Concrete: a material of construction & destruction - and how to fix it

How often is it that we fail to consider what is under our noses? One of the most ubiquitous of man-made artifices - at least to the 55% of us who live in urban environments - is concrete. Our high-rise cities and power stations, farmyard siloes and hydroelectric dams wouldn't exist without it. As it is, global concrete consumption has quadrupled over the past quarter century, making it second only to water in terms of humanity's most-consumed substance. Unfortunately, it is also one of most environmentally-unfriendly materials on the planet.

Apart from what you might consider to be the aesthetic crimes of the bland, cookie-cutter approach to International Modernist architecture, there is a far greater issue due to the environmental degradation caused by the concrete manufacturing process. Cement is a key component of the material, but generates around 8% of all carbon dioxide emissions worldwide. As such, there needs to be a 20% reduction over the next ten years in order to fulfil the Paris Agreement - yet there is thought there may be a 25% increase in demand for concrete during this time span, particularly from the developing world. Although lower-carbon cements are being developed, concrete production causes other environmental issues as well. In particular, sand and gravel extraction is bad for the local ecology, including catastrophic damage to the sea bed.

So are there any alternatives? Since the 1990's, television series such as Grand Designs have presented British, New Zealand and Australian-based projects for (at times) extremely sustainable houses made from materials such as shipping containers, driftwood, straw bales, even shredded newspaper. However, these are mostly the unique dream builds of entrepreneurs, visionaries and let's face it, latter-day hippies. The techniques used might be suitable for domestic architecture, but they are impractical at a larger scale.

The US firm bioMASON studied coral in order to develop an alternative to conventional bricks, which generate large amounts of greenhouse gases during the firing process. They use a biomineralisation process, which basically consists of injecting microbes into nutrient-rich water containing sand and watching the rod-shaped bacteria grow into bricks over three to five days.  It's still comparatively early days for the technology, so meanwhile, what about applying the three environmental ‘Rs' of Reduce, Reuse and Recycle to conventional concrete design and manufacturing?

1 Reduce

3D printers are starting to be used in the construction industry to fabricate building and structural components, even small footbridges. Concrete extrusion designs require less material than is required by conventional timber moulds - not to mention removing the need for the timber itself. One common technique is to build up shapes such as walls from thin, stacked, layers. The technology is time-effective too: walls can be built up at a rate of several metres per hour, which may induce companies to make the initial outlay for the printing machinery.

As an example of the low cost, a 35 square metre demonstration house was built in Austin, Texas, last year at a cost of US$10,000 - and it only took 2 days to build. This year may see an entire housing project built in the Netherlands using 3D-printed concrete. Another technique has been pioneered at Exeter University in the UK, using graphene as an additive to reduce the amount of concrete required. This greatly increases both the water resistance and strength compared to the conventional material, thus halving the material requirement.

2 Reuse

Less than a third of the material from conventionally-built brick and timber structures can be reused after demolition. The post-war construction industry has continually reduced the quality of the building material it uses, especially in the residential sector; think of pre-fabricated roof trusses, made of new growth, comparatively unseasoned timber and held together by perforated connector plates. The intended lifespan of such structures could be as little as sixty years, with some integrated components such as roofing failing much sooner.

Compare this to Roman structures such as aqueducts and the Pantheon (the latter still being the world's largest unreinforced concrete dome) which are sound after two millennia, thanks to their volcanic ash-rich material and sophisticated engineering. Surely it makes sense to use concrete to construct long-lasting structures, rather than buildings that will not last as long as their architects? If the reuse of contemporary construction materials is minimal (about as far removed as you can get from the traditional approach of robbing out stone-based structures in their entirety) then longevity is the most logical alternative.

3 Recycle

It is becoming possible to both recycle other waste into concrete-based building materials and use concrete itself as a secure storage for greenhouse gases. A Canadian company called CarbonCure has developed a technique for permanently sequestering carbon dioxide in their concrete by converting it into a mineral during the manufacturing process, with the added benefits of increasing the strength of the material while reducing the amount of cement required.

