Building a better future for tunnelling.

Mike May, Cemex’s European Sales Manager for Mortars, discusses the growing demand for end-to-end sprayed concrete lining solutions, a recent complex refurbishment of Scotland’s Mullardoch Tunnel and the introduction of lower carbon sprayed concrete…

The demand for new sprayed concrete lining has increased dramatically in recent years with major new tunnelling projects in the airport, rail, hydro and power generation industries. Amongst this growth remains a steady flow of complex and bespoke tunnel maintenance and refurbishment programmes which are ongoing across the UK. 

Cemex is committed to providing collaborative end-to-end solutions covering many phases of the tunnelling process. Central to this is our aim to develop and offer reliable, efficient and more sustainable solutions for the tunnelling industry that are fully cogniscent of the needs of our customers and end-users. Our partnerships focus on innovation through collaboration, to capitalise on multiple areas of expertise to support each stage of the project.

Sustainable urban spaces

Tunnelling is an extremely specialist and performance-critical industry. Along with the importance of identifying the correct concrete mix and equipment, the nature of tunnelling in high-profile environments comes with its own set of unique challenges, requiring complex and well-planned solutions. 

As urban areas become more dense and open spaces increasingly unavailable, in part due to continuous population growth, tunnelling and underground infrastructure requires a more creative, yet equally robust approach, to develop the space available into sustainable urbanised landscapes. There is a growing requirement to futureproof the resilience of cities from the impact of climate change, alongside the need to reduce visual, environmental and noise impacts, by minimising disturbance to surfaces. And all of this, whilst embracing the critical need for communities to be connected through people-orientated transportation systems and infrastructure.

Lower Carbon Sprayed Concrete

Our lower carbon sprayed concrete, part of our family of Vertua products and solutions, has a carbon embodiment of 23% below our industry renowned “Bank Mix” Silo Sprayed concrete, making it an ideal solution for constructors of large-scale tunnelling projects where the necessity to develop new infrastructure needs to be balanced against the environmental impact.  The Cemex Specialist Solutions Lower Carbon Sprayed Concrete is only the first step in our ambitious aim to supply the tunnelling industry with more sustainable products. The introduction of our lower carbon sprayed concrete as our core product achieves the first phase objective. Our next aim is to produce a sprayed concrete with a target carbon embodiment reduction of up to 40%.

The Vertua lower carbon product symbol is awarded to selected cement and other products characterised by their unique raw material composition, which contains the highest quality ingredients to reduce the carbon footprint of the finished product.

Mullardoch Tunnel Restoration

Cemex recently provided a special, high-performance blend of Dry Sprayed Concrete with reinforced steel fibres, to assist in the complex and successful restoration of the Mullardoch Tunnel project, in the Scottish Highlands.

The Mullardoch Tunnel, running from Tomich to Cannich, is located approximately 25 miles south-west of Inverness. It provides access to the hydro-electric scheme at Fasnakyle Power Station which was initially built in the 1950’s as part of the North of Scotland Hydro-Electric Board's drive to provide electricity for northern Scotland. The tunnel was constructed by drill and blast methods through the rock which at the time of construction was a highly ambitious build, providing stable access routes through the remote and mountainous valley.

As part of the ongoing tunnel management and maintenance inspections, a defective area of rock was identified in 2019 which needed large-scale repair. A collapse inside the tunnel would pose major operational issues for the nearby power station, with far reaching effects. A programme of repair was required to stabilise the tunnel using rock bolts and finished off with a bespoke high performance blend of reinforced dry sprayed concrete.

The advanced Cemex lining product was proposed by sprayed concrete specialist Gunform International Limited and formulated in close partnership with Cemex. The material was supplied in 1000kg bags and installed using a big bag dispenser and Reed LOVA Gunite Machine. The Cemex material, with an internal accelerator, was applied in thickness up to 500mm thick to create a regular hard-wearing finish. The main contractor for the Mullardoch Tunnel project was AMCO-Giffen Ltd and the client was SSE plc (formerly Scottish and Southern Energy plc).

Access to the tunnel site at Mullardoch was extremely restricted which posed additional challenges. It was imperative for Cemex to meet the demands on site and the project completed on time. Cemex’s high performance fibre reinforced concrete offers bespoke design solutions incorporating a 3-Dimensional system of either macro-synthetic or steel fibre reinforcement, which reduces the risk of cracking, increases impact and shatter resistance, improves surface durability and reduces long-term maintenance costs. At Mullardoch, the Dry Spray Concrete product arrived on site each time with the fibres evenly distributed throughout the product, allowing the time-saving process of placing concrete and reinforcement in a single operation.

Cemex’s tailor made fibre reinforced concrete is produced to suit specific customer needs and manufactured in accordance with BS EN ISO 9001, BES 6001 and BS EN 14889. It is independently certified under the Quality Scheme for Ready Mixed Concrete (QSRMC) in accordance with the relevant standards and is available from Cemex plants throughout the UK.

Specialist Technical Support

In addition to sprayed concrete primary lining solutions, Cemex has extensive experience in designing, producing, and delivering concrete across all tunnelling related structures. The company has proficient experience and capability in providing sprayed lining solutions and  can produce both cast in-situ or sprayed concrete products delivered in a pre-blended dry silo.

All specialist technical support and laboratory testing is performed by a Cemex team of UKAS accredited technical experts providing comprehensive solutions for all testing requirements, from approval to continuous compliance and investigations. Our centrally located facility enables nationwide site testing, and is backed by wider specialist resources and technical expertise from our global Cemex business.

For more information www.cemex.co.uk