Durable Solutions for Metro Expansion

Once completed, the MRT Orange Line will play a key role in Bangkok’s urban transport system. The mass rail transit system is divided into western and eastern branches, and will stretch for almost 40 kilometers when complete. The western section is still in the planning phase, whereas the eastern section of the “Thailand Cultural Center - Min Buri” MRT Orange Line will be up and running in 2023. It was conceived as both an underground and overground rail system, with a total length of some 23 kilometers. The MRT Orange Line project is the largest project in Thailand for Sika to date, including 10 underground and 7 overground stations, 11 ventilation and intervention shafts, a depot, and a Park & Ride facility. More than 80 innovative products from the Sika portfolio were used in the construction of the underground stations and the ventilation and intervention shafts.
 

The first underground line to be part of the Bangkok mass rail transport system, the Blue Line, was built about 25 years ago. At that time, Sika Thailand supplied concrete admixtures, waterproofing sealant between precast concrete segments, and several repair products like mortars and grouts. As part of the expansion of Bangkok’s mass rail transit network, construction of the Orange Line began in 2017. Sika Thailand has continuously expanded its product portfolio to meet the diverse customer requirements in underground metro projects as well as in the construction of utility tunnels. Aside from the challenges that tunneling projects normally face, there were a number of additional difficulties in Thailand’s capital, including the construction of the two 6.3-meter wide underground tubes. The city’s subsoil is very soft, composed of three different loam soils with different geological characteristics. Every tunnel in Bangkok therefore has to be bored with an Earth Pressure Balance Tunnel Boring Machine (EPB-TBM). The earth pressure balance (EPB) approach is a mechanical process that supports the driving site through the use of the excavation material. However, this material needs to be stabilized to ensure a safe and successful process, which in turn requires special products such as foams. Therefore, Sika brought two innovative products as a solution: Sika® Stabilizer-1118 TBM TH and Sika® Stabilizer- 1518 TBM TH. These are liquid foaming agents based on biodegradable anionic surfactants. Using these TBM products for the first time was crucial to the tunnel’s success. During the previous project, the Blue Line, Sika’s contribution was limited to concrete products, repair and waterproofing products. Kanokwan Chuanak, Head of Key Project Management at Sika Thailand, stresses the importance of this technological leap.

Bangkok is a tropical city, and construction sites are exposed to significant climate stresses, particularly during the rainy season. This was a challenge that became apparent early on in the construction phase. Thanks to the availability of new innovative products the experts were able to face this challenge. “For the waterproofing of the station roofs, we processed Sikalastic®-680 AP. If it rains heavily during processing, work has to be suspended,” explains Kanokwan Chuanak. This occurred on multiple occasions. “But with this product’s efficiency of application, construction operations were always completed to deadline even in challenging construction phases such as these. Sikalastic®-680 AP is easy to apply and dries quickly, which was good for our scheduling.” Around 260 tons of Sika liquid applied waterproofing membrane were used over the course of the project. Among the new products supplied, SikaFuko® reinjectable injection hose and SikaSwell® S-2, a hydrophilic swellable joint sealant, were used in combination with Sika Waterbar®- Omega Type at the connection between tunnels and stations. In addition, Sika was the preferred supplier for the waterproofing sealant between precast concrete segments. More than 500 kilometers of the Sika® Hydrotite hydrophilic waterstop strips have been delivered. Sika was also supplying Sika® Sigunit® L-53 TH, an alkali-free shotcrete accelerator that was used to accelerate the sprayed concrete used in small tunnels linking the main tunnels of the metro line and the ventilation and intervention shafts.

Sika has been established in Thailand since 1989, where it has an outstanding reputation for providing quality technical support on construction projects. This is due to the highly competent local team, as Kanokwan Chuanak observed: “Our technical specialists gain experience from every new project. In the Concrete team, for example, our specialists spend plenty of time on the job site in order to advise on the ideal mix design. We also have technicians who demonstrate how our products should best be applied. This is an important factor in the success of a project.” Sika established a special department for key projects at the start of its project development activity. The expertise acquired in this department is of great importance. Sika has developed a comprehensive product spectrum for all phases of tunneling projects.

According to Kanokwan Chuanak, this is an investment in the future. “With this complete offering, we’ve been able to serve a number of other projects and developers in the tunneling area.” About 5,000 kilometers of tunnel are built worldwide every year, which yields enormous opportunities for Sika.