When considering innovative solutions for future challenges, it is always a good idea to look to the past as a form of inspiration and ‘due diligence’ We do it all the time when reviewing business cases that seek Tideway Innovation Forum investment (TIF).
But how far you do look? 20
years (RightWay Live has done just that to great effect), 200
years, or even 2000
?! Libby Kelly at Tideway reminded us of this when she shared this link from the BBC
with The Great Think.
Ok, I appreciate it’s dangerous for a town planner to stray into MAD territory (Tideway Materials And Durability group – led by Dave Cullen)…..but I remember when we were trialling ‘CemFree’ concrete with David Ball Group at Crossrail, and how difficult it was to achieve British Standards (BS) to satisfy designers and asset maintainers (and insurers) that this new reduced carbon material could be incorporated into into permanent works. I don’t believe we ever quite achieved this goal, mainly as the BS engineering standards state concrete must contain a percentage of ‘Ordinary Portland Cement’ (OPC)!
For those in the know, OPC (a blend of several ingredients including limestone, sandstone, ash, chalk, iron or clay) is a fantastic British invention dating to the early 1800’s which has revolutionised the construction industry as you can almost create any shape imaginable and replace it with a ‘rock’ which can also be reinforced with steel (rebar), providing structure and incredible strength for several hundreds of years. It was shortlisted for Britain’s Greatest Invention
recently on the BBC, with filming at Tideway!
As much as we love concrete (Tideway uses a lot of it!), we are mindful of the environmental impacts (it is believed to be responsible for 5% of greenhouse gas emissions during production) and it does provide long term durability challenges including surface erosion (particularly in harsh marine environments) and any present steel reinforcement can corrode if moisture and salts are allowed to seep through micro-cracks – therefore rendering structures unstable.
‘So What’? An engineering lecture from a Town Planner? No!
But with Tideway designed for a minimum 120 year operating life, we are always looking to extend the life of our asset and provide better value for investors and customers.
Looking back 2000 years to Roman marine structures (made of their own unique concrete ‘recipe’), have you ever wondered why they are still standing in harsh marine environments
when OPC wasn’t invented for another 1700 years?! Well the Romans didn’t have OPC but they did understand the engineering value of volcanic rocks.
What the Roman’s probably didn’t understand (proving again the concept that ‘to try’ is better than not too) is that in the presence of sea water, their concrete mix (which contains volcanic ash found near Rome called ‘phillipsite’) appears to gain strength from exposure to salt water as the volcanic lime content crystallises thanks to chemical reaction forming a rare mineral called ‘aluminium tobermorite’ (I’m also straying into Nick Sumption territory now). The result, Roman structures gain strength rather than weaken, it is almost like the Romans perfected self healing concrete!
This is the reason many Roman structures (sea walls, harbours) etc are still visible to this day. With access to cutting edge research (see image of high power X Rays used by University of Utah to identify the crystals), this is precisely why The Great Think and the Tideway Academic Advisory Group (TAAG) exists; to consider emerging opportunities with potential benefit to Tideway.
We are constructing miles of permanent river walls, jetties, slipways and moorings, all within a tidal river (with lots of salty water)!
Perhaps we can learn from our Roman ancestors of Londinium, not just reconnect with the river, but ‘react‘ with it!
‘scanning electron microscope showing the presence of the tobermorite within the concrete which adds strength’