder, kaolin, and wood ash.

[0013] According to the above scheme, the plastic expanding agent is a compound of an azo compound and a zinc salt in a 1:1 mass ratio. In the optimized scheme, the azo compound is azodicarbonamide, and the zinc salt is one of zinc oxide, zinc stearate, and zinc carbonate.

[0014] According to the above scheme, the expanding agent is at least one of calcium oxide expanding agents, sulfoaluminate expanding agents, and magnesium oxide expanding agents.

[0015] According to the above scheme, the retarder is at least one of tartaric acid, boric acid, sodium gluconate, citric acid, and sucrose; the accelerator is at least one of lithium sulfate, lithium carbonate, sodium sulfate, and sodium silicate. The ratio of retarder to accelerator can be adjusted according to the expansion time of the expanding agent. After determining the construction temperature, the shrinkage curve of the expanding agent is measured using a non-contact corrugated pipe. The setting time of the grout is adjusted by using the accelerator and retarder to control the final setting time to coincide with the peak expansion of the expanding agent.

[0016] According to the above scheme, the steel fiber with a mesh-like hollow body has a length of 2~25mm and a diameter of 0.12~2mm; the length of the mesh-like hollow body accounts for 60~80% of the total length of the steel fiber, and its two ends are solid, with the solid part accounting for 20~40% of the total length of the steel fiber.

[0017] According to the above scheme, the high-performance admixture is a compound of polycarboxylate superplasticizer, polyether modified silicone defoamer, and water-retaining agent. The polycarboxylate superplasticizer is 3-6 parts by weight, the polyether modified silicone defoamer is 2-7 parts, and the water-retaining agent is 3-6 parts. The water-retaining agent is at least one of cellulose ether, vinaigrette, and biopolysaccharide gum.

[0018] The present invention also provides a method for preparing the above-mentioned cement-based sleeve grouting material, comprising the following steps: (1) The expansion agent is premixed with steel fibers having a mesh-like hollow body for later use; (2) Take 10% of ordinary cement and mix it with plastic expansion agent, retarder, early strength agent and high performance admixture for 3-5 minutes; (3) Then add the remaining ordinary cement, special cement and mineral admixture and mix for 3-5 minutes; (4) Add aggregate and water and mix in a mixer at 100-500r / min for 4-10min. Finally, add expansion agent and steel fiber premix with mesh-like hollow body and mix for 2-5min to obtain grout.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: The prefabricated building sleeve grouting material of the present invention has a wide applicable temperature range. It can be obtained by mixing with mixing water at temperatures ranging from -5 to 30°C, resulting in a high-strength grouting material with excellent construction performance. The 28-day compressive strength is ≥120MPa, the initial flowability is ≥320mm, and the 30-minute flowability is ≥260mm. The compressive strength is much higher than that of sleeve grouting materials currently on the market, while the risk of cracking is relatively low.

[0020] This invention involves premixing the expanding agent with hollow steel fibers and then adding it to the grout. The hollow steel fibers are filled with the expanding agent, which expands and causes the steel fibers to bulge, resembling a bamboo joint structure. This significantly improves the pull-out strength of the grout sleeve joint and also restricts the self-drying shrinkage of the grout, reducing the shrinkage of the sleeve grout. This enhances the adhesion between the grout and the sleeve and reinforcing bars, effectively transferring force and ensuring the reliability of the joint connection and the overall structural safety.

[0021] The prefabricated building sleeve grouting material of the present invention, by modifying the steel fibers, increases the diameter of the middle part of the steel fibers after the expansion agent expands, which can significantly improve the pull-out strength of the grouting sleeve joint and ensure the safety of the engineering structure. Detailed Implementation

[0022] The following embodiments further illustrate the technical solution of the present invention, but are not intended to limit the scope of protection of the present invention.

