Foundation bolt grouting

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:) 1. Self-weight method: The self-weight method is a technique used in the application of cement-based grouting materials, taking advantage of the good fluidity of these materials to allow them to flow freely within the grouting area, thereby meeting the requirements for grouting. 2. High-position funnel method: This method is employed in cement-based grouting applications when the fluidity of the materials alone is not sufficient to meet the requirements; it involves increasing the potential energy of the grouting material to fulfill the grouting needs. 3. Pressure grouting method: The pressure grouting method is a technique used in the application of cement-based grouting materials, wherein grouting pressure equipment is employed to meet the requirements for grouting. Construction preparation: 1. Before using cement-based grouting materials, mixing equipment, grouting apparatus, formwork, and curing materials should be prepared ； 2. The acceptance of cement-based grouting materials shall comply with the specifications in the table: Type, compressive strength (MPa), flowability (mm), vertical expansion rate (%), and bond strength to steel bars (round steel)/MPa – at 1 day, 3 days, and 28 days. Initial values: at 1 day and 28 days. SS-80: ≥30, ≥50, ≥80, ≥230, ≥0.2, ≥4; SS-60: ≥22, ≥50, ≥65; SS-50: ≥20, ≥45, ≥60; SS-40: ≥15, ≥40, ≥55. 3. The acceptance of cement-based grouting materials is based on laboratory tests, and the test items to be checked include flowability, vertical expansion rate, and compressive strength. 4. Preparation of cement-based grouting material: • When mixing the cement-based grouting material, the amount of water to be used is generally that recommended on the product certificate supplied with it. Potable water should be used for mixing purposes; when other water sources are employed, they must comply with the requirements of the current \"Standards for Water Used in Concrete Mixing\" (JGJ63). The mixing of cement-based grouting materials can be carried out either by mechanical mixing or by manual mixing. When mechanical stirring is used, the stirring time is generally 1–2 minutes. When using manual stirring, 2/3 of the water amount should be added first and stirred for 2 minutes; thereafter, the remaining water amount should be added and stirring continued until uniformity is achieved. • During winter construction, cement-based grouting materials and mixing water must comply with the relevant provisions of the current \"Code for Construction and Acceptance of Reinforced Concrete Structures\" (GB50204). • It is strictly prohibited to add any admixtures or supplementary materials to the cement-based grouting materials when using them on site. Additive materials refer to fly ash, talc powder, slag, etc. 5. Construction machinery and equipment are mainly divided into 3 categories: (1) Mixing equipment, which includes concrete mixers or mortar mixers for mechanical mixing, as well as mixing tanks, shovels, etc. for manual mixing. (2) Grouting equipment includes a high-level funnel (with a volume greater than 0.2 m3), brackets, flow channels, grouting pipes, pipe fittings, and mortar. (3) Forms and curing materials include forms, release agents, plastic film, straw bags, rock wool blankets, etc. Anchoring of foot bolts: 1. The common forms of foot bolts are shown in Figure 2. Holes should be drilled or pre-existing; the requirements for these holes depend on the bolt diameter, as specified below. Bolt diameter and distance from the hole wall: Bolt diameter (mm) – Distance from the steel bar surface to the hole wall (mm): 12–14: ≥8; 16–22: ≥15; 24–42: ≥20; 48–64: ≥30; >100: ≥50. 3. The burial depth of the bolts must meet the requirements specified in the design codes. 4. Construction preparation: 1. Cement-based grouting materials shall be used to anchor the foot bolts, and the process shall comply with the requirements of Appendix A. 2. When drilling holes for the foundation bolts, the strength of the foundation concrete must be at least 20 MPa; the horizontal deviation of the bolt holes shall not exceed 2 mm, and the vertical deviation shall not exceed 1%. 3. The oil and rust on the anchor bolts must be completely removed. 4. After drilling the hole, it should be cleaned of debris and dust, any accumulated water removed, its depth checked, and the hole’s opening temporarily sealed. Before anchoring, moisten the hole with water, and remove any water accumulated inside it before grouting. 5. After the bolt is inserted, its horizontal position and the height of its top should be adjusted, and it should then be secured. 5. The preparation of cement-based grouting materials shall be carried out in accordance with Article 4 of the construction preparation provisions of these regulations, except that the water amount shall be reduced by 1%-2%. 6. When using cement-based grouting material to anchor anchor bolts, the following requirements must be met: 1. Pour the mixed cement-based grouting material into the bolt holes; shaking or tamping is strictly prohibited during the grouting process, and the bolts must not be adjusted after the grouting is complete. 