APPLICATION OF HIGH-PERFORMANCE CONCRETE ON CONTRACT C708 OF SINGAPORE'S NORTH-EAST MRT LINE
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Published:2002
C K Nmai, P Broome, P C Robery, 2002. "APPLICATION OF HIGH-PERFORMANCE CONCRETE ON CONTRACT C708 OF SINGAPORE'S NORTH-EAST MRT LINE", Challenges of Concrete Construction: Volume 6, Concrete for Extreme Conditions: Proceedings of the International Conference held at the University of Dundee, Scotland, UK on 9–11 September 2002, Ravindra K. Dhir, Michael J. McCarthy, Moray D. Newlands
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In early 1996, the Singapore Government announced its decision to expand the country's mass rapid transit (MRT) system by building the North-East Line from the World Trade Centre in the south of the island to the new towns of Hougang, Sengkang and Punggol in the north-eastern part of Singapore. The £2.55bn North-East Line is approximately 20 km long and is built primarily underground using precast tunnel-lining segments. Contract C708 of this project included a stretch of bored tunnel passing through bacterially active marine clays and underneath the Singapore River, possibly the worst soil and groundwater conditions to be found in Singapore. The specification requirements for the project referred to a 100-year design life and included the use of high-performance concrete with a maximum water-cementitious material ratio of 0.45 and a minimum 28-day compressive strength of 60 MPa for the concrete used in the precast tunnel segments. In addition, the specification included the use of high yield bars with a fused epoxy coating to mitigate corrosion of the reinforcing steel due to chlorides in the groundwater. At the request of the contractor, the specifying agency accepted the use of a dense silica-fume concrete and integral waterproofing corrosion inhibitor as an alternative to the epoxy-coated bar. Over 8,000 precast, high-performance concrete tunnel-lining segments were produced for the construction of the underground tunnels, which were completed in December 2000. This paper summarises the development of the high-performance concrete mixes for the tunnel lining segments, production issues and QA/QC measures that were implemented to ensure compliance with the specification.
INTRODUCTION
DESIGN CONSIDERATIONS & SPECIFICATION REQUIREMENTS
DESIGN MODIFICATIONS TO ENHANCE DURABILITY
DEVELOPMENT OF HIGH PERFORMANCE CONCRETE MIXES
PRODUCTION OF TUNNEL LININGS / QUALITY CONTROL OF HPC
CONCLUSIONS
ACKNOWLEDGEMENT
REFERENCES
