I. Overview

Bentonite waterproof blanket is a kind of waterproof construction method. Its construction process has certain advantages over other waterproof constructions, and the requirements for the base layer are relatively low. First, the concrete base layer must be hard, with a smooth surface and no cracks, peeling, and looseness. Second, the concrete surface should be leveled as necessary, and all the yin and yang corners should be chamfered with bentonite particles or bentonite sealant to form a 5cmx5em chamfer; third, the bentonite construction area must be dry, clean and free of debris.

The construction of bentonite waterproof blanket has one thing in common with other waterproof methods, that is, it cannot be constructed in bad weather, such as rain, snow and windy weather.

Second, the specific construction method of bentonite waterproof blanket

1. Construction process

Before the construction of the bentonite waterproof blanket, a layer of bentonite particles should be sprinkled first, and the dosage is 3kg/m3.

2. Waterproof blanket blanking

Before cutting, the site must be inspected, and the laying plan should be determined according to the characteristics of the project. The principle of the plan should be to minimize the overlap of the waterproof blanket and save materials. Depending on the width of the waterproof blanket, it can be laid vertically or horizontally.

The blanking should be accurate, there may be a little surplus, and there should be no shortage; unqualified blanking is strictly prohibited.

3. Fixing the waterproof blanket

The facade of the waterproof blanket should be fixed with cement nails and gaskets, and the top surface of the waterproof blanket is not allowed to be fixed with cement nails.

The length of the cement nails should not be less than 40 ram, the gasket may be round or square, the diameter or side length of the gasket should not be less than 30 ram; 500mm, 3oomm at the lap joint.

The gasket is a square gasket cut from 1.5mm thick galvanized iron sheet on site.

The side of the high-density polyethylene (HDPE) film of the waterproof blanket should face the water-facing side.

4. Waterproof blanket lap joint

The waterproof blanket is a natural lap joint, the lap joint width is 100mm, and the lap joint should be sealed with bentonite sealant, and the dosage is 0.3kg/m2. The lap joint of the large-surface waterproof blanket should not be located at the corner, and the lap joint should be more than 500 ram away from the corner; the waterproof blanket at the corner should have no additional layer.

Laying method of waterproof blanket at the corner: first lay a 500ram wide additional layer (250mm on both sides along the corner), and then lay a large surface of the waterproof blanket. Before laying the waterproof blanket on the large surface, evenly lay a layer of bentonite particles on the surface of the structure, and the dosage is 3kg/m3 .

If the overlap at the corners of the elevation and the plane is unavoidable, the overlap width should be 600lnln, that is, the waterproof blanket on the elevation and the plane should be extended 300mm to the plane and the elevation at the corners, and no additional 500ram width should be laid. The additional layer of the façade, and the waterproof blanket on the facade must be pressed on the flat waterproof blanket; if it is the outsourcing waterproofing of the roof and the corner of the side wall, the roof waterproof blanket must be pressed against the side wall waterproof blanket.

The lap width of bentonite waterproof blanket, polyurethane coating and SBS modified asphalt membrane should not be less than 400irma. The lap joints should be closely attached and flat, and no wrinkling is allowed.

On the facade, the lap joint of the waterproof blanket must be the upper and lower sheets; the splicing of the waterproof blanket should minimize the seams, and the seams should be staggered.

Lap joints must be closed with bentonite waterproofing grout.

5. End-to-end processing

The waterproof blanket laid to the top of the façade should be closed. Closing method: As shown in Figure 3, first use 30ram wide and 2mm thick galvanized iron to close the mouth, and fix the mouth with cement nails. The distance between the nails should not be greater than 300ram; the top of the waterproof blanket must be sealed with bentonite waterproof slurry.

6. Repair of damaged waterproof blanket

During the process of laying/hanging the waterproof blanket, any damage caused by nail holes or other reasons should be properly repaired.

Repair method: During the laying process of the waterproof blanket, clearly mark the damaged part first; if the damage is a nail hole, it can be sealed with bentonite waterproof slurry. For other large damages, first seal the damaged part with bentonite waterproofing slurry, and then cover and repair it with a waterproof blanket of the same quality.

7. Fine stone concrete protective layer

After the waterproof blanket is laid, a 150nm thick C20 fine stone concrete protective layer should be poured in time.

8. Precautions

During the laying process of the waterproof blanket, the early hydration of the bentonite caused by the construction water should be prevented as much as possible. Before laying waterproof blankets in open-cut construction, pay attention to weather changes in the weather forecast to prevent laying before rain and snow.

When laying the waterproof blanket at the corner of the face, first fix the waterproof blanket with nails along the corner, and then fix other parts to prevent the waterproof blanket from being hollow and tight.

In special parts such as corners, yin and yang corners, a layer of waterproof blanket should be attached as an additional layer with a width of 50omm. An additional layer should be laid first (250ram wide on both sides of the corner and the yin and yang corners), and then laid, and a large surface waterproof blanket should be hung.

3. Conclusion

In summary, the construction of bentonite waterproof blanket should do a good job in the treatment of the base layer, especially the treatment of the yin and yang corners; mastering the method of blanking during the construction process can avoid the waste of the waterproof blanket, and at the same time can reduce the construction joints; do a good job in the construction Joints and fixing are the keys to ensuring the construction quality of the waterproof blanket.