As for recycling waste material as an ingredient, companies around the world have been developing light-weight concrete incorporating mixed plastic waste, the latter comprising anywhere from 10% to 60% of the volume, particularly with the addition of high density polyethylene.

For example New Zealand company Enviroplaz can use unsorted, unwashed plastic packaging to produce Plazrok, a polymer aggregate for creating a concrete which is up to 40% lighter than standard material. In addition, the same company has an alternative to metal and fibreglass panels in the form of Plaztuff, a fully recyclable, non-corroding material which is one-seventh the weight of steel. It has even been used to build boats as well as land-based items such as skips and playground furniture.

Therefore what might appear to be an intractable problem appears to have a variety of overlapping solutions that allow sustainable development in the building and civil engineering sector. It is somewhat unfortunate then that the conservative nature of these industries has until recently stalled progress in replacing a massive pollutant with much more environmentally sound alternatives. Clearly, green architecture doesn't have to be the sole prerogative of the driftwood dreamers; young entrepreneurs around the world are seizing the opportunity to create alternatives to the destructive effects of construction.

Cow farts and climate fiddling: has agriculture prevented a new glaciation?

Call me an old grouch, but I have to say that one of my bugbears is the use of the term 'ice age' when what is usually meant is a glacial period. We currently live in an interglacial (i.e. warmer) era, the last glaciation having ended about 11,700 years ago. These periods are part of the Quaternary glaciation that has existed for almost 2.6 million years and deserving of the name 'Ice Age', with alternating but irregular cycles of warm and cold. There, that wasn't too difficult now, was it?

What is rather more interesting is that certain geology textbooks published from the 1940s to 1970s hypothesised that the Earth is overdue for the next glaciation. Since the evidence suggests the last glacial era ended in a matter of decades, the proposed future growth of the ice sheets could be equally rapid. Subsequent research has shown this notion to be flawed, with reliance on extremely limited data leading to over-confident conclusions. In fact, current estimates put interglacial periods as lasting anywhere from ten thousand to fifty thousand years, so even without human intervention in global climate, there would presumably be little to panic about just yet.

Over the past three decades or so this cooling hypothesis has given way to the opposing notion of a rapid increase in global temperatures. You only have to read such recent news items as the breakaway of a six thousand square kilometre piece of the Antarctic ice shelf to realise something is going on, regardless of whether you believe it is manmade, natural or a combination of both. But there is a minority of scientists who claim there is evidence for global warming - and an associated postponement of the next glaciation - having begun thousands of years prior to the Industrial Revolution. This then generates two key questions:

1. Has there been a genuine steady increase in global temperature or is the data flawed?
2. Assuming the increase to be accurate, is it due to natural changes (e.g. orbital variations or fluctuations in solar output) or is it anthropogenic, that is caused by human activity?

As anyone with even a vague interest in or knowledge of climate understands, the study of temperature variation over long timescales is fraught with issues, with computer modelling often seen as the only way to fill in the gaps. Therefore, like weather forecasting, it is far from being an exact science (insert as many smileys here as deemed appropriate). Although there are climate-recording techniques involving dendrochronology (tree rings) and coral growth that cover the past few thousand years, and ice cores that go back hundreds of thousands, there are still gaps and assumptions that mean the reconstructions involve variable margins of error. One cross-discipline assumption is that species found in the fossil record thrived in environments - and crucially at temperatures - similar to their descendants today. All in all this indicates that none of the numerous charts and diagrams displaying global temperatures over the past twelve thousand years are completely accurate, being more along the lines of a reconstruction via extrapolation.

Having looked at some of these charts I have to say that to my untrained eye there is extremely limited correlation for the majority of the post-glacial epoch. There have been several short-term fluctuations in both directions in the past two thousand years alone, from the so-called Mediaeval Warm Period to the Little Ice Age of the Thirteenth to Nineteenth centuries. One issue of great importance is just how wide a region did these two anomalous periods cover outside of Europe and western Asia? Assuming however that the gradual warming hypothesis is correct, what are the pertinent details?

