Projects | 13. September 2023 ZIM project study proves potential of thermoset gap-filling material MM1018 in pre-stressed bolted joints

Mönchengladbach, 13.09.2023 – In steel construction, bolted joints are prestressed for reasons of load-bearing capacity or serviceability. Gap formations caused by production or assembly are a risk for applying the required pretensioning force level and promote the development of crevice corrosion. A possible, environmentally compatible alternative to gap compensation with lining plates was investigated as part of the ZIM cooperation project “Bri-San-T – DuroFüllSta”: the Liquid Lining Plate® MM1018. The sliding factor tests carried out as part of the two-year study show encouraging potential with regard to possible use in slip-resistant prestressed joints. A sufficiently high strength of the material is already achieved after 24 hours.

Manufacturing and assembly-related imperfections cannot be ruled out in steel construction, so gaps can form between the bolted components of bridges, radio masts or tower structures. These gaps can significantly impair the permanent load-bearing capacity of the prestressed bolted connection and even lead to premature failure. They must therefore be kept to a minimum according to EN 1090-2.

Since gaps often cannot be fully compensated by stiffeners, the ZIM cooperation project “Bri-San-T – DuroFüllSta” dealt with the development of environmentally compatible, gap-compensating materials that connect the gaps positively and non-positively and can be used in prestressed bolted connections of steel construction.

The project, which was funded by the BMWK, was carried out by the Institute for Metal and Lightweight Construction at the University of Essen in cooperation with DIAMANT Polymer GmbH. For the first time, both the pretensioning force losses and the sliding resistance were analyzed and taken into account in the development of a design concept. Different, environmentally compatible materials were used in the formulation of the gap compensation materials.

The metal polymer MM1018 investigated in the project is a two-component reaction resin system filled with special metallic materials, which can be supplied in both liquid (MM1018 FL) and paste consistency (MM1018 P). The applicability of the metal polymer has been proven by the general building authority approval (abZ Z-3 82-2042) in Germany and has already proven itself thousands of times in practice.

The sliding factor tests carried out in experimental investigations in accordance with EN 1090- 2, Annex G, showed encouraging potential with regard to the possible use of Liquid Lining Sheet® MM1018 in slip-resistant prestressed joints. A further investigation showed that a high strength of the material is already achieved after 24 hours.

With the experimental investigations carried out, a fundamental basis for the future conception of the slip-resistant prestressed connection using the MM1018 FL and MM1018 P gap fillers was created in terms of dimensioning and design.

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