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Duct Sealing with BT innovation

Ducts are an essential part of the sewer networks that supply utilities such as gas, water, electricity, ventilation and even telecommunication, and disposes off sewage from buildings, factories and communities. After all, pipes almost always lead to manholes and sewers at one point or another. In addition, there are numerous entrance and maintenance shafts at underground facilities or to sewer systems that facilitate in inspection, cleaning or restoration. Even the aeration aspect of the wastewater on its way to the treatment plant is important.


BT sealants are ideal for this purpose:

  • Repairing structural defects and leaks in the sewers and manholes
  • Reliable sealing for both existing and new duct systems

This ensures that ducts can be sealed both rapidly and with ease using products from BT innovation.

BT solutions for reliable duct sealing

In order to be able to safely seal the piping systems against underground water or leaking sewage right at the beginning of the construction process, planning should be carried out with care. It is also possible to repair sealings in critical areas. For new construction and repair, B.T. innovation provides various products that simplify sealing.

Causes for leaks

Many ducts and channels are made of precast concrete or reinforced concrete and consist of frame culverts. Smaller ducts usually contain a manhole base, manhole rings and a manhole cover. Channels and manholes are exposed to movements in the subsoil, subsidence, frost, road traffic, root damage or chemical corrosion by sewage.

Especially daily stresses such as traffic loads and aggressive wastewater cause ducts to become damaged or leaky over the course of time. This can lead to damaged concrete and sealing, such as surface damage, corrosion, cracking or leaky joints. Therefore, these structures must be regularly inspected, maintained and renovated.

RubberElast® - joint tape for waterproofing new channels and ducts

The sealing of new channels and ducts can already be carried out during the assembly of the frame culverts and concrete elements with RubberElast® and the B.T. Turnbuckle®. Concrete rings can be sealed simply with RubberElast® during assembly, while all other deep foundation structures can be additionally sealed or renovated with InnoElast® type 2.

RubberElast® joint tape is easy and quick to apply without any additional equipment. For manhole rings, the self-adhesive tape is placed on the clean contact surface. A second manhole ring is placed on top - Installation is complete. The weight of the upper ring compresses the RubberElast® and permanently seals the joint. Installation, sealing and filling are thus made possible in one day.

Advantages of RubberElast®:

  • Easy installation process
  • Waterproof immediately after installation
  • Can be used at temperatures as low as -10°C
  • Waterproof up to 5m underwater
  • Sewage, acid, alkali and salt resistant


RubberElast® can be applied quickly and without extra tools. It is self-adhesive and is glued to the contact surface of a component. The precast components are then mounted and the RubberElast® is compressed so that the component joint is sealed. The joint is instantly waterproof after compression. The material remains permanently elastic and thus seals the joints durably. Installation should be carried out in temperature ranging from -10 °C to +40 °C. RubberElast® retains its elasticity even at low temperatures.

Instructions: How to use RubberElast®

Step 1.


Position precast concrete component on worksurface

Step 2.

Apply RubberElast® to the component to be sealed (the surface must be free of dirt, grease and oil).

Step 3.

Align the second concrete component to the first and place it on top. Press the two parts together so that RubberElast® is 80% compressed.

InnoElast® - Retrofitting ducts with sealant

Existing underground structures can be sealed or renovated with InnoElast® Type 2. When sealing frame culverts and shafts with InnoElast® Type 2, it is important to remove dirt and grease residues from the concrete and to ensure a load-bearing surface on which the sealing material can adhere well. The pasty InnoElast® Type 2 is sprayed into the joint for sealing, where it hardens into a rubber-like material, thus sealing the joint.

Sealing the maintenance / inspection shaft

Inspection chambers, also called manholes, must be maintained regularly and, if necessary, serviced with InnoElast® Type 2. They are part of the municipal wastewater management system. On a private property, these manholes represent important access points within the given property boundary, through which various pipes coming from the house are connected to bridge differences in height and align the direction of the flow to the local connection of the sewer system.

Advantages of InnoElast®:

  • Solvent-free and low shrinkage
  • Can be used on damp surfaces up to -3°C
  • Weather and UV resistant, high resistance to chemicals
  • Durable elasticity
  • Up to 10% motion absorption
  • Can be used without primer
  • Can handle water pressure up to 0.48 bar


InnoElast Type 2 comes in a tubular bag, applied on to a clean surface with a spray gun and cured well. The ‘skin formation’ time is between 2 to 3 hours (type 1) and 15 minutes (type 2) at a temperature of 23°C and 50% humidity. The curing time is 3mm in 24 hours. A primer is not necessary for this process; however, it is recommended to insert a backfill cord and tape the edges. Pressing and levelling creates a firm bond with the joint edges.

Instructions: How to use InnoElast®

Step 1.


Cut open the top of the tubular bag with a pair of scissors or pliers. In addition, clean the surface (the joint).

Step 2.


Insert the bag into the spray gun and close the cap tightly.

Step 3.


Fill the joint with InnoElast® type 1 or type 2.
Optional: Insert backfill cord.


Step 4.


Protect the joint from moisture and allow to cure for at least 24 hours.


Our tips and tricks

It is important to check the root cause of leaks and other problems that may show up in the pipelines before repair. It is recommended to clean the shafts thoroughly with a high-pressure cleaner. If the shafts are damaged due to ingrown roots, you must remove the roots to prevent the reoccurrence of such damage. For a detailed description of the application of the products RubberElast® and InnoElast® Type 2, please refer to the technical data sheets.

RubberElast® and InnoElast® Type 2 are durable elastic sealants. Both are characterized by their high resistance, for example in the sewage sector. Mounting plates or mortar edgings can be used to support heavy weights, for example, in manholes sealed with RubberElast® that bear traffic loads.