Developed in the 1920s, the Milankovitch cycles provide a reasonable fit for the evidence of regular, long-term variations in the global climate. The theory states that changes in the Earth's orbit and axial tilt are the primary causes of these variations, although the timelines do not provide indisputable correlation. This margin of error has helped to lead other researchers towards an anthropogenic cause for a gradual increase in planet-wide warming since the last glaciation.

The first I heard of this was via Professor Iain Stewart's 2010 BBC series How Earth Made Us, in which he summarised the ideas of American palaeoclimatologist Professor William Ruddiman, author of Plows, Plagues and Petroleum: How Humans Took Control of Climate. Although many authors, Jared Diamond amongst them, have noted the effects of regional climate on local agriculture and indeed the society engaged in farming, Professor Ruddiman is a key exponent of the reverse: that pre-industrial global warming has resulted from human activities. Specifically, he argues that the development of agriculture has led to increases in atmospheric methane and carbon dioxide, creating an artificial greenhouse effect long before burning fossil fuels became ubiquitous. It is this form of climate change that has been cited as postponing the next glaciation, assuming that the current interglacial is at the shorter end of such timescales. Ruddiman's research defines two major causes for an increase in these greenhouse gases:

1. Increased carbon dioxide emissions from burning vegetation, especially trees, as a form of land clearance, i.e. slash and burn agriculture.
2. Increased methane from certain crops, especially rice, and from ruminant species, mostly cattle and sheep/goat.

There are of course issues surrounding many of the details, even down to accurately pinpointing the start dates of human agriculture around the world. The earliest evidence of farming in the Near East is usually dated to a few millennia after the end of the last glaciation, with animal husbandry preceding the cultivation of crops. One key issue concerns the lack of sophistication in estimating the area of cultivated land and ruminant population size until comparatively recent times, especially outside of Western Europe. Therefore generally unsatisfactory data concerning global climate is accompanied by even less knowledge concerning the scale of agriculture across the planet for most of its existence.

The archaeological evidence in New Zealand proves without a doubt that the ancestors of today's Maori, who probably first settled the islands in the Thirteenth Century, undertook enormous land clearance schemes. Therefore even cultures remote from the primary agricultural civilisations have used similar techniques on a wide scale. The magnitude of these works challenges the assumption that until chemical fertilisers and pesticides were developed in the Twentieth Century, the area of land required per person had altered little since the first farmers. In a 2013 report Professor Ruddiman claims that the level of agriculture practiced by New Zealand Maori is just one example of wider-scale agricultural land use in pre-industrial societies.

As for the role played by domesticated livestock, Ruddiman goes on to argue that ice core data shows an anomalous increase in atmospheric methane from circa 3000BCE onwards. He hypothesises that a rising human population led to a corresponding increase in the scale of agriculture, with rice paddies and ruminants the prime suspects. As mentioned above, the number of animals and size of cultivated areas remain largely conjectural for much of the period in question.  Estimates suggest that contemporary livestock are responsible for 37% of anthropogenic methane and 9% of anthropogenic carbon dioxide whilst cultivated rice may be generating up to 20% of anthropogenic methane. Extrapolating back in time allows the hypothesis to gain credence, despite lack of access to exact data.

In addition, researchers both in support and opposition to pre-industrial anthropogenic global warming admit that the complexity of feedback loops, particularly with respect to the role of temperature variation in the oceans, further complicates matters. Indeed, such intricacy, including the potential latency between cause and effect, means that proponents of Professor Ruddiman's ideas could be using selective data for support whilst suppressing its antithesis. Needless to say, cherry-picking results is hardly model science.

There are certainly some intriguing aspects to this idea of pre-industrial anthropogenic climate change, but personally I think the jury is still out (as I believe it is for the majority of professionals in this area).  There just isn't the level of data to guarantee its validity and what data is available doesn't provide enough correlation to rule out other causes. I still think such research is useful, since it could well prove essential in the fight to mitigate industrial-era global warming. The more we know about longer term variations in climate change, the better the chance we have of understanding the causes - and potentially the solutions - to our current predicament. And who knows, the research might even persuade a few of the naysayers to move in the right direction. That can't be bad!

