Concrete Admixture for High-Speed Railway

Background

The Shangqiu-Hefei-Hangzhou High-Speed Railway, also known as the "Second East China Corridor," is a high-speed rail line connecting Shangqiu in Henan Province, Hefei in Anhui Province, and Hangzhou in Zhejiang Province. The Huai River Grand Bridge on the Shangqiu-Hefei-Hangzhou High-Speed Railway is approximately 17 kilometers long, with a main span of 228 meters, and at the time of construction, it held the world record for the largest span of a high-speed railway bridge with ballastless track. After the completion of the Huai River Grand Bridge, trains will pass over the Huai River at a speed of 350 kilometers per hour, taking only a few seconds, which means the bridge will bear a huge impact force. This poses extremely high requirements for the construction quality of the project. 

Project challenge

The on-site construction used the Type III slab track technology without ballast, which requires concrete with a low slump of 80mm to 140mm and a slump loss of no more than 20mm within 2 hours. 

Background

Shanghai high-speed railway along Yangtze river is an important part of the main channel of high-speed railway along the river of the national“eight vertical and eight horizontal”high-speed railway network, and it is also the first national mainline high-speed railway passing through Taizhou, and the Taizhou section of the line is about 52 kilometres long, with Taizhou South Station and Huangqiao Station as two stations. Located in Taixing City Fenjie Town, one Chinese Railway  Bureau has constructed the Taizhou section of the high-speed railway along Yangtze river with a total length of about 28.5 kilometres, of which the Taizhou section of the station 9 standard has a length of 19.8 kilometres, and the bridge substructure such as bridges, pile foundations, bearing platforms and piers has already come to an end.

Fig. 1 Schematic diagram of the site

Project challenge

The issue of appearance of bubble and workability. The concrete prepared on site had poor workability, and severe segregation was likely to occur after adding water. Moreover, the fluidity of the concrete did not change significantly after increasing the dosage of admixtures. After pouring and vibrating during construction, the concrete surface had a thick layer of laitance, and after demolding, the surface of the components had a dense distribution of pinhole-type bubbles, posing a risk of cracking.

 Fig. 2 Schematic diagram of the appearance of the protective wall