March’s Federation of Piling Specialists (PFS) Early Careers Group (ECG) event, held virtually 25th March 2021, was once again extremely educational and informative, with Matt Smith, Operations Leader at Expanded Geotechnical and current mentor on the Ground Forum mentoring scheme, presenting the engaging topic of “Rotary Bored Piling & Piles under Support Fluid”.

The event was also well attended with representations from Expanded, Murphy, Keltbray, Keller, Roger Bullivant, Bachy Soletanche, Bauer Tech, BAM Ritchies, Cementation Skanska, Balfour Beatty, Byland Engineering, FK Lowry, and Pile Design, as well as an individual from Volker Ground Engineering.

After the opening introductions new ECG Chair and Vice Chair, Julia Hill of Roger Bullivant and Laylee Eftekhar of Bauer Technologies, respectively were welcomed and I was thanked for my work with the group as out-going Chair.
Matt began the presentation with an overview of his career, which began back in 1998 setting out piles for Roger Bullivant, before explaining how this gave him the necessary grounding after university. He talked to the group about his love for his job and the reasons he does it and encouraged ECG members to recognise this in their own careers.

The formal part of the webinar started with an explanation about rotary bored piling and how it is one of the oldest forms of piling in use, before moving onto support fluids, and the three main types used in the UK:

• Water
• Bentonite
• Polymer

Matt then moved on to discuss the characteristics of Bentonite and Polymer, with Bentonite explored first in more detail. ‘Filter cake’ was then explained and how, if not managed, it can reduce shaft capacity, which is a consideration when bentonite is incorporated into the bore methodology.

Equipment and Bentonite plant configuration was then discussed to allow members to understand what is required to successfully use this support fluid.

The presentation then moved onto Polymer and how in the UK we commonly use ‘long chain’ Polymers for bored piling and how Polymer can manage the cuttings within the bore, rather than through a support fluid plant, with this being one of the key differences between the support fluid types.

The differences between Bentonite and Polymer, and the fact that both may be suitable on a site and options should always be considered, were then discussed, before Matt brought the presentation to a close encouraging member to ask questions on site as to why individual pieces of equipment were being used, as this would help them understand tooling and equipment choices made to deliver a project. Matt also stressed that we must ensure we all understand a client’s requirements when developing piling solutions.

A recording of the ECG meeting will be available shortly and those who would like a copy should contact fps@fps.org.uk