Ed. Züblin AG replaced early-age cube testing with real-time in-situ strength monitoring on Contract T-07 of PUB's Deep Tunnel Sewerage System Phase 2 — 12km of MIC-resistant tunnel lining in Singapore.
Ed. Züblin AG (STRABAG SE) was awarded Contract T-07 of PUB's Deep Tunnel Sewerage System Phase 2: design and construction of 12km of deep sewer tunnels in Singapore, including multiple shaft types and drill-and-blast excavation through hard rock.
The lining required Microbiologically Influenced Corrosion (MIC) resistant concrete plus a High-Density Polyethylene (HDPE) protective layer to withstand the aggressive sewer environment.
MIC-resistant concrete reached approximately 50°C in-place due to pour volume and mass. Companion cubes cured at ambient temperature dissipated this heat, producing strength results that didn't reflect actual in-situ conditions — forcing conservative formwork hold times.
Each ring was cast in two halves. Before proceeding to the second half, the team needed confidence the first half had set — an additional conservative window without in-situ data. Over 12km of ring pours, these delays compound.
The mix was calibrated for the strength–maturity relationship, SmartHub sensors were fixed inside the formwork at each ring pour, and temperature and maturity-based strength data streamed to the ConcreteAI dashboard in real time. This data was used alongside rebound hammer testing for two independent confirmations before each formwork decision.
Knowing the 3 MPa threshold was reached in 5 hours — not 8 — let the team strip formwork and cast the second half ring with precision. The 3-hour saving per ring, compounded over hundreds of pours, advanced the programme by 2 months. Eliminating off-site cube transport and early-age destructive testing delivered 10× savings on that component of QA.
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