The center of Emmen has undergone a major transformation. The central Hondsrugweg has been tunneled, and above it, a vibrant central square of over 26,000 m2 has been created. The size is comparable to about four football fields. Additionally, the Emmen Zoo has been relocated from the east to the west side, an extensive project with the new name Wildlands Adventure Zoo. The long double tunnel, measuring an impressive 235 meters, ensures that traffic can pass underneath the new square.
6,000m2 protective coating of sprayed concrete at Hondsrugtunnel in Emmen
Methodology and advantages of the CSM technique
The four tunnel walls were constructed using the CSM (Cutter Soil Mix) technique. A cutter loosens the sand and loam soil and mixes it with a grout mixture. This is done panel by panel, always leaving a temporary space in between to prevent the soil from collapsing. After mixing, steel profiles are placed in the wall as reinforcement. To shorten the construction time, three cutting machines were used to work on four walls simultaneously. The beauty of this technique, compared to a diaphragm wall, is
- No large bentonite plant is required;
- No soil and bentonite need to be removed;
- No concrete needs to be supplied.
This technique has also been applied in, among others, the parking garage on Westerstraat in Emmen, where SealteQ executed the synthetic floor finishing.
Solution against Crumbling Flakes and Crack Formation
After it became clear that the walls of the brand-new tunnel were suffering from crumbling flakes and crack formation, contractor BAM decided to have SealteQ apply a protective layer of 6,000 m² of shotcrete. For this purpose, Remix Droge Mortel BV from Borger developed a special mortar in the same color as the “old” tunnel wall.
SealteQ applied a network of fiberglass to the existing substrate. This was anchored using special Hilti Anchors. Afterwards, SealteQ finished the walls with a 35 mm layer of shotcrete, using the ‘wet spray method’. The “rock wall-like” appearance has thus been preserved.