Wood you believe it?

Oh dear, the New Scientist is the latest publication to fall under the spell of ‘timber can save the
world’ mantra by replacing the evil that is concrete (The New Age of Wood, 16th March 2019).

The article argues that we live in the “hydrocarbon age” which makes possible the materials that ‘define our
civilisation: steel, concrete and plastic’. It goes on to claim that “everything that is made from fossil-based materials today, can be made from a tree tomorrow’. While some examples are obvious, e.g. timber buildings, others require new technologies. Apparently, a timber ‘tougher and stronger’ than
high performance steel can be made from soft wood. Obviously, it must be processed first, which involves ‘chemically removing half of the lignin then brutally compressing what is left at high temperature’. No mention is made of how much carbon is emitted in this process. I wonder what
solution they will claim can replace concrete paving or asphalt roads. Perhaps they’ll transform
timber decking into something that can survive being run over by all the articulated lorries that will
be needed to haul all that imported timber and timber products around the country. Better hope it doesn’t rain, it might get a bit slippery!

I have rehearsed the arguments about the carbon content of concrete before and how it is a victim
of its own success and talked about the disadvantages of CLT, e.g. the poor acoustic qualities that required a school to ban pupils from talking in the corridors and the peeling layers that
means it can add fuel to a fire.

Let’s consider some of the other issues that get glossed over.
Where are you going to put all these trees? Has anybody worked out how many trees would need
to be planted to replace all concrete, steel and plastic and would there be any land left over to
provide food for the world’s growing population or house them?
Apparently, one cubic metre of timber stores one tonne of CO2, which contrasts positively to
cement where one tonne of cement creates getting on for one tonne of CO2. However, concrete is a
low carbon material because not much cement is used in its production (and that cement is often partly replaced
by low CO2 products like slag and fly ash). What happens at the end of life? The timber will
probably be burnt to produce energy also known as releasing all that stored CO2 back into the
atmosphere. So, when the New Scientist claim “switching to timber would immediately wipe a
billion tonnes off global carbon emissions”, what they fail to add is that in 50-100 years time much of
it will still end up in the atmosphere. Concrete by contrast, reabsorbs CO2 throughout its life by a
process of carbonation. At the end of its life, if it is crushed up to produce recycled aggregate, the
increase in surface area of the particles will accelerate the carbonation, increasing the amount of
reabsorbed CO2.
Don’t get me wrong, I’m not saying don’t use timber, or develop new technologies. What I am
saying is that concrete is a wonderfully adaptable, durable, cheap and locally available product. Let’s
look at ways to improve further the sustainability of concrete, e.g. by sequestration of CO2, rather
than trying to create a concrete-free fantasy land.

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Gooseberries can fly

On to the third and final leg of my trip in bullish mood after some positive meetings with colleagues in Abu Dhabi and Dubai but still feeling the effects of my Bangladesh food poisoning. Over the last two years, when I’ve mentioned I’m visiting Bangladesh I don’t think a single person has offered to take my place or looked at me enviously and expressed a wish that they could come with me.
But that has all changed with my latest venture. I’ve had so many offers to carry my bags that if I’d accepted them all I wouldn’t have needed any suitcases, I could just give everybody a single item of clothing to carry. I mean, what is it about the Maldives that makes you all go weak -at-the-knees with envy?

Is it the fact it’s 32 degrees Celsius?
Or is it the soft white sands?
Or maybe the crystal-clear blue water?

Make no mistake, this is not a holiday, we are here to work. Judging by the plane I flew in on, I’m in a minority of one. The plane was full of couples: old couples, young newlyweds and couples of every shape size, colour and sexual orientation in between. All kissing, cuddling and whispering in anticipation and excitement of their romantic break. Oh, and me, the world’s biggest gooseberry, third wheel or whatever your preferred phrase is. I didn’t even have my colleague with me as we had gone our separate ways over t he weekend and planned to meet up in Male.

