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Where there's muck there's chemistry

Prof John Bensted

When was the Construction Materials Group formed?
It was formed back in 1933, exactly 75 years ago this month, although it started life as the Road and Building Materials Group. The name changed back in the 1980s to better reflect what is going on in the sector.

What areas does the Group cover?
Essentially, the Group can be subdivided into sections: the black top side – asphalt and bitumen – and the white top side, which to the layperson is cement and concrete.

What are the hot topics in this sector?
Green issues are one of the most topical issues in the sector at the moment. For the black top side, dealing with the negative effects of run-off water into the environment from newly constructed or repaired roads is a top priority. For the white top side, a key priority is using more industrial by-product materials like slag, fly ash and microsilica with Portland cement to produce ‘extended cements’. These improve the overall cementing performance and lower energy costs substantially, thus ‘killing two birds with one stone’.

What advances have been made in the sector since the 1930s?
It is important to note that the black and white top materials go back a long time. Bitumen oozing out of the ground was used in ancient Mesopotamia as a binder in construction. Gypsum plaster dating from around 9000 BC in Asia Minor was used as a base for frescoes, and a lime-based concrete floor discovered beside the Sea of Galilee dates from around 7000 BC.

Since the 1930s, the main advances on the black top side have been in improving safety. For example, replacing bitumen surface dressings on roads with more durable thin-layer bituminous surfaces. Skid resistance has been markedly improved with the newer surfaces and with vehicular traffic using specially formulated skid-resistant tyres. Issues of dealing with run-off water from roads are being increasingly addressed.

On the white top side the main advances have been the developments and uses of more speciality cements for specific purposes, along with the extended cements already mentioned. For example, cement employed for roads or buildings is different from that used in mining, tunnelling or garden ornaments, as is the consistency, water content and strength attained by the concrete during construction.

But by far the most important development has been the growth of science-based knowledge, as opposed to a culture of experimentation, particularly in the asphalt and bitumen sector, which, until recently, had developed without much study of the chemicals involved.

Many people think of the sector as just a lot of ‘muck and dirt’ – is there any truth in this?
This is a highly technical area, which is based on expert scientific knowledge; although it is an area that is sadly neglected and does not attract enough interest from the younger generation. But it is an essential science and one that we should be looking to nurture. Otherwise, we will be overtaken by international companies who will pick up the knowledge where we have left off, taking with them the wealth generation, innovation and knowledge that goes with any intellectual property leaving the UK.

How do modern construction materials and standards compare to those of the past, for example, the Victorian era – can you say there was a golden age of construction?
If there was a golden era, then we have to go much farther back than the Victorians. If anything, the Romans encapsulated a ‘golden era’. Around 13BC, Marcus Vitruvius Pollo published his Latin ten-volume De Architectura. It was the first standard of its kind, describing cement making and building techniques – the results of Roman architecture speak for themselves.

Unfortunately, the techniques declined with the overall decline of the Roman Empire. Surprisingly, a book appeared in the mid-13th century when Bartholemaeus Anglicus (an Englishman) published in Latin De Proprietatibus Rerum (On the properties of things). It was translated into Middle English by John Trevisa in 1397. It was widely used and led to improvements in cement (lime) quality and standards of workmanship for about 50 years. However, these improvements didn’t last and standards deteriorated until the 18th century, when the Industrial Revolution got underway. Then, the art of making good quality cement was rediscovered. The rest, as they say, is history!

What events has the Group organised recently?
We had a number of events in 2008. On 15 October 2008, the ‘Pathology of 20th century buildings’ looked at interesting and radical changes in construction, components and materials, which after the Second World War, saw the introduction of listed buildings and the development of conservation areas. In October 2008 we focused on ‘Road drainage and the environment’, looking at rising water levels due to climate change and the devastating consequences of flooding on our transport system, motorways and other roads, and why it is more more important than ever that we are able to respond as an industry to meet the demands of an effective road pavement drainage system. In November 2008 there was a seminar on ‘Recent developments in roofing’ which looked at green living roofs and thermal insulation technology.

Construction Materials Group

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