LININGS - FRC | TECHNICAL


Execution drawing from the REM project, Canada.


for these approaches. Research has confirmed that the NF EN 14488-3 Method B test is particularly useful for characterising fibre-reinforced sprayed concrete. A minimum performance class of 3c can be achieved with high-performance Dramix® steel fibres, such as 4D 65/35BG. EFNARC is an international not-for-profit body helping to advance standards and skills in specialist concrete and construction systems. It latest guidance guidance on sprayed concrete panels provides best practice recommendations for preparing panels for tests, in accordance with EN 14487 and EN 14488. It covers 600mm × 600mm × 100mm-thick panels for EN 14488- 5 energy absorption tests, and EN 14488-3 Method B notched-panel tests. Also, fib Bulletin 116 indicates that residual strength values aligned with Model Code 2010 can be obtained directly from Method B. With the benefits of Dramix® fibres now proven in


tunnel segments and sprayed concrete linings, there is potential for the same principles to be extended for application in other infrastructure elements.


WIDENING APPLICATIONS Recent projects illustrate how high-performance steel fibres can support applications beyond standard tunnel linings.


REM project, Canada On the Réseau Express Métropolitain (REM) tunnel project in Montreal, Canada, FRC was used not only for precast segments and permanent SCL but also in foundations, precast divider wall panels and pipe encasement. In these applications, high-performance fibres provided


a practical alternative to traditional rebar or mesh, helping to simplify construction while maintaining the required structural performance.


West Gate Tunnel, Australia Another important example is the use of hybrid SFRC for corbels in the West Gate Tunnel project in Melbourne, Australia. The technical paper published in ATC 2023, ‘Steel Fibre Reinforced Concrete and its Application as a Load Bearing Corbel in West Gate Tunnel’, (see ref) provides detailed information about this project In early 2021, the design joint venture was asked to develop an alternative


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structural design and construction methodology because of constructability and safety concerns. Road-deck corbels were required to support the road-deck planks, while smoke-duct corbels were needed to support smoke- duct planks separating the smoke duct from the main carriageway. Following initial discussions, a hybrid solution combining steel fibres with conventional reinforcement was identified as the most feasible approach. The design was based on Model Code 2010. The crossbar


and top anchor provide Ultimate Limit State load transfer, while the longitudinal bars and steel fibres control cracking in the corbel. For Serviceability Limit State (SLS) restrained- shrinkage design, the FRC achieved fRk,1 = 4.0 MPa and fRk,3 = 3.9 MPa, exceeding a minimum 4c performance class. Compared with conventionally reinforced corbels, the


hybrid SFRC option using 35 kg/m³ of Dramix® 4D 65/35BG offered benefits in both material cost and construction programme. The solution reduced conventional steel tonnage by 38%, equivalent to approximately 825 tonnes, mainly by reducing longitudinal reinforcement that had originally been required for crack control. This reduction lowered material costs, reduced truck


and multi-service vehicle (MSV) movements, improved logistics in and out of the tunnel, reduced incident risk


Typical cross-sections of (L) tunnel, illustrating smoke duct level, road deck level, and


maintenance tunnel level; and, (R) a conventionally reinforced smoke duct corbel with bonded anchor to the segmental lining.


Conventionally reinforced smoke duct corbel versus Hybrid SFRC version.


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