2. It is difficult to pour grout directly during construction; a flow channel is often used to assist with the process. 3. During the grouting process, seepage was observed on the surface; therefore, dry cement-based grouting material was applied to absorb the moisture. Appendix A: Construction Process for Anchoring Foot Bolts – Secondary Grouting of Equipment 1. Before carrying out the secondary grouting of the equipment, it is necessary to select the appropriate grouting method based on the actual conditions. 2. Preparation for construction: 1. Clean the surface of the equipment foundation; there should be no debris such as gravel, loose mortar, dust, oil stains, or release agents. 24 hours before grouting, the surface of the equipment foundation should be thoroughly moistened. 1 hour before grouting, any accumulated water should be drained. 2. Set up formwork according to the grouting construction drawings; the formwork shall not be grouted. 3. The elevation of the top surface of the slab should be 50 mm higher than the upper surface of the equipment base. 4. If grout seeps out during pouring, it must be addressed promptly. 5. For the secondary grouting of cement-based grouting materials, the process shall meet the requirements of Appendix B. 6. The preparation of cement-based grouting materials shall be carried out in accordance with Article 4 of the construction preparation provisions of these regulations. 7. Grouting of longer equipment or track foundations (see grouting methods) shall be carried out in segments. It is advisable to send 10M per segment. 8. When grouting using the high-position funnel method, it is easy to start grouting from the center of the equipment base (see grouting method). 9. When performing secondary grouting with cement-based grouting materials, the following requirements must be met: 1. For secondary grouting using cement-based grouting materials, grouting should be carried out from one side until it overflows to the other side; grouting from all four sides simultaneously is not allowed. 2. Once grouting begins, it must be carried out continuously without interruption, and the grouting time should be shortened as much as possible. 3. Tamping is strictly prohibited during grouting; if necessary, bamboo strips can be used to guide the flow. 4. The thickness of each grouting layer should not exceed 100 mm. 5. For equipment foundations with shear pockets, those pockets should be grouted first; secondary grouting can be carried out after 24 hours. 6. After the grouting of the equipment foundation is completed, any parts that need to be removed should be dealt with before grouting begins. 7. The vibrations from machines that are still in operation must not be transmitted to the equipment foundation that is to be grouted; if this happens, the machine should be shut down during the second grouting process in order to avoid damaging the Not yet hardened grouting layer. The shutdown procedure should comply with the requirements specified in Article 3 on machine shutdown time in the curing section of these regulations. Appendix B: Process for curing secondary grouting 1. After grouting is completed, a curing agent should be sprayed immediately, or plastic film should be applied, with straw bags or rock wool blankets placed on top. 2. During winter construction, the curing measures shall also comply with the relevant provisions of the current \"Code for Construction and Acceptance of Reinforced Concrete Structures\" (GB50204). Other curing methods can also be employed during winter construction. 3. Once the cement-based grouting material has reached the time for removing the film, equipment installation can proceed. The specific times are indicated in the table below: Relationship between daily minimum temperature (°C), time for removing the film, and curing time. Daily minimum temperature (°C): -10 to 0 – 96 hours; 40 to 57 – 140 hours; 55 to 15 – 187 hours; >15 – 247 hours. Determination of environmental temperature, time for removing the film, and curing time: 1. Determination of the time for removing the film: The 30% of the 28-day strength of the grouting material (20 MPa) is used as the basis for determining the time for removing the film. Acceptance criteria for cement-based grouting materials: Daily minimum temperature (°C): -10 to -5 – 50 hours; 5 to 15 – 72 hours; >15 – 24 hours. Compressive strength (MPa): 21, 23, 23, 25, 27. Note: These test results are based on the standard JC475 for concrete antifreezing agents. The experimental data are shown in the table below: 2. Determination of curing time The curing time is determined based on the expansion value reaching 0.02%; the specific experimental data are provided in the table below: Time required for the expansion value to reach 0.02% at different temperatures Minimum temperature (°C): -10, -5, 0, 5, 15, >15 Time (hours): 14, 12, 10, 7, 5, 4 Expansion value (%): 0.02, 40.02, 30.03, 0.027, 0.031, 0.035