Case Study: SewerCem Concrete project in Singapore

Singapore´s Deep Tunnel Sewerage System (DTSS) phase 2 is an underground “superhighway” for Singapore’s used water management. DTSS uses deep tunnels – down to 60m below the surface – to convey used water entirely by gravity to three centralized water treatment plants at coastal areas. The treated used water is then reclaimed, purified and discharged to the sea in an environmentally responsible manner.

Approximately 50 km of deep sewer tunnels with 3-6 m in diameter will be constructed by tunnel boring machines over the course of 10 years, ending in 2025. The targeted lifetime of the sewer tunnel is achieved by combining special efforts for protection of microbiological induced concrete corrosion (MIC). MIC occurs when the bacteria in the sewer hydrogen sulfide which is later transferred into sulfuric acid and damages the concrete. Click here to see the microbiological induced corrosion video. The excellent material properties of Calcium Aluminate Cement (CAC) achieve well over a 100 year of lifetime, which is simulated and confirmed by the Fraunhofer Institute (UMSICHT). Enclosed you can see the difference if no CAC was added.

*30°C, 50 ppm H2S, RN > 90 %

Calucem has developed the highly corrosion resistant SewerCem Concrete to fulfill the challenging specifications of DTSS phase 2. The rapid compressive strength development of >10 MPa after 10 hours ensures a fast demolding and ensures reliable concreting. SewerCem Concrete durability, long term strength and excellent corrosion resistance has been extensively tested and confirmed by Singaporean, Australian and German Universities.  Especially the 1-year MIC resistance tests yielded extraordinarily good results for CAC as compared to typical Portland cement based solutions. The MIC test is simulating  a minimal corrosion over a 100-year lifespan. Portland cement based concrete shows 5x higher damage depth than SewerCem Concrete.(see below figure for the comparison).

SewerCem Concrete has been approved to be used in DTSS phase 2 tunnels by the Building and Construction Authority (BCA) of Singapore after passing additional tests on long term strength development at 35°C and 50°C.

Calucem conducted a SewerCem concrete pumping test in Singapore on the 6^th of March 2021 together with our local partners. SewerCem Concrete with steel fibers in the mix design was horizontally pumped over a distance of 30m under construction site conditions. SewerCem Concrete had a high flowability and was pumpable for 3 hours, achieving >25 MPa strength after one day. Click here to see the SewerCem pump trial video.

SewerCem concrete´s nearly self-compacting behavior and high early strength development makes it an ideal concrete for easy & reliable application on site, making SewerCem a cost- and environmental saving solution for sewer tunnel construction, thus reducing the total costs of ownership.

“Calucem’s SewerCem concretes are special designed solutions able to withstand for a hundred and more years even inmost severe micro-biological induced corrosion (MIC) conditions in Sewer pipes” explains Dr. Günther Walenta, CTO of the Calucem Group.

“We love Singapore and want the best for Singapore, SewerCem is the best long-term solution and therefore a smart investment for a life time”, Yuri Bouwhuis, CEO of the Calucem Group, said.

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