Mapei ‘strengthening’ Mui Trau twin tunnels

The new La Son-Tuy Loan Expressway in Vietnam, featuring 77.5 km long, is a link between Thua Thien-Hue Province and Da Nang City. When fully operational, the road would play a fundamental role in the economic and social development of the two regions. 

With four lanes of traffic, the new expressway connects La Son Town in the Phu Loc District of Thua Thien-Hue Province and the intersection with the Da Nang-Quang Ngai Expressway in Da Nang’s Tuy Loan Village. The project forms part of the 3,000-km Ho Chi Minh Highway that passes through 28 towns and cities. 

Construction work on the La Son-Tuy Loan Expressway is being carried out by local contractors, Song Da 10 and Son Hai Group. It commenced in 2015, including various tunnels along the route. Among them are the Mui Trau twin tunnels in the Hoa Vang District, which are believed to be one of the most modern road tunnels ever built in Vietnam. Both tunnels are 2,260 m in total length, 10.8 m wide and 7.2m high, providing two lanes of traffic.

Strengthening the concrete structure

In this project, Mapei was commissioned to supply its admixtures to enhance the quality of the concrete used for the tunnels. The company provided the Mapequick AFK 888 accelerator along with the Mapefluid N 100 SP, Dynamon Easy 11 and Dynamon SR2 VN superplasticisers.

The Mapequick AFK 888 is an alkali-free, inorganic salt-based liquid accelerator for producing shotcrete characterised by rapid setting times and a quick development of its strength. Concrete mixed with this system can adhere better to surfaces on which it is applied, offers a higher capacity to penetrate between the various layers and reduces waste.

The Mapefluid N 100 SP is a liquid superplasticising admixture for quality concrete (watertight, durable and high-strength). Due to the high workability obtained without excess water in the mix, concrete with Mapefluid N 100 SP admixture is easy to place while fresh and has high performance characteristics when hardened. This system is mainly used for ready-mix concrete, pumped concrete and mass concrete.

The combination of Easy 11 and SR2 VN represents a new and innovative improvement in concrete admixture technology, compared to the use of just one admixture in a traditional concrete mix.

The Mapequick AFK 888 and Mapefluid N 100 SP systems were used to produce shotcrete, which was sprayed on the tunnel walls. The Dynamon Easy 11 and Dynamon SR2 VN systems were applied on the tunnel linings. In total, the four products covered an area of 2,260 m long. Mapei was involved in the project from 2015 to 2019.

(The article courtesy of Realta Mapei International no. 83)