What are the differences in water-stopping effects between steel plates and waterstop strips? (Waterstop strips and steel plates)

Steel plates are typically 3mm thick, wider than 200mm, and usually 3 meters or 6 meters long, with 3 meters being the preferred length for easier transport.

During construction, ensure the steel plate is aligned with the wall's centerline; the weld between two plates should be full and double-sided, with an overlap of at least 200mm.

At wall corners, methods such as bending a single steel plate, T-shaped welding, and L-shaped welding are commonly used.

For supporting the steel plate, small reinforcing bars can be welded to the main reinforcement; when the steel plate passes through column stirrups, the stirrups can be broken to create an open stirrup, which is then welded to the steel plate.

Advantages and disadvantages: Steel plate waterstops require full welding at the joints, resulting in excellent performance, but the cost is significantly higher, and construction is slower.

The standard requires that for shear walls using water-stop steel plates, the wall thickness should not be less than 250 mm. The net distance between the water-stop steel plate and the reinforcing steel should be: wall thickness/2 - outer protective layer thickness 50 - diameter of the bidirectional reinforcing steel in the wall. When the wall thickness is 250 mm, 250/2 - 50 - 30 = 45 mm.

If the distance between the water-stop steel plate and the wall is too small, the concrete is prone to under-vibration during construction, resulting in honeycomb-like voids.

Therefore, when using water-stop steel plates, vibration must be strengthened at construction joints.

The weakest points in this water-stopping measure are the overlapping areas and 90° corners.

The weld at the 90° corner of the steel plate is extremely difficult to control, easily creating leakage points.

The welding construction at the steel plate corners should be considered a critical part of this process and controlled accordingly.

Water-stops can be fixed using additional reinforcing steel, special clamps, wire, and formwork.

When perforation is necessary, it should only be performed at the edge of the waterstop installation area, without damaging other parts.

For on-site connections, methods such as electric heating plate vulcanization bonding or cold bonding (for rubber waterstops) or welding (for plastic waterstops) can be used.

During construction, waterstops should not be exposed to direct sunlight for extended periods, should be protected from rain, and should not come into contact with highly polluting chemicals. During transportation and construction, avoid damage to the waterstop from machinery and reinforcing steel. During construction, the waterstop must be securely fixed to prevent displacement during concrete pouring and ensure its correct position within the concrete. Advantages and disadvantages: Concrete contains many sharp-edged stones and sharp reinforcing steel ends. Because the tear strength of plastics and rubber is 3-5 times lower than their tensile strength, once the waterstop is punctured or torn, the tear will expand without significant external force. Therefore, during waterstop positioning and concrete pouring, attention should be paid to the positioning method and pouring pressure to prevent punctures and maintain the waterstop's effectiveness.

During concrete pouring, waterstops, being made of soft rubber, are prone to deformation and unevenness, and their width is difficult to control. Tying them to reinforcing bars with wire can damage the waterstop, so construction companies generally find it troublesome and dislike using it.

What are the differences in waterstop effects between steel plates and waterstop strips? (Differences between waterstop strips and steel plates)

Steel plates are typically 3mm thick, wider than 200mm, and usually 3 meters or 6 meters long, with 3 meters being the preferred length for easier transport. During construction, efforts should be made to ensure the steel plate is aligned with the wall's centerline; the weld between two plates should be full and double-sided, with an overlap of at least 200mm. Wall corners are typically treated using methods such as bending a single steel plate, T-shaped welding, or L-shaped welding. Support welding of the steel plate can be done by welding small reinforcing bars to the main reinforcement; when the steel plate passes through column stirrups, the stirrups can be broken to create an open stirrup, which is then welded to the steel plate. Advantages and disadvantages analysis: While fully welding the joints of steel plate waterstops yields excellent results, it significantly increases costs and slows construction speed. Standard requirements stipulate that for shear walls using waterstop steel plates, the wall thickness should not be less than 250 mm, and the net distance between the waterstop steel plate and the reinforcing steel should be: wall thickness/2 - outer protective layer thickness 50 - diameter of the bidirectional reinforcing steel in the wall; when the wall thickness is 250 mm, 250/2 - 50 - 30 = 45 mm. If the distance between the waterstop steel plate and the wall is too small, the concrete is prone to under-vibration during construction, resulting in honeycomb-like voids. Therefore, when using waterstop steel plates, enhanced vibration is necessary at construction joints. The weakest points of this waterstop measure are the lap joints and 90° corners. Welding at the 90° corners of the steel plate is extremely difficult to control, easily creating leakage points. The welding construction at the steel plate corners should be considered a critical part of this process and controlled accordingly. Waterstops can be fixed using methods such as additional steel reinforcement, special clamps, wire, and formwork. When perforation is necessary, it should only be done at the edge of the waterstop installation area, avoiding damage to other parts. For on-site connections, methods such as electric heating plate vulcanization bonding (for rubber waterstops) or cold bonding or welding (for plastic waterstops) can be used. Waterstops should not be exposed to direct sunlight for extended periods, should be protected from rain, and should not come into contact with highly polluting chemicals. During transportation and construction, avoid damage to the waterstop from machinery and steel reinforcement. During construction, the waterstop must be securely fixed to prevent displacement during concrete pouring and ensure its correct position within the concrete. Advantages and disadvantages: Concrete contains many sharp-edged stones and sharp steel rebar ends. Since the tear strength of plastics and rubber is 3-5 times lower than their tensile strength, once a waterstop is punctured or torn, the tear will expand quickly without significant external force. Therefore, during waterstop positioning and concrete pouring, attention should be paid to the positioning method and pouring pressure to prevent puncture and maintain the waterstop's effectiveness. During concrete pouring, waterstops, being made of soft rubber, are prone to deformation and unevenness, and their width is difficult to control. If wire is used to tie them to the reinforcing bars, it damages the waterstop. Therefore, construction units generally find it troublesome and dislike using it.