[0023] The specific implementation section provides a steel fiber with a mesh-like hollow body, 0.5 mm in diameter and 12 mm in length. The two ends of the steel fiber are solid, with the solid portion accounting for 30% of the total fiber length. The middle of the steel fiber is processed into a mesh-like hollow body, with the hollow body accounting for 70% of the total fiber length. The manufacturing process of the steel fiber with the mesh-like hollow body utilizes a high-precision CNC micro-punching die. A customized die head is used for ultra-fine diameter specifications of 0.12–2 mm to precisely punch the leveled steel strip with double-sided staggered punching. The upper die presses micro-concave arc grooves, and the lower die simultaneously presses corresponding concave arc grooves. The upper and lower arc grooves are precisely closed, forming a closed micro-hollow cylindrical cavity integrally formed in the steel strip body. The outer diameter of the cavity is strictly controlled within the range of 0.12–2 mm. Integral steel strip connecting ribs are reserved between adjacent micro-hollow cavities, forming a continuous array of "ultra-fine hollow monomers + internet grid ribs" strip-shaped blank.

[0024] Unless otherwise specified, all raw materials used in the specific implementation methods were obtained through commercial purchase.

[0025] Example 1 45 parts ordinary cement, 5 parts special cement, 40 parts aggregate, 6.84 parts mineral admixture, 0.1 parts plastic expansion agent, 3 parts expansion agent, 0.05 parts retarder, 0.05 parts early strength agent, 0.1 parts high-performance admixture, and 6 parts steel fiber with a mesh-like hollow body.

[0026] The special cement is a blend of sulfoaluminate cement, high-alumina cement, and magnesium phosphate cement in a mass ratio of 2:1:1. The plasticizing agent is a blend of azo compound and zinc salt in a mass ratio of 1:1. The mineral admixture is a mixture of microsphere powder, gypsum powder, and wood ash. The expanding agent is a calcium oxide-based expanding agent. The early-strength agent is lithium carbonate; the retarder is boric acid. The high-performance admixture is a blend of polycarboxylate superplasticizer, polyether-modified silicone defoamer, and water-retaining agent, with the following proportions by weight: 3 parts polycarboxylate superplasticizer, 2 parts polyether-modified silicone defoamer, and 3 parts water-retaining agent.

[0027] The preparation method is as follows: (1) The expansion agent is premixed with steel fibers having a mesh-like hollow body for later use; (2) Take 10% of ordinary cement and mix it with plastic expansion agent, retarder, early strength agent and high performance admixture for 3-5 minutes; (3) Then add the remaining ordinary cement, special cement and mineral admixture and mix for 3-5 minutes; (4) Add aggregate and water and mix in a mixer at 100-500 r / min for 4-10 min until homogeneous. Finally, add expansion agent and premixed steel fiber with a mesh-like hollow body and mix for 2-5 min to obtain grouting material. Use GTQ4Z-40 grouting sleeve and 40mm diameter HRB400E steel bar to make grouting sleeve joints according to relevant construction specifications.

[0028] Example 2 43 parts ordinary cement, 7 parts special cement, 40 parts aggregate, 6.84 parts mineral admixture, 0.1 parts plastic expansion agent, 3 parts expansion agent, 0.05 parts retarder, 0.05 parts early strength agent, 0.1 parts high-performance admixture, and 6 parts steel fiber with a mesh-like hollow body.

[0029] Example 3 40 parts ordinary cement, 10 parts special cement, 40 parts aggregate, 6.84 parts mineral admixture, 0.1 parts plastic expansion agent, 3 parts expansion agent, 0.05 parts retarder, 0.05 parts early strength agent, 0.1 parts high-performance admixture, and 6 parts steel fiber with a mesh-like hollow body.

[0030] Example 4 40 parts ordinary cement, 5 parts special cement, 45 parts aggregate, 6.84 parts mineral admixture, 0.1 parts plastic expansion agent, 3 parts expansion agent, 0.05 parts retarder, 0.05 parts early strength agent, 0.1 parts high-performance admixture, and 6 parts steel fiber with a mesh-like hollow body.

[0031] Comparative Example 1 Repeat Example 1, except that the addition of steel fiber is removed, and everything else remains the same.

[0032] Comparative Example 2 Repeat Example 1, except that the steel fibers with a mesh-like hollow body are replaced with solid steel fibers of the same size, while the rest remain unchanged.

[0033] The products obtained from the above embodiments and comparative examples were characterized, as shown in Table 1.

[0034] Table 1

[0035] As shown in Table 1, the tensile strength of Comparative Examples 1 and 2 is much lower than that of Example 1, and the shrinkage of Comparative Examples 1 and 2 is higher than that of Example 1. Therefore, it can be concluded that after steel fiber is modified, it has a good effect on improving the pull-out effect of the grouting sleeve pull-out joint, and the shrinkage of the material is significantly smaller.

