Application of Bentonite Waterproof Blanket in Underground Waterproof Engineering

Anyang High-tech Development Zone Ancai Jiayuan 1 sample building project has 2 underground floors, 26 floors above ground, frame-shear structure, construction area of ​​37,229, and underground waterproof level. According to the past construction experience, the company undertaking the construction task of the project believes that the traditional waterproof materials are used in many construction procedures and the construction time is long. The exterior of the basement cannot be backfilled in time, and the safety construction scaffolding cannot be erected in time, which will bring security risks to the subsequent construction. In order to solve this problem, a QC team was formed in the preparation stage of the project construction, and the selection of waterproof materials was demonstrated. The bentonite waterproof material was used to improve and innovate the underground waterproof process, and the PDCA cycle was used in the construction, and achieved obvious results. The results have not only improved the quality of waterproof construction, shortened the construction time of underground waterproofing, but also saved about 270,000 yuan in cost.

1. Composition of bentonite waterproof material

Bentonite waterproof material refers to the underground engineering waterproof material made of natural sodium bentonite. Including bentonite waterproof blanket main material and bentonite waterproof powder, waterproof slurry and bentonite rubber waterstop and other supporting materials. Auxiliary materials include cement nails and gaskets.

Bentonite waterproof blanket is a blanket-like material knitted by two layers of geotextile (one layer of woven geotextile and one layer of non-woven geotextile) wrapped with sodium-based bentonite particles. The outer surface of the non-woven geotextile is heated with a layer of high-density poly Vinyl film. Bentonite waterproof powder and waterproof slurry are mainly used in the reinforcement treatment of the roots and inner corners of through-wall pipes and the sealing of lap joints of waterproof blankets, and the repair of damaged parts. Edge trims are used for head shake closure.

Second, the waterproof construction process and method of bentonite material

Method construction process: base surface leakage treatment, base surface treatment, waterproof blanket laying, lap joints, waterproof slurry, closing head, shaking, and edge protection, repairing damaged parts, and finished product protection.

1. Base surface treatment

The base surface of the waterproof blanket should be solid, clean and flat. The deep pits on the base surface should be smoothed with cement mortar, and the sharp protrusions should be removed. The yin and yang angles of the base surface should be made of 50x50mm obtuse angle or ~50mm rounded angle with cement mortar. The base surface is allowed to be wet, but there should be no point-like water leakage or linear water flow phenomenon; the treatment of the seepage water on the base surface should be mainly based on blocking, and when it is difficult to block, temporary drainage measures can be used.

2. Laying of waterproof blanket

The waterproof blanket cutting is based on the principle of minimizing the overlap of the waterproof blanket and saving materials. When laying bentonite waterproof blanket, cement nails and gaskets should be perforated and fixed. The length of the cement nail should not be less than 40mm, and the diameter or side length of the gasket should not be less than 30mm. The gasket material can be galvanized iron sheet (thickness above 1.5mm) or plastic sheet that meets the requirements; the cement nails should be arranged in a plum blossom shape. The spacing of the nails should be: the elevation, plane, and slope should not be more than 500mm, and the lap joint should not be more than 300mm.

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

3. Lap joint of waterproof blanket

The overlapping width of the waterproof blanket should not be less than 100mm. The lap joint should not be set at the corner, and the lap joint should be more than 500mm away from the corner; additional layers should be added to the waterproof blanket at the corner, first lay a 500 ram wide additional layer (250mm on both sides of the corner), and then lay a large surface waterproof blanket. If it is the outsourcing waterproofing of the corners of the roof and side walls, the roof waterproof blanket must be pressed against the side wall waterproof blanket. On the vertical (oblique) surface, the overlap of the waterproof blanket must be the upper web and the lower web.

The stitching of the waterproof blanket should minimize the seams, and the seams should be staggered. The lap joints should be closely attached and flat, and no wrinkling is allowed. Lap joints must be closed with bentonite waterproofing grout.

4. Head shake protection, connection and end treatment of waterproof blanket

The reserved length of the head shake should be greater than 500 ram, and it should be sealed with edge closing strips. The head impulse on the facade should be protected by a 300mm wide white iron sheet or low-density polyethylene waterproof board to prevent debris from entering the back of the head impulse or the disturbance and damage to the head impulse caused by construction. The head shake on the plane is wrapped in a U-shape with a flexible temporary protective layer, and then the temporary protective plate is pressed for protection.

When the head impulse is connected, the debris in the head impulse must be removed. Flipping butt joints must be closed with bentonite waterproofing grout. When connecting, the edge strip should be torn off first.

The waterproof blanket laid to the top of the façade should be closed. Use 30ram wide, 0.5 to 1. 00mm thick white iron sheet closed. The closure is fixed with cement nails, and the distance between the nails should not be less than 300mm. The top of the waterproof blanket must be sealed with bentonite waterproof slurry.

5. Repair of damaged waterproof blanket

During the process of laying/hanging the waterproof blanket, any damage caused by nails or other reasons should be properly repaired. If the damage is a nail hole, it can be closed with bentonite waterproof slurry. For other large damages, first seal the damaged part with bentonite waterproof slurry, and then cover it with a homogeneous waterproof blanket.

6. Detail structure waterproof construction

During the waterproof construction of the through-wall pipe,

1) First clean up the debris at the root of the wall pipe:

2) Dig holes on the waterproof blanket according to the size and shape of the through-wall pipe:

3) Before laying the waterproof blanket, the bottom wall pipe should be sprinkled with bentonite waterproof powder around the root of the pipe;

4) The waterproof blanket set on the wall-penetrating pipe should be in close contact with the base surface without wrinkles;

5) The joint between the waterproof blanket and the through-wall pipe must be closed with a bentonite waterproof slurry to an obtuse angle of 40x40mm:

6) Clean the surface of the through-wall pipe, install a bentonite rubber waterstop at the center of the through-wall pipe to stop the water. The waterproof construction principle of construction joints and deformation joints is the same as that of through-wall pipes.

3. Key points of construction quality control of bentonite material underground waterproof engineering

1) The main material and supporting materials of the waterproof blanket used should have the product factory certificate, product physical and technical performance test report, product use instructions and anti-counterfeiting signs: the construction unit should check its appearance, specifications, models and quality certification documents, etc. Acceptance and witness sampling test.

2) A special construction plan and quality assurance measures should be prepared before the construction of the bentonite material waterproofing project.

3) Each process is subject to quality control according to construction technical standards. After each process is completed, the construction unit will check and record. Handover inspection shall be carried out between processes. The previous process shall meet the construction conditions and technical requirements of the next process. The handover inspection between relevant professional processes and concealed works shall be inspected and approved by the supervising engineer before concealment, and records shall be formed.

4. Conclusion

1) Bentonite waterproof material is used for underground waterproof construction. The construction process is relatively simple, the construction period is short, no heating and pasting are required, and only nails and washers are needed to connect and fix it. If waterproof defects are found, it is easy to repair. The shortest construction period. It took only 1.5 days for the waterproof construction of the bottom plate of the 1# Building of Ancai Jiayuan. The waterproof construction of the basement exterior wall took 3 days, which was about 20 days earlier than the traditional waterproof construction of the same level.

2) Bentonite waterproof material has long-lasting waterproof performance, good compactness and guaranteed quality. After more than one year of observation, there is no leakage.

3) Due to the simple process, short construction period, saving materials and labor, it saves about 270,000 yuan compared with the traditional waterproof construction of the same level. It truly achieves technological progress, quality assurance, economical and reasonable, safe and reliable, green and environmental protection (non-toxic and harmless to human body), and is a new technology worthy of promotion and application.