What are the specifications for waterstop tie rods? (Waterstop, waterstop steel plate, waterstop tie rod)

I. Building Part

1. Settlement joints and expansion joints should not be set inside the protective unit. If necessary, explosion-proof settlement joints must be installed.

2. The walls, ceilings, and floors of enclosed passages, anti-toxic passages, decontamination rooms, filtration rooms, diffusion rooms, etc., should be smooth, clean, and easy to clean.

3. The top of the protective area of the civil defense basement (except for the areas described in item 2) is not allowed to be plastered or leveled with cement mortar.

4. Non-retractable air-raid shelter doors have a threshold, with a height difference of 150mm between the threshold and the building floor. Retractable air-raid shelter doors do not have a threshold, and the bottom edge of the door frame is at the same height as the building floor. The anchor hooks of the air-raid shelter door frame should extend into the structural layer.

5. When a protective airtight door is installed in a shaft, the outer surface of its door leaf must not protrude from the inner wall of the shaft. Blast wave resistant doors should be embedded in the wall.

6. Within 20mm of the air-raid shelter door frame, the wall plaster layer must not extend beyond the angle steel surface of the door frame.

7. Prefabricated components for peacetime-wartime conversion should be prepared simultaneously with the project, and storage locations for the components should be designated.

8. For wartime sealing points at entrances and exits, a trench should be reserved on the non-air-raid shelter side, and the anchor hooks of the embedded parts should extend into the structural layer. During peacetime, the wartime sealing frame should be painted or plastered with cement mortar and reinforced with wire mesh. After treatment, the words "Temporarily Sealed" should be marked on both sides of the wall.

II. Structural Part

9. The anchorage length laF of longitudinal reinforcing bars in reinforced concrete structural members is 1.05lad.

10. The upper layer reinforcement of the basement foundation slab must pass through the lower part of the upper main reinforcement of the foundation beam, and the lower layer reinforcement of the top slab must pass through the upper part of the lower main reinforcement of the top slab beam.

11. Tie bars (S-shaped, φ6, 500mm, staggered arrangement) must be provided on the top, bottom slabs, and exposed walls of the civil defense zone.

12. Reinforcing bars must be provided at the four corners of the entrances to the civil defense enclosure structure and sealed walls: 1000mm long, tied at a 45° angle; for walls 400mm thick, 2φ16 bars per corner; for walls thicker than 400mm, 3φ16 bars per corner.

13. The stirrups of the attached columns cut by the waterstop steel plate should be lapped and welded to the waterstop steel plate.

14. PVC conduits are not permitted for tie rods in the formwork of civil defense enclosure structures and airtight walls (both reinforced concrete interior walls), and a water-stop plate should be installed in the middle of the tie rod.

15. Wall reinforcement cut by pipes should be spot-welded to the through-wall pipe.

16. The reinforcement construction requirements at the junction of beams and edge columns, and at the junction of exterior walls and top/bottom slabs are as follows:

① The anchorage length of the longitudinal reinforcement on the outer side of the edge column extending into the ground or top beam should be 1.5 lad.

② When the thickness of the top slab is... III. Electrical Part

17. All cables (including various strong and weak current cables) laid within the enclosure structure, passing through exterior walls, walls exposed to air, protective airtight walls, and airtight walls, should be fabricated according to civil defense requirements. Cables directly passing through the exterior walls, airtight walls, protective airtight walls, and airtight walls of civil defense facilities should use hot-dip galvanized steel pipes with a wall thickness greater than 2.5 mm as conduits. The pipes should extend 100 mm out of the wall at both ends, with double-sided full-welded airtight ribs (δ 4, b 50) in the middle. The distance between adjacent conduit walls should be no less than 100 mm.

18. Four to six hot-dip galvanized steel pipes with a diameter of 50-80 mm and a wall thickness greater than 2.5 mm should be pre-embedded in the protective airtight doors and door frames of civil defense facilities' electrical shafts, personnel entrances, and connecting openings as spare pipes. Specifically, the pipes should extend 100 mm out of the wall at both ends, with double-sided full-welded airtight ribs (δ 4, b 50) in the middle.

19. Various busbar trunking and cable trays cannot directly pass through the airtight walls, door frame walls, exterior walls, and roofs of civil defense facilities. When it is necessary to pass through them, the busbars should meet the requirements for protective airtightness, and the cable trays should be replaced with conduit installation, with one cable per conduit.

20. Indicator lights and distribution boxes on both sides of the exposed walls, door frame walls, and exterior walls of civil defense facilities must be surface-mounted; concealed installation is not permitted.

21. When installing junction boxes and transition boxes on both sides of the exposed walls, door frame walls, and exterior walls of civil defense facilities, avoid having junction boxes on both sides in the same location.

22. In Class A air defense shelters, including rescue stations, air defense professional team projects, personnel shelter projects, and supporting facilities, all auxiliary equipment and pipelines, except for the diesel generator sets which may not be installed under normal circumstances, must be properly installed in the diesel power stations.

23. After the main structure of the civil defense facility has been poured with concrete, no further drilling or trenching is permitted.