If you asked people to name a vigorous, sexy, fast-growing industry, you can guarantee that 99 out of 100 wouldn't say cement. Yet we live in exciting times for the workaday material that forms so much of our built environment. On the back of a global construction boom, demand has soared in recent years - and continues to rise. 'The world cement boom continued in 2006,' notes the sober Brussels-based Cement Bureau, adding that, globally, production grew by 6% in 2005 and 12% in 2006. The first quarter of 2007 was even better, and few who know cement intimately expect any let-up before 2010. Clearly, the grey stuff is producing plenty of the green stuff.
In parallel with this, we've seen a reappraisal of concrete (a major component of which is cement) as a construction material. No longer is it a necessary evil, the stuff of '70s shopping malls and grim high-rises. Whether it's the soaring grey grandeur of places like Canary Wharf Tube station or polished concrete worktops and floors in modish apartments, architects and the public alike are starting to see concrete as beautiful in its own right.
And why not? After all, the famous dome of Rome's Pantheon - completed in AD 126 - was made of concrete. Exciting new types of concrete (of which more later) mean that its rehabilitation is likely to proceed apace.
But before we look at the reasons for cement's rise and rise, we need a bit of semantic housekeeping. Laypeople tend to use the words 'cement' and 'concrete' interchangeably, a source of irritation to those who work in the industry. Cement is the glue that holds things together. The term can refer to anything that binds materials: mud is an early, primitive cement. Nowadays, the word usually means Portland cement - a fast-setting glue made by subjecting limestone, clays and gypsum to a very high temperature (up to 1,450 degrees Centigrade) in huge kilns. Concrete is cement plus aggregates - typically sand and gravel - with admixtures and water. In some form or other, cement and concrete have been around for millennia, but the stuff that builds motorway overpasses became used widely only in the 20th century. In 2006, the world consumed 2.5 billion tonnes of cement - the only commodity humans use more of is water.
So, now we know what we're talking about, where did it all go right? It's easy to look at cranes towering over Shanghai, Mumbai and Dubai and say that a booming developing world is the reason for the good times. But the reality is slightly more complex. Certainly, a rapacious China is a big reason. It accounts for something like 50% of the world's cement consumption (and over 40% of its production). By contrast, Dubai, for all its glitz and the noise it makes, is a minnow. And although India positions itself as China's rival, it isn't in the same league when it comes to cement.
What all these markets - and places like Malaysia and South Africa - have in common is that they are growing strongly.
So far, so predictable. But what is more surprising, says Michel Rose, chief operating officer, cement, at Lafarge (world number one in cement) is how many less obvious nations are posting growth figures that most commodity industries can only dream of. 'Countries that have just joined the EU are showing tremendous growth. Poland and Romania, for example, are growing at around 20%.'
And mature economies like cement too. France may be, economically speaking, the sick man of Europe, but there's nothing wrong with its appetite for cement - up 6% on the year. Indeed, the only continent where growth has dipped a bit is North America, a result of the housing slump. But even this is from such a high that it's nothing to lose sleep over. With admirable understatement, Rose says: 'For us, the current market is quite an enjoyable place.'
Thus, a construction boom that is pretty much global makes for an industry that is working pretty much flat out. 'If I look back five or 10 years,' says Rose, 'we had five expansion programmes per year. Now, there are 15. We want to add 40 million tonnes of capacity by 2010.'
It should be noted here that when it comes to adding capacity, in this industry you need to be confident about the future. Cement plants are big pieces of infrastructure. For instance, on the India-Bangladesh border, Lafarge has a conveyor belt that transfers limestone from one country to the other, as Bangladesh has no deposits of its own. This is 17km long: journey that far from Charing Cross in central London and you're in the Surrey countryside.
Indeed, it is countries like India that are underwriting cement's medium to long-term future. In India, most cement is still sold in bags to the people who actually do the building. This means that cement is advertised as a consumer product; in most Indian cities you will see a billboard for haircare products, another for a compact car or a stereo - and another one extolling the virtues of a particular brand of cement.
Although cement is and always will be a bulk commodity - and the lion's share of sales will be in basic products - some of the highest growth rates are being achieved in advanced materials. 'If you look at innovation across the industry it comes in two forms,' says Graham Russell, VP commercial for Cemex UK, 'product innovation and service innovation.'
