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Concrete is very versatile, but!
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Q. What is the most eco Concrete/cement. How environmentally friendly is cement and where do most supplies come from? Also is there a practical limit to the raw materials.


A.
much of our cement supplies probably come from quarries in Lincolnshire and Derbyshire but Increasingly, cement is imported from countries such as Indonesia and the Philippines where labour and raw materials are cheap and environmental laws are less well enforced.

Cement is of course an important material in construction and infrastructure, but sadly there is a ‘high price to pay’ for such a cheap and readily available material. Problems range from land degradation through quarrying, to air pollution caused by the enormous amounts of dust generated and the noxious chemicals emitted from cement kilns. The very high temperatures achieved in the kilns, mean a high fuel input and subsequent output of greenhouse gases. Another important issue is one of land rights, where lack of legal ownership means that governments can easily sell off or lease land to large multinationals, which often results in displacement of local and indigenous peoples.

Cement production, in countries such as the Philippines can be highly detrimental to the health of people who work the kilns and to the surrounding communities. Sulphides and sulphates from cheap fuel are oxidised to sulphur dioxide in combustion and along with the large quantities of dust released from quarrying create air pollution on a par with nineteenth century industrial England. Pneumoconiosis, silicosis and cancer are not uncommon amongst workers. Known by campaigners as the ‘holocaust’ of the construction industry, cement production has unquestionably shortened the lives of thousands of people.

The Philippines are a group of highly populated, mountainous islands. Coastal land is valuable and there is competition for agricultural land. Cement plants, naturally, are mostly coastal to allow for easy import of fuel and export of product. However, a growing international market and increasing ownership by mining giants such as HANSON (one of world’s most aggressive acquirers of quarry and construction materials) has meant increased acquisition of ‘locally owned’ land and a vast increase in mining activity. This understandably, is not in the interest of local people.
Undoubtedly local air pollution escalates in such situations unless best possible standards are met and there is little inclination when national legislation is so lax. Not only are food growing areas also reduced, but crop productivity is affected as surrounding vegetation becomes smothered with dust from quarrying activities. River systems become polluted too and choked with run off and fall out from quarries leading to a reduction in water quality, not least because rivers experience a drastic increase in alkalinity.

The conditions surrounding cement production in Britain are not quite the same as in the overexploited developing world, but the problems exist. Pollution is more invisible, with chronic rather than acute effects, less obvious at first but more sinister. The burning of hazardous materials in cement kilns as a fuel, which at the same time disposes of industry’s waste chemicals is the main concern. According to the National Alliance of Cleaner Kilns (NACK), Castle Cement in Clitheroe make £200 K profit a month from burning this toxic waste, known to the industry as substitute liquid fuel (SLF). The Environment Agency issues permits to operators of cement kilns to burn SLF, which might make up to 40% of the fuel intake of some kilns. Some of this hazardous, toxic waste is even imported.
The burning of waste along with conventional fuels is known as ‘coincineration’. The idea was cooked up as a way of keeping down the cost of cement - and the waste bills of the chemical and pharmaceutical industries. Much of the controversy surrounding cement kilns has centred around the burning of solvents and waste oils from these industries which has given cause for concern about health.

People living in the areas around cement kilns do not like the smell of the burning waste. Neither do they like what they read in the paper about birth defects and the rise in respiratory problems amongst their children. The resulting public pressure has generated two enquiries by the House of Commons Environment Select Committees in successive governments, with both committees producing highly critical reports about the handling of such hazardous waste. It has twice been recommended that thorough surveys be carried out on human and animal health in the vicinity of the kilns but both governments have refused. Presumably there is anxiety about what a survey might find, with the added problem of what then to do with the hazardous waste.

Meanwhile the EU Scientific Committees on Food continue to sound alarms over exposure to dioxins through our diets. The main source of dioxins is incinerators where these chlorinated hydrocarbons are generated during combustion. Airborne, they are dispersed and subsequently alight on vegetation and water bodies where they enter the food chain. Wild and farmed fish have the highest levels, with eggs next, then milk and then meat. Animal products are often high in dioxins because a significant amount of feed contains fishmeal.
Dioxins do not degrade in the digestive process and so are stored in bodyfat. First born, breast fed babies take in 27 to 144 times the WHO recommended limit of dioxins in their first two months. Evidence shows that such babies, and young children, perform less well on certain cognitive tasks and may go on to have learning difficulties. A considerable proportion of the UK population are in fact exposed to higher than the recommended levels of dioxins. The Inuit have the highest dietary intake of dioxins in the world and through no fault of their own. They happen to be at the end of a very long food chain which starts with nasty industrial processes in the ‘west’.

Municipal incinerators operate under much more stringent conditions than in the past, but not so cement kilns. As ‘coincinerators’ they are not covered by the same EU Waste Incineration Standards; abatement equipment exists usually only to trap dust and spot checks for pollutants like dioxins are only carried out twice a year! The US EPA states that cement kilns burning chemical waste are the highest emitters of dioxins and kilns burning non-hazardous waste the second highest.

Offering the chemical industries free or minimal cost waste disposal in no way encourages the genuine recycling of waste or the development of new, more efficient technologies. Toxic, non-biodegradable chemicals like dioxins lurk in every ocean and continent of this earth, threatening the lives and health all of its inhabitants. The producers of waste are acting dangerously and irresponsibly and must be forced to use less hazardous materials.

It is not necessary to have vast increases in the mining of limestone and processing of cement. It has been proven that we don’t want or even need those huge dams. In the construction of offices and houses it is too easy to use large amounts of cheap cement wastefully. The building industry should be made more accountable for its excesses and whilst reducing its use of cement should look to alternatives like limecrete. A wider use of limemortar would also make possible the recycling of bricks and blocks. Unwanted demolition material should then (always) be processed on site and used for infill and hard-core, so avoiding the unnecessary use of environmentally damaging and non-renewable resources.

Fiona Gomersall

A special thanks to ‘Partizans’ for their help with research on cement quarrying in Asia.






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