Claims

1. A cement-based sleeve grouting material, characterized in that... The composition by weight is as follows: The ingredients are: 15-50 parts ordinary cement, 1-20 parts special cement, 30-55 parts aggregate, 2-20 parts mineral admixture, 0.01-1 part plastic expansion agent, 1-10 parts expansion agent, 0.05-2 parts early strength agent, 0.05-5 parts retarder, 0.01-1 part high-performance admixture, 5-30 parts steel fiber with a mesh-like hollow body, and a water-to-material ratio of 0.10-0.

17.

2. The cement-based sleeve grouting material as described in claim 1, characterized in that... The composition by weight is as follows: 45 parts ordinary cement, 5 parts special cement, 40 parts aggregate, 6.84 parts mineral admixture, 0.05 parts plastic expansion agent, 3 parts expansion agent, 0.05 parts early strength agent, 0.05 parts retarder, 0.1 parts high performance admixture, 6 parts steel fiber with a mesh-like hollow body, and a water-to-material ratio of 0.12~0.

15.

3. The cement-based sleeve grouting material as described in claim 1, characterized in that... The ordinary cement is one of ordinary Portland cement, Portland cement, or slag cement, with a strength grade of not less than 52.

5.

4. The cement-based sleeve grouting material as described in claim 1, characterized in that... The special cement is sulfoaluminate cement or a mixture of sulfoaluminate cement, high-alumina cement, and magnesium phosphate cement; in the mixture, by weight, there are 1-25 parts of sulfoaluminate cement, 1-10 parts of high-alumina cement, and 1-10 parts of magnesium phosphate cement.

5. The cement-based sleeve grouting material as described in claim 1, characterized in that... The aggregate is one of river sand, quartz sand, corundum, bauxite, silicon carbide, and steel shot; the gradation composition is 25~60wt% for 10-30 mesh and 35~70wt% for 30-100 mesh.

6. The cement-based sleeve grouting material as described in claim 1, characterized in that... The mineral admixture is at least one of the following: ultrafine mineral powder, lime, microsphere powder, fly ash, gypsum powder, silica fume, heavy calcium carbonate powder, kaolin, and wood ash.

7. The cement-based sleeve grouting material as described in claim 1, characterized in that... The plastic expansion agent is a compound of azo compound and zinc salt in a mass ratio of 1:

1.

8. The cement-based sleeve grouting material as described in claim 1, characterized in that... The expanding agent is at least one of calcium oxide expanding agents, sulfoaluminate expanding agents, and magnesium oxide expanding agents; the retarder is at least one of tartaric acid, boric acid, sodium gluconate, citric acid, and sucrose; the early strength agent is at least one of lithium sulfate, lithium carbonate, sodium sulfate, and sodium silicate; the high-performance admixture is a compound of polycarboxylate superplasticizer, polyether-modified silicone defoamer, and water-retaining agent, wherein the polycarboxylate superplasticizer is 3-6 parts by weight, the polyether-modified silicone defoamer is 2-7 parts, and the water-retaining agent is 3-6 parts; the water-retaining agent is at least one of cellulose ether, gluten gum, and biopolysaccharide gum.

9. The cement-based sleeve grouting material as described in claim 1, characterized in that... The steel fiber with a mesh-like hollow body has a length of 2-25 mm and a diameter of 0.12-2 mm; the length of the mesh-like hollow body accounts for 60-80% of the total length of the steel fiber, and its two ends are solid, with the solid part accounting for 20-40% of the total length of the steel fiber.

10. A method for preparing the cement-based sleeve grouting material according to any one of claims 1-9, characterized in that... Includes the following steps: (1) The expansion agent is premixed with steel fibers having a mesh-like hollow body for later use; (2) Take 10% of ordinary cement and mix it with plastic expansion agent, retarder, early strength agent and high performance admixture for 3-5 minutes; (3) Then add the remaining ordinary cement, special cement and mineral admixture and mix for 3-5 minutes; (4) Add aggregate and water and mix in a mixer at 100-500r / min for 4-10min. Finally, add expansion agent and steel fiber premix with mesh-like hollow body and mix for 2-5min to obtain grout.

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