In the first category, he points to a product like self-compacting concrete. This does not need vibrating to remove air bubbles, saving labour and time. It has been a huge hit. Then there are high-performance concretes like Lafarge's Ductal. The addition of fibres (either steel or polymer) makes it five times stronger than normal concrete and it can actually flex; moreover, it doesn't require reinforcing rods.
Perhaps the most striking demonstration of concrete's brave new world is a footbridge in Seoul. Constructed entirely of Ductal, the bridge has a 130-metre-wide unsupported centre span. The walkway is structurally sound yet terrifyingly minimal at just 3cm thick.
The ultimate in crowd-pleasers, though, has to be translucent concrete. By placing optical fibres in the mix, it is possible to have a (rather wonderful) concrete wall that lets the light flood through.
In terms of service, Russell talks of intelligent silos that allow Cemex to know when its customers are running low on cement. This, he explains, means that all deliveries can be full loads and can be done at night when the roads are less crowded. 'The result is a surprisingly large reduction in cement miles.'
So, is it all unalloyed good news? Well, the industry has one big black mark against its name: environmental impact. For not only does cement require vast quarrying operations to produce its raw materials, it is also a big, big emitter of CO2. The problem here is that the heating process needed to convert the limestone has a double-whammy effect. Not only does cooking the rock demand large amounts of energy (often provided by burning fossil fuels) but it also drives off the carbon dioxide in the limestone itself: making one tonne of cement produces about one tonne of CO2. By way of comparison, a return flight to New York produces about 1.56 tonnes.
It's not all bad for concrete here, though. Using materials like fly ash from coal-fired power stations in the mix reduces the need for CO2-emitting limestone - and usefully recycles a waste material. There is also the question of thermal mass, says Steve Kosmatka, vice-president of research and technical development at the US-based Portland Cement Association. Buildings made of heavy materials like stone and concrete tend to need less heating and cooling, as the mass absorbs heat in the day and releases it at night. Amortised over the life of a building, this can result in a considerable CO2 saving in terms of fuel. And, he adds, new materials are improving concrete's environmental credentials in obvious areas. One new concrete even cleans the air that passes over it by absorbing pollutants; another allows rainwater to soak through, replenishing groundwater and preventing flash floods.
On the CO2 front, the industry is also taking more straightforward steps to reduce its impact. On the emissions front, Lafarge's Rose notes that his company committed itself several years ago to reduce CO2 emissions by 20% between 1990 and 2010. And the industry is also using biomass and waste products to fuel its kilns: 'I was recently in Uganda and visited a plant that is fuelled using 40% coffee husks and cotton husks. Plants can even be fired with dried sewage.'
Secondary liquid fuels are also big, according to Cemex's Russell. Cement plants can use thinners, paints and so on and 'ten million chipped tyres are burned a year across the industry' (It tells you a lot about this business that incinerating tyres is regarded as green behaviour). The cement industry has a way to go before it and the earth can claim to be friends.
But even if it's going to take a while before concrete's future is truly green, right now it is definitely rosy. The reason the industry is investing in all this new capacity is because it sees growing demand everywhere it looks. Whether it's upgrading India's 19th-century infrastructure, building 21st-century offices in Warsaw or just creating monuments to excess in Dubai, the world wants more cement.
'I've been in the industry for 37 years,' says Rose, 'and I've never been as optimistic as I am today.'
THE HARD FACTS
The only substance humans use more of than concrete (by weight) is water.
Concrete has been in use for millennia. The Romans mixed limestone with volcanic ash and aggregate and went on to build 5,300 miles of concrete roads and many buildings.
Reinforced concrete - steel rods embedded for tensile strength - was patented by Frenchman F Joseph Monier in 1867.
The US Navy built concrete ships in WWII, and it's a popular material for DIY yachts.
Although concrete sets hard within days, it continues to set, becoming slowly harder over decades. It will even set under water.
The vast US high-tech arsenal also contains cheap but effective concrete bombs - bomb casings filled with concrete. They destroy the target with their kinetic energy alone, creating very little collateral damage.
The Grand Coulee dam (opened 1942) in the US is still thought to be the largest concrete structure in the world. It contains 11.25 million cubic yards of concrete.
The average concrete mix contains only 11% cement - plus sand, aggregate and water.