We are here for the first stage of a new project funded by the Asian Development Bank looking to divert construction and demolition waste and the residue from Municipal Waste Incinerators from landfill to more productive purposes. So, while the aforementioned couples dreamily headed off to those beautiful islands, the highlight of my day was visiting the capital’s waste transfer station.

Tomorrow we catch a ferry in the morning and head off to one of those neighbouring islands, Thilafushi, also known as the waste island. Maybe it’s the attraction of a large landfill site at 32°C that appeals to you or is it that nobody mentions Brexit?

THE SPY WHO LOVED ceMEnt

I’ve arrived in Dubai on the next leg of what my son calls my mini Gap Year. The change of view from my Bangladesh Hotel to my Dubai Hotel is welcome.

Room with no view (Dhaka)

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Room with a view (Dubai)

Somebody once told me that during the cold war British spies operated under cover as cement salesman. The fact that cement goes everywhere in the world apparently offered the perfect cover for their clandestine activities. I don’t know if this is true, but I rather like the thought of a smooth talking cement salesman suggesting your concrete should be “shaken not stirred”. I tried googling to see if I could find any evidence and I did find some interesting facts that suggest it might not be a million miles from the truth.

For example the connection is made by Lord Selborne, who was Director of Cement in the Ministry of Works during WWII and left this role to become Minister of Economic Warfare, which put him in political control of the Special Operations Executive, the organisation responsible for organising clandestine activities in occupied Europe. Atlantic Wall, a musical based on a true storey about the French Resistance has a character, Henri Giraud, an ex- First World War artillery officer, recruited to develop a fledgling spy network in Normandy. He uses his job as a cement salesman – which allows him to travel freely between Paris and his home town Caen – as cover for his intelligence work.

Why this interest in espionage and cement? Well it’s partly to add a bit of glamour and excitement to the “grey” world I work in and partly to put into context the second part of this post. I’m taking the opportunity of being in the UAE, to promote the activities of the small part of Mott MacDonald I belong to. While our, Bridges, Tunnels, Ports, Coastal and Offshore operations have no problem selling their skills – “they do what it says on the tin” as the advert goes, our function is not so clear.

I work for Special Services! Our team has nothing to do with clandestine operations (although I would say that wouldn’t I) but we are the repository that ends up with projects that nobody else wants to and/or can deal with. We were formed when alkali-silica reaction was dominating the concrete world back in the mid-1980s and there was a belief that they needed to bring together structural and materials expertise to address the problem. We’ve developed a wide-range of skills over the ensuing years as problems have come our way.

Some of our areas of expertise are shown below. Do not hesitate to contact me if you’d like to find out more about any of these special services we provide.

I apologise if you can’t get the image of me wielding a Schmidt Hammer with a licence to kill out of your mind. In that case I’m just glad I didn’t mention the other kind of special services that are offered by certain kinds of ladies in the personal ads of your local newspaper. Oh dear, too late!

List of some of our Special Services

  • Dynamic Analysis,
  • Forensic engineering,
  • Slab track analysis and design,
  • Human induced vibration,
  • Durability modelling and design,
  • Cathodic protection,
  • Wind engineering,
  • Blast analysis and design,
  • Noise and vibration measurement, analysis and mitigation,
  • Short-circuit analysis
  • Fire analysis
  • Fatigue analysis
  • Aerodynamics,
  • Finite element modelling
  • Seismic design of structures
  • Non-linear buckling analysis
  • Analysis of masonry vaulted structures,
  • Flood containing retaining walls,
  • Expert witness
  • Alkali-activated slags
  • Stress corrosion cracking,
  • Welding investigations,
  • FRP design
  • Tribology,
  • Through life asset management,

Training the trainers

This week I have been delivering a “training the trainers” workshop to engineers from the Local Government Engineering Depatment (LGED) in Bangladesh. We have been explaining the findings of our research looking to improve the climate resilience of their structures in the coastal regions and hopefully equipping them to cascade the knowledge through their regions. Our schedule has completely gone out of the window because of the level of engagement of the audience.

