DONGTING LAKE BRIDGE ON THE INNER MONGOLIA-JIANGXI RAILWAY

Dongting Lake Bridge is located at the edge of a large fault zone. Complicated geological conditions present great challenges to construction and high-grade concrete is required. Sika polycarboxylic acid high-performance water reducer and high-performance retarder satisfiy the construction requirements. The Dongting Lake Bridge is the first heavy load railway bridge spanning an internal Lake in China.

Dongting Lake Bridge on the Inner Mongolia-Jiangxi Railway
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Three-tower cable-stayed railway bridge

The Dongting Lake Bridge on the Inner Mongolia-Jiangxi Railway, is a cable-stayed railway bridge in Yueyang City, Hunan Province, China. It crosses the Xiang River where it meets Dongting Lake and the Yangtze River. It is approximately 4.2 km from the upstream Dongting Lake Bridge and approximately 2.2 km from the downstream Lianhua hydrologic station. It is one of the key control projects of the Inner Mongolia-Jiangxi Railway. This two-track heavy load cable-stayed railway bridge with three towers has a girder structure combining steel boxes and steel trusses and a main span of 1,290.24 m. It has a load bearing capacity of 10,000 tons and can support heavy haul trains running at up to 120 km/h. Its main truss spans 14 m and can resist once-in-a-century flooding and magnitude 7 earthquakes.

Thebridge is unprecedented in the world as the three-tower cable-stayed railway bridge with the largest span; the firstcable-stayed bridge with a main frame combining steel boxes and steel trusses; and the first to adopt a scheme that setup and closed the steel box framework before installing the steel trusses. It is also the first Chinese railway bridge to apply long reinforced cables from the middle tower.

High-performance water reducer guarantees concrete durability
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High-performance water reducer guarantees concrete durability

Dongting Lake Bridge is located at the edge of a large fault zone, with a rock gradient at the fault ranging from 70° to 90°, which is almost vertical to sea level. Complicated geological conditions present great challenges to construction, and high-grade concrete is required. Due to volatile road conditions and changeable weather, the slump loss should not be more than 2 cm within1-3 hours and the slump loss should not rise. In certain locations such as the concrete-filled steel tube, slump must be retained for up to 5 hours. The concrete should also retain high strength and be resistant to cracking despite the high temperature differential between day and night. 

The contractor applied Sikaplast® 1220 polycarboxylicacid high-performance water reducer, which guarantees concrete durability. As 4,000 m3 of concrete had to be poured in a single continuous process during the construction of the tower base, the concrete had to solidify in no less than 48 hours. This was achieved through the use of Sika high-performance retarder Retrado l 25. During construction, continuous optimization was carried out to cater for changes to the materials, changes in weather conditions and adjustments to construction techniques.