Internal & External Waterstop Installation Methods and Steps

Waterstop is a waterproof product that takes advantages of high elastic deformation to achieve waterproof performance when being subject to stress. It is pre-embedded in the deformation joints and integrated with the concrete when pouring the concrete. In this way, it can effectively prevent water leakage at the deformation joints of the structure and serve as a cushion to mitigate shocks and impacts, thereby ensuring the engineering structure meets the specified waterproof requirements.

It is widely used in deformation joints or construction joints of water conservancy, hydropower, dam, culvert and sluice, tunnel, and subway, civil air defense fortifications, high-rise building basement and parking lots for waterproof.

Then how to pour concrete and install waterstops properly? As waterstops are generally divided into internal waterstops that are buried in concrete and external waterstops that are pre-embedded on the surface of the concrete, therefore, their installation method also varies. Here we’d like to introduce the installation methods of internal and external waterstops, which are applicable to both rubber and plastic waterstops. We can install waterstops in the following steps.

1. Get necessary tools and accessories prepared.

   Before installing the waterstop, we need to get steel wire, hot melt machine, hot melt knife and sealant well prepared to ensure the smooth progress of the pouring.

   Hot melt machine

   It is suitable for rubber waterstops. When the rubber waterstop needs to extend its length, a hot melt machine is required to melt the two ends of the rubber waterstops and connect them together.

   Hot melt knife

   It is suitable for plastic waterstops. When the plastic waterstop needs to extend its length, a hot melt knife is required to melt the two ends of the plastic waterstop and connect them together.

   Rubber adhesive

   When the rubber waterstop needs to extend its length, rubber adhesive is recommended for splicing and fixing of two rubber waterstops.

2. Make first-stage preparations.

   1. Clean waterstops, remove debris in the joints and dry the water on the surface of waterstops before pouring to ensure that waterstops are tightly combined with the concrete.
   2. During the pouring, horizontal deformation joint construction must be carried out first and a special-assigned person must be assigned for compaction and exhaust near the waterstop.

3. Make the waterstop extend to an appropriate length by welding.

   Waterstops are generally connected by two methods. One is the cold joint method for cold bonding with rubber adhesive, and the other is the hot joint method for welding joints with hot melt machine or hot melt knife.

   • Cold joint method

     Flatten and rough two joints, and then apply a thin layer of sealant. Apply another layer of sealant after drying. Place two joints in a predetermined position after drying for adhesion and pressurization. Pour the concrete after 30 minutes. Featured by rapid solidification, convenient construction, time and effort saving, this joint method can meet general engineering quality requirements.

   • Hot joint method

     • Hot melt machine joint method

       Hot melt machine must be equipped with a power supply and a power distribution cabinet for heating and press vulcanization. The operating procedures are relatively complex; however, the joint quality is better than cold joint. In some projects with higher construction requirements, hot joint method is specified. For more information about hot melt machine operation, please refer to rubber waterstop welding. If you are looking for hot melt machines, please contact us directly.

     • Hot melt knife joint method

       Preheat the hot melt knife first and fix the waterstop on both sides of the hot melt knife. The heat of the knife melts both sides of the waterstop. Wait for a certain period and take the knife away. Connect two waterstops together.

     Holt melt knife joint steps

4. Install the waterstop.

   • Internal waterstop installation

     In the process of concrete construction, improper positioning of internal waterstop often leads to inaccurate internal waterstop location and large deformation, resulting in poor waterproof effect and leakage. Therefore, we shall proceed as follows to ensure the correct location of internal waterstop.

     • Horizontally placed internal waterstop installation

       The surveyor shall mark the ink line on the cushion to locate the position of deformation joint. Bind the reinforcements and erect the formwork. The positioning ink line shall be exposed when the formwork erection is finished to check if the internal waterstop deviates from its original position.

       When the reinforcement binding is finished, fix both ends of the internal waterstop with positioning steel bars and flat steels. The flat steel is used to fix the internal waterstop firmly. Weld the flat steel to the reinforcement within the reinforcement mesh and the positioning steel bar. The bolts for fixing the flat steel shall be spaced at an interval of 500 mm. Make sure the center bulb of the internal waterstop coincides with the center of the deformation joint. Meanwhile, both ends of the internal waterstop shall be placed upwrap slightly and form a horizontal angle of 15° to 30° with the center bulb to facilitate the air bubbles escaping from the internal waterstop when conducting manual concrete vibration.

     • Vertically placed internal waterstop installation

       Plumbing method shall be used to ensure that the internal waterstop is perpendicular to the bottom control line.

       For the part of the internal waterstop not fixed with the formwork, concrete blocks shall be bound to the positioning steel bar at an interval of 300 mm for fixing. When fixing the internal waterstop, make sure to keep the internal waterstop flat.

       Place a 50 mm × 50 mm reinforced wooden support on both ends of the internal waterstop. For the resting part, steel formwork is erected to connect with the wooden support on both ends at an interval of 1 m to make ensure that the wooden supports are connected as a whole and clamp the internal waterstop firmly.

       When the strength of the concrete on one side of the deformation joint reaches 30% of designed strength, remove the formwork and then pour the concrete on the other side.

     Internal waterstop installation location

     Internal waterstop in concrete walls

5. External waterstop installation

   1. First identify the installation position of the external waterstop. It is generally used for the construction joints of the overall lining and placed outside the construction joints and deformation joints of lining structures. During the construction, place installation lines at the position where external waterstops are required in accordance with the design requirements.
   2. Base surface treatment. For external waterstops that are directly installed on the rock wall or the initial support leveling layer, the installation position needs to be leveled with chloroprene latex mortar in advance. The width of the waterproof mortar plastering surface shall be 20 cm greater than that of the external waterstop.
   3. During the external waterstop fixing, if the construction joint is designed with a waterproof sheet and the external waterstop and the waterproof board are made of the same materials, a double-seam hot welding machine is used to fix the waterstop on the waterproof sheet; If the external waterstop is made of rubber, cold joint methods is employed to connect the external waterstop to the waterproof sheet and fix it to the rock wall or the initial support leveling layer.
   External waterstop installation location

   External waterstop installation effect

Although the installation method of the waterstop differs as they are installed in different locations, we can install the waterstop easily and conveniently as long as we master the correct installation method. Moreover, for applications such as buildings, culverts, and water tanks, external and internal waterstops are used together when pouring the concrete. If you still wonder how to choose waterstops properly, please contact us directly, we will recommend waterstops perfect for your application.

The combination uses of external and internal waterstops

External & internal waterstop concrete pouring