Gripping stuff: load cells and grout
Load cells are remarkably versatile, and whilst we love our moon launch stories, we also highlight some of the less glamorous yet vital roles they play.
Take, for example, grouting. Not something to get overexcited about, but grout failure can be a real problem.
Trains, tunnels and grouting
Structural damage to shield tunnel segmental linings in urban rail transit tunnels could be a disaster. According to a paper published in ‘Nature’ by a joint Chinese and Australian team (3);
“The primary causes of segment damage to include ground settlement and segment uplift caused by uneven simultaneous grouting, poor assembly quality, material aging, and environmental erosion.”
When a project was proposed to reinforce the grouting, the team needed to fully investigate the potential benefits on the load-bearing performance of the tunnel linings, both before and after reinforcement.
“To systematically investigate the mechanical recovery mechanism of damaged segments through grouting reinforcement, a full-scale, two-point symmetrical loading test was conducted in accordance with GB/T 50152-2012. … The experimental loading system, illustrated in Fig. 6, comprises a fixed-end constraint, a free end, a distribution beam, rigid shims, an electro-hydraulic servo actuator, and a load cell.”
Grouting lessons from CrossRail
Grout is often found under plates for mounting load cells, to ensure a level flat surface. The engineers putting in the piles for the Farrington Crossrail western ticket hall station faced a challenging mix of layers of clay and sand. As a result,
“The piling works involved of base grouting all 26 piles, of which 15 were permanently lined, and undertaking a bi-directional load test utilising Osterberg load cells (O Cell).” (4)
Then main differences between the O Cell test and a static load test included bi-directional loading and potential re-use the load cell so the test can be stopped and restarted if required.
In her paper, (4) Kirstie Broadbent, Cementation Skanska concluded that:
“The greatest lesson from the Osterberg cell test at Farringdon is that the shaft resistance above the cell should be considered when determining which pile should be designated as the test pile. This is to ensure there is sufficient capacity. …. It is also worth noting that the Osterberg cell test could possibly be re-used and therefore it should be considered whether, within the industry, going forward we should be considering their installation for ongoing monitoring of as-built pile capacity over time and whether this may permit increased pile re-use as cities like London become more and more developed.”
Look to the heavens
It’s not just rail tunnels with grouting issues. Perched high above the nave in Westminster Abbey on a temporary platform, restorers found that work carried out in the 1960s on the stonework was failing. As this BBC video shows (2), lumps of cement mortar could easily come loose.
Whilst not a major problem in itself to the viability of the structure, it could be a major issue if a piece fell 100 feet down onto a person in the Abbey. Rest assured the restoration includes replacing this with a lime-based mix to prevent this happening. (3) (No load cells involved in the restoration as far as we know, but we just thought it was interesting!)
Load cells and testing
Our load cells are used to test a vast range of products, structures and materials, both in testing machines and on site. We’re always happy to help with advice on the best methods, and for cost-effective replacements for aging load cells. If you have a testing challenge:
About the author
Chris Beasley is Director of Richmond Industries Ltd, designers and manufacturers of advanced load cells and force transducers for industry, governments and universities all over the world.
SOURCES:
(1) Westminster Abbey. (2024, June 13). Nave ceiling repairs reveal spectacular views. https://www.westminster-abbey.org/abbey-news/nave-ceiling-repairs-reveal-spectacular-views
(2) BBC. (2025, May 22). Repairs under way at Westminster Abbey [Video]. BBC iPlayer. https://www.bbc.co.uk/iplayer/episode/l00586xs/repairs-under-way-at-westminster-abbey
(3) Liu, S., Gao, J., & Zhang, Y. (2025). Title of the specific nature article. Scientific Reports, 15(1), Article 1234. https://doi.org/10.1038/s41598-025-19104-5
(4) Ground Engineering. (2015, December 21). Crossrail lessons: Base grouting, Osterberg cell test and the use of fibre optics in large diameter rotary bored piles. GE Plus. https://www.geplus.co.uk/technical-paper/crossrail-lessons-base-grouting-osterberg-cell-test-and-the-use-of-fibre-optics-in-large-diameter-rotary-bored-piles-21-12-2015/