Mopping up spilt milk: pollution in the New Zealand dairy sector

It's been slow to dawn on New Zealanders, but for a country that prides itself on a '100% Pure' image our environmental pollution record is fairly appalling - and shows few signs of alleviation. Politicians who point to the large percentage of the nation's electricity generation coming from renewable sources, not to mention the slow but sturdy growth in hybrid vehicles, are completely missing the point: it has been claimed that over half of New Zealand's greenhouse gas emissions emanate from agri business.

Although the quantity of sheep in the country has plummeted from a 1982 peak of around 70 million to less than 30 million last year, cattle numbers continue to rise. There are about 3.6 million livestock on beef farms and circa 6.5 million dairy cattle. The latter sector generates twenty percent of New Zealand's exports and seven percent of its GDP, so it forms a substantial component of the kiwi economy. But with plans to double the country's dairy production by 2025, the term 'sustainable development' appears to be, well, unsustainable.

Since cattle create as much waste product as fourteen humans, it's not difficult to imagine some of the more obvious forms of dairy pollutant, smell and all. As New Zealand dung beetles are primarily forest dwellers there have been trials of introduced dung beetle species to help clean up the waste, with a reduction in nitrous oxide emissions from the soil and a lowering of cattle disease as side benefits. However, pastoral poo is only one element in the catalogue of pollutants caused by dairy farming.

Last summer I was taken to an outdoor swimming hole not far from Wanganui, consisting of a rectangular concrete-lined pool situated on the edge of a forest. I was informed that children had swam there until a decade or so, but no more: several signs warned that the water is contaminated and no longer safe for humans. This story has been repeated throughout New Zealand, with agriculture being by far the most common culprit. It isn't just artificial environments that have this problem; reports suggest that within the past twenty years about two-thirds of monitored swimming areas within rivers have become too polluted. And that's just for people; there's far less concern for the effects on river fauna and flora.

Although environmentalists have been issuing warnings for years, not enough has been done to alleviate this problem. Last month approximately five thousand inhabitants of Havelock North were taken ill due to tap water contaminated by campylobacter. The source was a series of bores which the director of the Infectious Diseases Research Centre at Massey University, Professor Nigel French, put down to pollution from sheep and cattle. Sources of contamination could include carcases of dead livestock, as well as faecal matter getting into waterways that provide the source of unchlorinated - and therefore at risk - tap water.

In fact, the outbreak appears to be the tip of the iceberg. Despite some hundreds of cases of illegal effluent discharge brought against New Zealand farmers each year, many more escape prosecution. It has to be said this seems to be a regular occurrence for the Ministry for Primary Industries, judging by the recent reports of their waiving prosecutions for commercial fishing vessels caught flouting bycatch and dumping laws. Turning a blind eye seems to be the order of the day when it comes to protecting food production - or at least the food producers. This philosophy seems to be driven by those who clearly have little understanding of the complexity - and at times fragility - of food webs. Not so much short-term thinking as profound myopia!

In addition to the organic matter there are chemical pollutants that can find their way into water supplies situated close to farms. Since the 1990s, the New Zealand Ministry for the Environment has been monitoring ground water for nitrates and has found levels substantially above those recommended for drinking water. Although chemical fertiliser has been blamed in addition to livestock effluent, environmental mapping suggests the latter is the primary cause, since the polluted areas heavily coincide with the widest-scale dairy production.

As well as polluting waterways dairy farmers have also been caught stealing billions of litres of water each year from rivers and aquifers, especially in the Canterbury region. Whilst not a form of pollution per se, this is obviously somewhat lacking in the environmentally-friendly stakes. The deforestation of low-lying plains for cattle grazing is also a source of pollution, as the lack of tree roots, besides allowing greater flooding, can generate increased run-off into rivers. This polluted water can lead to algal blooms, lowering oxygen levels and so endangering freshwater fish. That might not sound of any great concern except to diehard anglers, but for any whitebait fans, four of the five Galaxiidae species whose young form this delicacy are now said to be threatened.

