MC’s concrete know-how in demand for Nui Vung Tunnel

The construction of the motorway from Cam Lâm to Vinh Hao, east of Ho Chi Minh City (formerly Saigon), is a sub-project of the North-South Motorway Project in Vietnam and of national importance. The three-lane Nui Vung Tunnel, which has been driven through the rock of Nui Vung Mountain since 2021 with a planned length of more than 2.2 km and a width of 14 m, is an important component of this major national project. It will be Vietnam's fourth largest road tunnel in the future.

The technical demands on the concrete were very high, especially against the background of the hot temperatures in this region. Long-lasting liquefaction and a stable consistency of the concrete during transport and placement, as well as good slump behaviour and high early strengths, had to be ensured in order to meet the tight schedule. The client, a consortium established for infrastructure projects under the umbrella of the Vietnamese DEO CA GROUP, appointed A2Z Consulting from Hanoi as planner. The latter consulted concrete technologists from MC-BIFI Bauchemie JSC to obtain the best possible solutions for concrete placement in extreme heat and dry wind.

Use in extremely hot weather

MC-PowerFlow 2252 high-performance superplasticiser was used for the concrete applied in bored piles, pier bases, abutments, wing walls, cross beams and floor slabs. Despite the difficult weather conditions on site with high temperatures of over 35 °C and dry winds, the superplasticiser ensured long-lasting liquefaction and good consistency for up to four hours, while also delivering high early strength. For the shotcrete for the tunnel walls, the highly effective superplasticiser MC-PowerFlow 2257R was used, which not only offers above-average water savings, but also long-lasting liquefaction of up to three hours and high early strength values after 3 and 7 days. In order to additionally increase the adhesion of the shotcrete to the surfaces of the tunnel walls and to ensure the rebound of the shotcrete remained below 10 %, an alkali-free setting accelerator, MC-Shotcrete SH100, was used.

MC-TechniFlow 1102 superplasticiser was added to the hydraulic binder to consolidate the crushed rock base course and significantly extend its setting time for good compaction. As a result, it was possible to achieve a significantly higher compressive strength than specified in the tender.