In the field of engineering construction, refined rolled thread bar systems are a frequent reinforcement method and are widely used in bridges, tunnels, high-rise buildings, and other projects. This system effectively improves the load-bearing capacity and stability of the structure by inserting threaded rods into concrete and then filling the gap between the rebar and concrete with an anchoring agent through grouting. The refined rolled thread bar system is composed of a refined rolled thread bar, coupler, hex nut, and flat plate, with characteristics of high strength, flexible construction, and wide application range. It can be used as soil nails, rock bolts, micropile, and other structures for slope support, dam reinforcement, mountain landslide control, foundation uplift control, etc. The refined rolled thread bar system construction requires several steps: drilling holes, installing bolts, nuts, and plates, grouting, and sealing holes. Grouting is the most important part of the whole construction process. It is a construction technique of injecting cement slurry or other slurries into water-bearing fractures, voids, or unstable strata through drilling holes to stop water or reinforce the stratum. It plays a decisive role in the construction quality of refined rolled thread bar systems.
Preparation before grouting
Before starting grouting operations, the preparations are as follows:
Material preparation
Raw materials such as threaded rods, anchoring agents, cement, sand, and water should meet the design requirements and ensure material quality.
On-site processing
Clean the working surface to ensure that there is no debris or water on the site, and remove rust from the threaded rods to ensure that the grouting operation proceeds smoothly.
Technical briefing
Before the grouting operation, the operator should be briefed on the technical disclosure and clarify the operating procedures, quality requirements, and safety precautions.
Grouting method
Refined rolled thread bar system contains an anchor section and a free section. Among them, the area wrapped by corrugated pipe is the anchoring section, and the interior of the anti-corrosion structure needs to be grouted. The area wrapped by smooth plastic pipe is a free section, and no grouting is required in the pipe.
Grouting method of anchoring section
1. Connect bottom end cap and corrugated pipes, and insert threaded rod and coupling sleeve into corrugated pipes.
2. Insert the grouting pipe and fill it with cement grout. After filling, screw the upper-end cap tightly.
3. Put thermoplastic tube on the connection between end cap and tube for heating.
Grouting method of threaded rod
1. Assemble the threaded rod and internal grouting solidification anti-corrosion system and put it into the hole.
2. Insert the exhaust pipe and the grouting pipe. Grouting pipe should reach the bottom of the hole, grouting method is pulling out the grouting pipe while grouting, and start the grouting pipe should be pulled out after grouting to 5m.
3. Use PO 42.5 ordinary Portland cement to prepare cement slurry, the water-cement ratio is controlled at 0.4-0.45, and the grouting pressure is controlled at 0.4-0.6Mpa until the orifice overflows. At this time, all the exhaust pipes should be pulled out and the grouting pipes should not be pulled out.
4. Use cement bag wet clay plus steel plate to seal and tightly plug, grout at 0.4-0.6Mpa stably for 5min, then pull out the grouting tube.
5. The grouting volume should be greater than 1.2 times its theoretical calculated volume.
6. After grouting, install the plate and nut.
Inspection after grouting
After the grouting construction, the quality check is as follows:
Check whether there are gaps around the threaded rods
By tapping the finely threaded rods, listen to the sound to determine whether there is a gap around it. If there is a gap, we need to re-grouting operation.
Check the fullness of the slurry
Observe the fullness of the slurry around the threaded rods. If there is under-fullness, it is necessary to replenish the grout in time.
Check the tightness of the connection
After the grouting is completed, check whether the joints are tightly connected. If there is leakage, take corresponding measures to deal with it.
Precautions when using refined rolled thread bar
1. It is prohibited to perform welding and gas-cutting processes next to refined rolled thread bars. These operations may adversely affect the material and performance of the steel bars, thereby reducing their load-bearing capacity and service life.
2. Regularly inspect the refined rolled thread bar. If the steel bars are cracked or showing signs of severe wear, staff should replace them immediately and mark them as not in use. At the same time, if the new nut cannot secure the finely refined rolled thread bar, it indicates that the steel bar may be damaged and should be scrapped. In addition, if old nuts cannot match any refined rolled thread bar, there may be an issue with the nut, and it should also be scrapped.
3. Carefully record the usage of the refined rolled thread bar. Include stretch, disassembled parts for traceability and evaluation if needed.
4. Pay attention to cutting and connecting operations during construction. The length of the refined rolled thread bar is according to the requirements of the construction party, but arc or oxygen arc cutting is prohibited. When connecting, connectors or nuts with internal threads should be used for connection and anchoring to ensure the accuracy and strength of the connection.
5. During use, the operator should avoid excessive bending or twisting of the refined rolled thread bars to prevent plastic deformation or fracture. Meanwhile, during storage and transportation, we should pay attention to avoid collision and extrusion of the rebar to keep its good shape and performance.
6. When using a refined rolled thread bar, we should strictly abide by the relevant safety regulations and operating procedures to ensure the safety of personnel and equipment. Especially when working at height or in confined spaces, it’s essential to take necessary safety measures to prevent accidents.
Conclusion
In short, the grouting method of the refined rolled thread bar system is one of the crucial links in the entire reinforcement process. Through reasonable grouting methods and strict construction quality control, the anchoring effect of the refined rolled thread bar system can be effectively improved, further ensuring the safety and stability of the construction project. With the advancement of science and technology and the continuous improvement of engineering technology requirements, the grouting method of the refined rolled thread bar system still needs to be continuously improved and optimized to provide them with better quality and efficient technology support while adapting to more engineering needs.