The systematic destruction of forests to make way for pastoral land use has been repeatedly raised as a concern not just by environmental organisations but by the New Zealand Ministry of Agriculture and Forestry (MAF) itself. Their 2006 report claimed close to half a million hectares of the nation's forests were at risk of conversion to land for cattle grazing.

In addition, overseas forests are also affected: since 2008 the amount of palm kernels imported into New Zealand as a dairy cattle feed supplement has doubled to over 2 million tons per annum. This accounts for about twenty-five percent of global production and comes at the expense of destruction of rainforests in nations including Indonesia and Malaysia. Although the state-owned farm company Landcorp Farming Ltd is in the process of moving to a different supplement over the next year or so, the dairy giant Fonterra has not announced similar intentions. What's wrong with those guys: a surfeit of Milton Friedman in their formative years?

Having covered solids and liquids, it's time to move on to gas. As I've mentioned on various occasions, methane is a primary greenhouse gas. It was therefore shocking to discover that per capita, New Zealand has the greatest annual methane emission rate worldwide, accounting for over forty percent of the country's greenhouse gas emanations. The methane emission from dairy cattle alone has continually increased over the past quarter century, although the amount reported varies from ten percent to a whopping fifty percent or so. Perhaps that's not surprising, considering cattle can each generate up to 500 litres of methane per day!

There is some recent cause for hope, with various trials under way to reduce bovine emissions. These range from vaccination to selective breeding to diets bases on forage rape, with the latter showing that the change in feed affects fermentation - and therefore reduces methane production - in sheep. However, it wouldn't hurt to see the Government funding more research in this matter: one widely-reported paper last year was Massey University's The New Zealand Dairy Farming: Milking Our Environment for All its Worth, which received much criticism from the dairy sector when it was revealed to consist primarily of a student thesis.

It's very easy to become depressed with such deleterious effects coming from just one sector. Of course no nation can afford to rest on its laurels: we cannot turn the clock back. The halcyon image of bucolic ruralism is a myth perpetrated by those who have never worked on the land and farmers deserve the benefits of modern technology in their work as much as anyone. The development of sophisticated tools and software can aid the dairy sector in preserving the environment. as long as there is enough public money to support this eco-friendly research. But Government funding for this type of sustainable development appears to be sadly lacking. Doesn't it make sense that those who run God's Own Country should try a little harder to prove that the 100% Pure tagline isn't just marketing spin?

How green is my alley? Reduce, reuse & recycle

British artist Richard Hamilton's 1957 definition of pop art included the terms 'transient', 'expendable', 'mass-produced', and 'Big Business'. We've come a long way since similar contemporary cultural attitudes led to throwaway clothing and disposable furniture, but there's still plenty that needs to be done before we achieve anything approaching sustainable development. The recent news articles showing that like the Pacific, the North Atlantic Ocean has its own enormous patch of floating plastic waste, clearly define a multinational problem: but what can the average Briton do to help the environment?

The three green 'R's of reduce, reuse and recycle involve a lot of statistics published by a variety of concerns, ranging from manufacturers to environmental groups. Going with the old saying that there are lies, damn lies and you-know-what, how can the public find a way through the minefield? As an example, estimates for the UK's annual waste total vary from 100 million to 400 million tonnes - although even the lower figure is more than enough! In recent years there have been several scandals involving potentially dangerous waste collected by local councils for recycling, only to be sent to developing countries where it is picked over by scavengers. Clearly, in some cases, out of sight is also out of mind.

Perhaps this shouldn't be too surprising considering how quickly we've had to adopt ecologically-motivated measures, but another concern is the enormous regional variation in recycling collection, waste processing and recovery. Lack of processing plants and a deficiency of recycling knowledge within councils supply yet another example of the postcode lottery. In response to this some local communities are taking matters into their own hands, such as the Somerset village of Chew Magna, where the inhabitants are attempting to gain zero waste status.