In a previous existence when I worked for the Concrete Centre, I used to undertake a lot of CPD training sessions with UK engineers. While you would usually get a couple of questions at the end from somebody who was keen, the overwhelming feeling was that most were only there for the free sandwiches. That’s certainly not the case in Bangladesh.

Every session has had massive levels of audience interaction. We’ve been challenged (in a positive way) about our conclusions and there has been huge debates with us and between themselves. I really wish I could speak Bangla so I could follow the discussion rather than having to rely on the edited highlights from our local colleagues who have helped facilitate the workshops.

The only downside is that I’ve had to miss today’s session in which the engineers are presenting on how they will improve concrete durability in their regions. To spare the squeamish I shall use the euphemism that I’ve eaten something that hasn’t agreed with me. In my last post I marvelled at how modern technology allowed me to post from an aeroplane at 36000ft above Mosul; you don’t want to know what’s happening while I post this!

Modern technology

The wonders of modern technology are allowing me to post this message from somewhere near Mosul, well 36994ft above it actually. I’m heading to Bangladesh for the final stage of a DfID funded project we’ve been working on for a couple of years in which we’re trying to improve the durability of their concrete in the coastal regions.

It’s been quite an interesting challenge as the country has very little in the way of natural resources (most coarse aggregate and cement is imported) except clay so they make a lot of bricks and crush them up to use as aggregate.

There is a strong belief that stronger is better and that supplementary cementitious materials are bad – a view we’ve tried to change by introducing durability testing like the Nordtest NTBuild492. My colleague Sudarshan Srinivasan presented the a paper at the durability conference in Leeds last year which summarised the work (and won 2nd best paper award). If you’re interested I can let you have a copy.

Now all we have to figure out is how to get the technology to be able to stop the chap sitting next to me from waking me up so he could go to the toilet after I’d eventually fallen to sleep!

What has limestone ever done for us?

It is strange that in an article condemning the so called “destructive impact of concrete”, the Guardian choses to illustrate it with the image of a limestone quarry rather than a cement factory or a concrete plant.

Is it because the modern production facilities do not present the negative image they are looking for?

Hope cement works

I mean apart from being a key ingredient in cement and the building blocks of many outstanding structures, why do we create this dust and scar the landscape?

According to the great (but not infallible) source, Wikipedia, limestone also has the following uses:

  • It is the raw material for the manufacture of quicklime (calcium oxide) and slaked lime (calcium hydroxide).
  • Pulverized limestone is used as a soil conditioner to neutralize acidic soils (agricultural lime).
  • It is the raw material for the manufacture of quicklime (calcium oxide) and slaked lime (calcium hydroxide).
  • Pulverized limestone is used as a soil conditioner to neutralize acidic soils (agricultural lime).
  • As a reagent in flue-gas desulfurization (it reacts with sulfur dioxide for air pollution control).
  • Glass making, in some circumstances, uses limestone.
  • It is added to toothpaste, paper, plastics, paint, tiles, and other materials as both white pigment and a cheap filler.
  • It can suppress methane explosions in underground coal mines.
  • Purified, it is added to bread and cereals as a source of calcium.
  • Calcium levels in livestock feed are supplemented with it
  • It can be used for remineralizing and increasing the alkalinity of purified water to prevent pipe corrosion and to restore essential nutrient levels.
  • Used in blast furnaces, limestone binds with silica and other impurities to remove them from the iron.
  • It is used in sculptures because of its suitability for carving.

I am sure you could come up with a lot more.

How do I sleep at night?

That was the question asked of me by a colleague, followed by a clicking sound as his tongue was extracted from his cheek, where it had been firmly planted. He had just read the Guardian article “Concrete – the most destructive material on earth”. The piece was a literary assault on the ubiquitous construction material written with such venom (even by the standard of that newspaper, which often has a very myopic view of the world) that had it been written about an individual rather than a defenceless material, libel lawyers around the land would be rubbing their hands in anticipation of the fat fees they would earn.

