John Knapton鈥榮 passion for concrete has taken him places. He helped develop a fireproof lining for the Channel Tunnel. He invented a device to stop vandals knocking over gravestones. He is tribal chief of a village in Ghana. Now Lloyd鈥檚, the insurance group, has employed him to assess the collapse of the World Trade Center. His job is to find out if the design was at fault in any way. Ian Sample asks the professor of structural engineering at Newcastle University what happened inside the towers on 11 September, and learns a thing or two about the delights of concrete.
Why did Lloyd鈥檚 choose you for the World Trade Center job?
It鈥檚 very simple: I was on the Jimmy Young Show on BBC Radio 2 talking about the collapse of the World Trade Center. I have no delusions of grandeur. You can publish any number of scientific papers in internationally refereed journals, but if you鈥檙e on the Jimmy Young Show, you鈥檙e the man.
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What is your role?
They need advice on how the buildings fell down, whether anyone else鈥檚 incompetence contributed to the collapse, and whether the buildings performed well or not.
How will you find that out?
We鈥檙e trying to get permission to visit the rubble that鈥檚 been removed from Ground Zero and is now on one of New York鈥檚 islands. We need to go quickly because once the snow comes the evidence may not be as valuable. I鈥檓 also very concerned because I am hearing that the steel columns are being melted back down and turned into scrap.
Is there anything in particular that you want to investigate?
I have seen pictures showing that some of the fireproofing material on the columns came off during the fire, which it shouldn鈥檛 have. The three external sides of the columns were sprayed with concrete and the internal side was coated with vermiculite. All the vermiculite seems to have come off in sheets, while the concrete has stayed on. If the vermiculite came off very early, that will have shortened the time it took for the buildings to collapse, which means a lot of people might have died as a result. If the fire protection had worked better, it is possible the buildings could have stayed standing. There have been major fires in other tall buildings around the world and they haven鈥檛 collapsed.
What else will you be looking for?
The buildings had these great 18-metre steel trusses spanning from the perimeter columns to the core. It was unusual to have no columns between the perimeter columns and the core. One of the things they were concerned about when they designed the buildings was the vibration from wind that might be transmitted through the exterior fa莽ade into the beams, which would then shake the people inside. So they put in a special elastic shock-absorbing system to stop the vibration being transferred down the trusses from the external columns to the floor. That could be an indication of a structural weakness, because when you prevent the transmission of forces from one element of the building to another you are taking away some of its strength.
Aren鈥檛 you really just trying to get Lloyd鈥檚 off the hook?
Not so much off the hook. They are going to pay the insurance, but they may be asking those who they deem contributed to the collapse, through their negligence or whatever, to reimburse them. Lloyd鈥檚 are liable for $3.6 billion, on which they have reinsured, and they are going to lose $1.9 billion.
How bad will that be for Lloyd鈥檚?
The strength of Lloyd鈥檚 goes back to the 1906 earthquake in San Francisco, when they were the only insurance company that paid up, so they have a tremendous reputation for that and they want to keep that reputation. In the end the World Trade Center collapse will do them no harm, because when things like this happen all it really does is extend the size of the insurance market. Everybody pays for it in the end and they will get their money back.
How long will your investigation last?
I imagine at least 10 years.
Do you think 11 September will affect how buildings are built or even where businesses are located?
It depends on who you talk to. The architects who specialise in tall buildings are saying it will make no difference at all, which is nonsense. There are people in the Sears Tower in Chicago who have left their jobs. A lot of people are very nervous about being in a tall building because they realise things can happen that could trap them. I think it was the sight of people taking that awful decision to jump. We all put ourselves in that position-do I burn to death, or do I jump? It鈥檚 been known for a long time that there is no way fire crews can fight a fire in a tall building above about 15 stories. One of the issues in the World Trade Center fire was that people were told to stay put. That is the normal advice, to stay above it until it puts itself out. They never plan to evacuate that kind of building in its entirety. Also, people were not told that while they couldn鈥檛 use the upper lifts, they could use the lower lifts.
Where does your expertise in concrete come in?
The fire protection was fundamentally concrete, and that鈥檚 an issue. The floors were concrete too and it was the weight of the concrete that killed everyone. I don鈥檛 think the steel was a major issue at all. The debate is going to be about the use of concrete.
You鈥檝e devoted your whole career to concrete. Convince me it鈥檚 an interesting material . . .