In addition to the lack of processing facilities another issue is sorting, although the use of high-tech approaches such as x-ray fluorescence and infra-red spectroscopy may increase efficiency, especially of plastics where recycling can create enormous savings in everything from oil to water. It isn't just the percentage that is recycled that counts, but how effective the processing and recovery methods are and whether as a nation we can reduce the amount of waste in the first place. Britain is an intensely consumerist nation and as if we need further proof, our household waste continues to grow by about 3% each year.

One of the most astonishing statistics (you see, they keep on cropping up), is the estimated 17.5 billion plastic bags given away in British shops every year. This amounts to over 130,000 tonnes of plastic, very few of which are composed of biodegradable material. An example of how quickly habits could change is shown by Ireland's introduction of a tax on plastic bags in 2002, which lead to an almost immediate reduction of over 90%. What's the difference to the UK? As far as I can tell, it boils down to the simple fact that unlike in Ireland, we have companies who make plastic bags: far be it from the Government to inhibit sales within our increasingly pitiful manufacturing base.

Despite the popularity of city allotments we are so divorced from food sources as to blindly follow use-by dates without actually checking the food itself. Recent evidence, including personal experiments by yours truly, show that in many cases the dates are wildly pessimistic (fingers crossed, I haven't been poisoned yet.) Again the figures vary widely, but estimates for food wastage in Britain range from 2.5 million to 8 million tonnes per year, which even for the lower figure equates to 18 million tonnes of carbon dioxide. Food safety scares have a lot to answer for, but surely effective food science education of adults as well as children is the obvious solution? After all, it would save us at least £10 billion per year on our shopping bills.

Of course it isn't just the consumer who is at fault: British industry must bear much of the blame. Every year we each spend up to one-sixth of our food budget on packaging, much of which uses standard sizes to cut manufacturing costs at the expense of material wastage. We could do worse than look at South Korea, where over the past decade legislation has reduced both the size and materials that can be used for packaging processed foods.

Another issue is planned obsolescence. Both the Trading Standards Institute and the Office of Fair Trading investigate consumer claims of items ceasing to work shortly after the initial warranty expires, but there are plenty of less obvious instances of products deliberately built to limits short of their potential working life, such as printer cartridges and rechargeable batteries. More insidious still is the use of advertising and clever marketing, combined with long-term release cycles, to promote a more rapid replacement of items than is really necessary. This 'obsolescence of desirability' is particularly obvious with mobile phones, which rapidly outstripped manufacturer's sales estimates in the early 1990s and are now updated on the basis of a fashionable new function or user interface rather than improvements to their core purpose. There can be no better illustration of the needlessly short life span of electronic goods than the seven metre tall WEEE Man sculpture at the Eden Project in Cornwall, which is composed of the consumer goods the average British citizen gets through in a lifetime - including no less than 35 mobile phones!

One irony is that the rapid development of storage formats over the past few decades has created a cycle of obsolescence from floppy disks to laser discs at a time we most need to counter expendability. Perhaps the current generation of 'virtual' devices such as Ipods and Ipads will help offset this, as long as their material and energy costs don't outweigh the savings in paper and packaging.

We cannot be in any doubt that things are changing for the better, but the big question is whether it is fast enough. The world's third largest retailer, Tesco, plans to be carbon neutral…in about forty years time. Many office buildings are already zero carbon and the Government plans for all new homes to be built to this standard from 2016. Meanwhile the Welsh firm Affresol has developed TPR, a wholly-recyclable substance stronger than concrete yet made mostly of waste and intended to provide load-bearing walls for buildings; fingers crossed for their pilot project!

Obviously just cutting back on domestic waste and power consumption will not do as much as reducing fossil fuel usage, but every little bit helps. A final shocking statistic: every Christmas this nation uses 8,000 tonnes of wrapping paper. Do we really need that amount? And as for carbon-trading - that's a whole other issue...