I must be a Carbon Criminal in the eyes of the Guardian, having spent my whole career working in different parts of the Concrete Industry. Concrete is blamed for everything from supporting corrupt governments to causing global warming or supporting organised crime. I have been toying with the idea of a blog on concrete for sometime and this article has been the catalyst I needed. It looks like the Guardian is going to have a sustained attack on concrete as they are promoting Guardian concrete week which will investigate the “shocking impact” the material has on the modern world”

It’s true that cement is an energy intensive material to produce and often bandied about is the statistic that each tonne of CEM I (aka ordinary Portland cement) generates one tonne of carbon dioxide during its production (the figure is actually less than that). But let’s not forget cement is not concrete; the two words often get mixed up and used incorrectly. The Guardian article falls into this trap when it talks about digging a hole and filling it with cement, but they are not alone.

Dan Brown got it wrong so many times in the Da Vinci Code sequel Angels and Demons that it spoilt the book for me. It was not a “huge cement bulwark thick enough to ward off attacks even by tanks”; it was concrete. And Ian MacMillan, who wrote in Neither Nowt Nor Summat, that his “Uncle Charlie and his son Little Charlie made sure they drew their initials in the cement when they built their new garage in the back garden of 34 North Street in 1963”. Uncle Charlie and his son little Charlie either wrote their initials in the concrete floor or the mortar between the bricks in the wall. They almost certainly didn’t write it in the cement (a fine grey powder that’s used to make concrete and mortar) and if they did it would have been blown away with the first gust of wind. This is simply WRONG and is equivalent to Mary Berry eulogizing about a delicate carrot flour with a scrumptious flavour on The Great British Bake Off? Flour is a powder used to make cakes; cement is a powder used to produce concrete.

The fact is that not very much cement is used in concrete, the rest of the materials (aggregate, water, admixtures and supplementary cementitious materials like ground granulated blastfurnace slag and fly ash) are typically extremely low carbon materials, so that a tonne of concrete of the type often used in foundations can have an embodied carbon dioxide content well below 100kg per tonne rather than 1000kg.

As the article points out, concrete is the second most widely consumed material in the world (after water). It can be aesthetically beautiful, it can be ugly. The fact is that without concrete our health and education would be poorer. In fact without concrete, we wouldn’t have the transport infrastructure allowing those papers to be distributed or the journalists to get to work, or the office blocks they work in, or the buildings to house the printing presses, or the shops to sell the papers in, or the electricity to run their laptops or, or, or…. (the list is endless) but in short, there would be no Guardian newspaper.

Coal, oil and gas produce more CO2 than concrete (but are used in much lower volumes), concrete has much lower CO2 content on a weight by weight basis than steel, asphalt and plasterboard. Concrete is a low carbon material and it is a victim of its own success. It is widely used because it is durable and cheap.

The article is light on suggested alternatives to concrete. Cross laminated timber is one suggestion. Obviously not suited for most of the applications that concrete is put to, it can be used for the walls of buildings. I am a governor of a school in west London, that despite my best efforts, was built in CLT. It looks attractive but there’s one big problem. The noise! CLT, unlike concrete, does not absorb noise and it was impossible to use the classrooms when there was any chatter in the corridors as pupils moved between classrooms. By necessity, the school had to implement a silence in the corridors policy.

Concrete also has inherent fire resistance unlike timber. The CLT industry has argued that you do not need to worry about fire in CLT buldings, because when they start to burn, the timber chars, effectively producing an inflammable surface on the CLT. While this may be true for solid timber, CLT is built up in layers and recent work has shown that the layers can peel providing additional fuel for the fire. In the post-Grenfell era, do we really want to promote timber housing with question marks over its safety?

Don’t get me wrong, I think the cement industry could still make giant leaps at improving the sustainability of its product. CO2 sequestration is one area to be more seriously addressed but the concrete industry is already doing a lot of good work. The UK concrete industry diverts over five million tonnes of material from external waste streams and uses them in place of primary materials. In 2014 it used 107 times more waste than it sent to landfill.

Despite the Guardian’s outpouring on concrete, to quote one of their other bête noire’s, the late Lady Thatcher,

“There is no alternative”