We all own some concrete. It鈥檚 the most owned material in the world, and just about the cheapest. It costs less than 拢20 a tonne. That鈥檚 because the essential ingredient in concrete is cement, the world鈥檚 cheapest glue. You can pay a few pounds for a very large bag of cement. Compare that to the price of buying UHU or Araldite, where you pay pounds for a tiny tube. It鈥檚 also fascinating from a technical viewpoint. If you break it open, it has lots of different things going on in it, all working sometimes with one another and sometimes against one another.
But isn鈥檛 concrete really about depressing grey tower blocks?
It is, and that鈥檚 one of the reasons it鈥檚 fascinating because it has been used inadvisedly in various contexts. But where it has been used appropriately, it鈥檚 made a great impact. I would argue that concrete has had more of an impact on eradicating contagious diseases than the entire domain of medical research, simply through the construction of sewers in cities. You鈥檝e got to explain to people that concrete isn鈥檛 that awful concrete jungle material. It鈥檚 actually something that is of incredible value to humanity.
Concrete鈥檚 been around for ages. Don鈥檛 you think we should have come up with something better by now?
It鈥檚 absolutely right for the job because it鈥檚 cheap. Simple as that. And the reason it鈥檚 cheap is because of the cement. It鈥檚 basically cement with dirt. I think it鈥檚 incredible that we invented it, because you have to take clay, limestone and chalk, dry them out to form a powder, mix them together and set fire to it to form an ash. Grinding that ash to dust gives you cement. How would anyone think of that?
Who did think of it?
It was invented by Joseph Aspdin from Leeds in 1824. He went through that process. He patented it, and the very first cement factory was constructed on the banks of the Tyne in Gateshead.
Did he know what he was doing?
No, he was basically fiddling about. But we鈥檝e had similar materials for thousands of years. The natural cement that for example the Romans used was simply the product of volcanoes. If you take the clinker, the ash that comes out of volcanoes, and grind it, it makes a very effective cement.
But isn鈥檛 it becoming obsolete?
Absolutely not. There are lots of things being developed to make it more useable. I鈥檓 doing research with polypropylene fibres-little short things that you get in a bedspread -that give concrete incredibly good fire protection. After the Channel Tunnel caught fire a couple of years ago, they repaired it using concrete with these polypropylene fibres. If it happens again the concrete won鈥檛 shatter, as it did the first time, which was really bad news for the firemen who went in. Quite a few were injured.
How did you get involved in gravestones?
Since the mid-1950s, graves have tended to be just a piece of granite or something that sits on a tiny rock base and sticks out of the ground. The problem is they are not very stable and can be pushed over. So we invented a gravestone anchor called the Newcastle Anchor, which is basically a corkscrew. You drive the corkscrew into the ground and a little device connects it to the base of the gravestone. It prevents people pushing it over.
Do people often push over gravestones?
Absolutely. It鈥檚 very common. Every now and then you see a newspaper headline saying vandals have gone in and knocked over 50 headstones. It鈥檚 a regional thing-Liverpool, Manchester, the north-east, Glasgow, some parts of London. It鈥檚 seasonal too-you get a lot around this time of year.
You鈥檝e been called 鈥渢he king of concrete鈥�. How did you earn that title?
It comes from another aspect of my life-I鈥檓 a chief in Ghana.
Please explain . . .
In the 1970s I had a PhD student, Kwesi Andam, from a village called Ekumfi-Atakwa in Ghana. When he went back after completing his PhD we kept in touch, and in 1993 he said he wanted to show me his village and how destitute it was. We got there and it was awful. Children were dying, no one had jobs, people were malnourished-nothing exceptional by African rural standards, but none the less desolate. Kwesi was a professor in Ghana by then and he had been trying to help in the village for a number of years. He wanted to do all sorts of things-bring in education, health, clean water. So I said OK, let鈥檚 form a team. I had in mind that we would raise a few hundred pounds. In fact, since then we have raised 拢140,000.
How did you come to be chief?
They did it simply because I had been a few times and the Ghanaians are great people. To them, someone who keeps going back is someone to be respected. I committed myself to looking after the interests of that village, whenever called upon, 24 hours a day for the rest of my life. I am now 鈥淣ana Odapagyan Ekumfi the First鈥�. And my son will take over-it鈥檚 a hereditary chiefdom.
What鈥檚 it got to do with civil engineering?
We鈥檙e basically moving the village forward with civil engineering: building a school and library, putting in a borehole, increasing the stability of the houses. The difference is that other people would be managing the work and then seeking others to carry it out. We can do it ourselves. We鈥檙e like a one-shop operation.