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October 2023

Safe sealing of conical tie holes with

STOPPER SCREW

Dear Sir or Madam,

Formwork systems that use conical tie rods instead of classic distance tubes are becoming increasingly important in concrete construction throughout Europe. The permanent, pressurized water-tight sealing of the resulting conical tie holes in the concrete component presents a particular challenge.

Both the conical course of the tie holes as well as the wall surface of the tie points must be taken into account. Therefore, in addition to the existing tests for pressurized water tightness, we have had our STOPPER SCREW system tested by MFPA Leipzig for this particular application as well.

The test was carried out on the Peri MX 15 and MX 18 formwork system as a representative of conical tie systems. The pitch of the cone course in the test was as follows:

Peri MX 15: 18,4 mm to 22,3 mm

Peri MX 18: 24,3 mm to 27,6 mm

Both specimens successfully passed the 28-day pressurized water test at 5 bar water pressure, i.e. without water penetration.

Another factor that should be considered with conical tie systems is the surface quality of the inner surface of the tie hole. The time of removal of the tie and the care taken at compaction around the tie rod during concreting will affect the surface. Insufficient care may result in grooves and shrinkage cavities.

The rubber of the STOPPER SCREW system, which expands when tightened, provides the appropriate solution. The TPE compound works its way into the smallest cavities of the concrete surface and seals reliably and permanently.

Perfect sealing of formwork tie points and tie holes

Expands when screw is tightened

Installation independent of weather conditions

For fibre cement and plastic distance tubes as well as conical tie systems

Low space requirement for storage

Further tests

Water

Fire

■ Fire resistance class EI 240 according to DIN EN 13501-2 Room closure test with fibre cement distance tubes No cracks or gaps to the test room occur within the test duration of 240 minutes. During this time, no flames were visible on the side facing away from the fire.

■ Construction material class DIN EN 13501-1 E = normally flammable DIN 4102-1 B2 = normally flammable

Sound

Standard sound level differential test

MFPA test according to DIN EN ISO 10140-2

A distance tube installed in concrete and sealed at both ends with the STOPPER SCREW achieves exactly the same standard sound level as monolithic concrete with the same component thickness.

Radon

A distance tube built into concrete, which was sealed on both sides with the STOPPER SCREW, reliably prevents radon from entering.

STOPPER SCREW from MASTERTEC is designed for distance tubes and tie holes with an inner diameter from 17 to 34 mm. It is available as “in” and “covered” version, which enable the visually neat sealing of distance tubes with lip as well as cone.