Readymix concrete
Technical collaboration with Align JV for readymix concrete
Chalfont Lane Compound Zero, Rickmansworth
Client
HS2
Contractor
Align JV
Location type
Train station
Completion
February 2019
The challenge
All permanent works concrete to be used on the HS2 project has to obtain client approval prior to supplies commencing onsite. It was therefore important to mobilise our technical team quickly following our award as preferred supplier for the C1 section. Mixes needed to be developed as they were to be used in a number of challenging applications including; tunnel segment production, D-Walls, piling and infrastructure works.
Our solution
Our dedicated Project Manager coordinated our approach to the technical approvals, providing a main point of contact for Align and being available at their offices. Our technical experts worked closely with the Align Materials Engineers to explore mix design and constituent materials in more detail, including the use of steel fibres in concrete. Our experts were able to build on their experience and knowledge from other major schemes to ensure we met specification requirements.
Results and benefits
Along with the segment mix we have jointly developed a further 35 HS2 approved mixes with Align, and now have an agreed technical and commercial process in place where new mixes can be added. In addition, we have also been working with other HS2 Main Works Contractors and currently have over 100 approved mixes for use on the project, with a variety of raw materials packages. Our work so far on HS2 and our understanding of the materials approval process will enable us to efficiently move through a similar process with SCS and manage resource effectively.
Additional info
Mix trials
The most complicated mix developed was the steel fibre reinforced tunnel segment mix, which accounted for almost 50% of the overall concrete volume. We worked alongside the Align design team to understand the detailed specification and we jointly developed a plan to prove the mix design, firstly in the laboratory and then in full scale production. The customer and our key supply chain worked collaboratively with the Tarmac technical team at our National laboratory in Shawell. Shortlisted mixes were trialled in bulk production at Tarmac’s pre-cast facility, Tallington. Several tunnel segments were manufactured for strength and factory acceptance testing along with a number of panels for fire testing at the Building Research Establishment (BRE).
Through early engagement and working closely together over a number of months, HS2, Align, Tarmac and our supply chain ensured a mix was developed which met the needs of the project in the most cost-effective manner.
Customer feedback
John McEvoy – Materials Engineer, ALIGN JV “From bid through to delivery Tarmac have delivered a consistent approach in their technical capability. They had clearly demonstrated that they understood our requirements and how they would deliver this on the project. Moving into the mobilisation phase, relationships were quickly established between teams with alignment of key project delivery goals. This has resulted in our teams working together to develop concrete mix designs which meet the HS2 specification, whilst reduce risk and minimise cost in an open and transparent way.”
Overview
In July 2017, the Align joint venture was awarded the C1 package of the UK High Speed 2 line (HS2). C1 consists of;
3.37km
viaduct
21.6km
of high speed rail infrastructure in a rural environment
16.04km
twin-bored tunnel
5 vent shafts
handling both intervention and tunnel ventilation facilities
Tarmac were awarded preferred concrete supplier status in February 2019 to deliver 820,000m³ of concrete across three onsite batching plants.
