Rail bridge repair project
Armavir - Russia
The three-bay Efremovskij rail bridge is a heavily used transport link serving the city of Armavir (southern Russia). For 20 years, no repair work had been done on it, leaving the structure so dilapidated that rehabilitation had become imperative. The planning consultants and applicators decided in favour of proven MC systems for the job.
External environmental influences, dynamic traffic loads and a lack of running repairs had led to numerous incidences of spalling and fracturing of the concrete components that made up the Efremovskij rail bridge. At some points, even the reinforcing steel of the supporting piers was showing signs of corrosion. In addition, both the road surface and the expansion joints had damage that needed rehabilitation. Plasto-elastic joints had formed which had become ever larger with time and were causing progressive destruction of the structural fabric. Given the generally unsound condition of the bridge, the planning institute ZAO Stroyprojekt from St Petersburg was finally entrusted with preparation of a repair and refurbishment concept, for which work the specialist applicator Doroga was commissioned.
An additional challenge existed in the fact that the bridge was regularly subjected to heavy vibration caused by the trains passing underneath and the traffic travelling across it. Because a high-tension cable for the trains ran under the bridge, there was also only a very tight time window for carrying out the repair work; this could only be performed while there were no trains running and the lines were switched off. To repair the areas under the rail bridge, therefore, the planning consultants opted for MC’s PCC replacement concrete product Nafufill KM 250 – highly suited to applications on dynamically loaded overhead and vertical structures. Both support piers and the road undercourse were repaired with this product. Nafufill KM 250 also has the advantage that it can be applied at layer thicknesses of up to 30 mm without the need for additional formwork.
Nafutekt Plus for road expansion joints
The rehabilitation concept also included the repair and sealing of the expansion joints. It was decided that this should be done using the Nafutekt Plus system, also from MC-Bauchemie – a tried, tested and approved expansion joint solution involving the use of asphalt for the permanent sealing of load-bearing joints on bridges, and one that also meets the high requirements specified in the German asphalt expansion joint standard ZTV-BEL-FÜ.
Among other things, the system comprises a polymer-modified bitumen which is poured into the gap using the “hot-in-hot” process together with high-grade chippings. This produces a permanently flexible yet highly loadable joint fill offering high density and seal integrity. The joint also becomes quickly trafficable – after just approx. five to six hours. The system is characterised by tyre-to-road friction coefficients similar to that of the road surface, offers a significant reduction in noise emission compared to conventional jointing systems, increases travel comfort and also improves driving safety.
Throughout the duration of the project, the specialist advisors from MC provided technical support to the applicator on site, helping to solve problems as they arose. The applicator also received comprehensive training to ensure professional implementation of the product system.