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Essay: Cement and concrete

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  • Subject area(s): Engineering essays
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  • Published: 22 September 2015*
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  • Words: 1,530 (approx)
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Water, unsurprisingly, is the number one most consumed substance in the world. Concrete, surprisingly, is the second most consumed substance in the world. Concrete is created by mixing cement, water and aggregate. Cement is the vital binding component in the concrete production process. This combination is the most abundantly manufactured material in the world and is one the most universally used construction materials. The ancient Babylonians and Egyptians (enviroliteracy, 2013) were the first to discover and incorporate the use of cement. Cement and concrete can be found is almost every, past and present, structure currently known to man. So much so that the demand for concrete is expected to double in the next 30 years. All these points highlight the past, present and future popularity and demand for cement. However, the environmental impacts imposed by both the production and use of cement are catastrophic. Cement is produced by combining limestone or chalk with clay in a kiln and then heating this mixture up to approximately 1450??. This produces nodules of clinker which are then ground up in a ball mill (concrete.org, 2013). This entire production process is highly energy intensive and emits copious amounts of carbon dioxide. These are but a few of the catastrophic environmental impacts that will be discussed in this paper. Manners in which to reduce these impacts will also be addressed.
CO_2 Emissions and Global Warming
The Oxford Dictionary defines ‘Global Warming’ as the incremental rise in the temperature of the earth’s atmosphere which can be attributed to the greenhouse effect caused by the excess levels of carbon dioxide (CO_2), CFC’s and other pollutants (oxforddictionaries, 2013). The cement industry is responsible for approximately 7-8% of all CO_2 emissions produced by man (unep, 2013). This is due to the fact that the process of creating cement utilises numerous natural resources such as limestone and sand, large amounts of fuel oil and exuberant amounts of electricity. Per tonne of cement produced, 60-130kg of fuel and 110KWh are required (unep, 2013). This whole process will emit approximately one tonne of CO_2 into the atmosphere, per tonne of cement produced. It is fairly obvious that the current production process is careless in terms of the amount of CO_2 produced, the amount of electricity it requires and the exuberant level of resource consumption needed. In terms of global warming, cement production is definitely a major contributor. Global warming is a global ravaging epidemic that must be controlled. An important step in controlling global warming would be to evaluate the current cement production process and improve upon it. Processes are been investigated in which there is potential for reducing the amount of greenhouse emissions from the cement industry. In the past few years there has been much research done in this field and there are positive and potential solutions to the CO_2 emissions problem. The most attractive and economical solution to the environmental impact caused by the production of cement would be, simply, to reduce the amount of cement produced. If there is less cement produced then there will be less of an environmental impact. This can be achieved by utilising alternative materials to cement. Common alternatives are waste products from industrial processes that include fly-ash, granulated blast-furnace slag and silica fume (unep, 2013). All of which, are suitable alternatives and when blended in the appropriate ratios and activated correctly, allows for the entire cement production process to become more considerate, efficient and effective. The use of alternative materials will reduce the amount of CO_2 emissions, curb the excessive energy usage and reduce the resource consumptions.
The cement industry is largely considered as one of the global leaders of pollution. The manner in which the natural resources required to make cement are obtained to the actual production process of cement are all horribly guilty of polluting the environment. The key culprits that significantly contribute to the imbalances of the environment are nitrogen oxide (NO_x), sulphur dioxide (SO_2), carbon monoxide (CO) and grey dust (Air Pollution Control, 2012). Alarmingly, the cement production process is also responsible for mercury emissions. Mercury is classified as a persistent, bio-accumulative toxic (PBT) (Jane Harley, 2007). All these pollutants actively degraded both the air and water quality. Many other foreign chemicals emitted are classified as Volatile Organic Carbon compounds (VOCs) (Air Pollution Control, 2012). These ‘Volatile Compounds’ are solely responsible for toxicity and the photochemical reaction that produces smog. Additionally, all these fugitive pollutants, when exposed to the general public can cause an array of medical conditions. They are responsible for causing lung damage, aggravate existing cardiovascular conditions and can even reduce the amount of oxygen delivered to the body. Mercury, when exposed to children can cause neurological problems and hinder the ability of development. The compound know as ‘grey dust’ has also been heavily linked as been a primary cause of Tuberculoses. The cement industry has a legislative and moral right to try and minimise the amount of pollutants entering the atmosphere. Their priority concern should be in ways in which they can reduce the pollution caused by the cement production process. There have been many technological advancements in recent years which provide the cement industry with many opportunities in which they can reduce the amount of pollutants entering the atmosphere. The amount of nitrogen oxide emissions can be reduced by implementing efficient and effective kiln designs. Technology and specific engineering software allows for a better understanding of the cement production process and allows for better, more environmentally friendly kilns to be designed. The amount of sulphur dioxide emissions can be heavily reduced by opting for the use of low-sulphur fuels. The use of low-sulphur fuels has no adverse affect on the quality of the final product. The use of such fuels should be implemented as a compulsory measure. The art of air pollution control has made many technological breakthroughs in recent years with methods that control dust, such as the Flexible Pulse Jet Filters, Electrostatic Precipitators and Wet Scrubbers. However, in terms of effectiveness and flexibility the Ordinary Bag House method is the most proficient. This filtration device filters the air through special fabric bags which capture the fugitive particles. This whole process is extremely efficient in controlling emissions and reducing the extent to which the cement industry pollutes the environment. Unfortunately there are no technological advancements that have been developed to reduce the amount of mercury emissions. The conditions and environment in which mercury emissions are produced is extremely harsh and all methods implemented have been ineffective. However, the other precautions and steps have proven successful and not only will these steps reduce negative emissions but they will also protect the general public.
The combination of cement, water and aggregate to form concrete is a very important partnership. Concrete as a building material is extremely popular due to the fact that it is very reliable, durable and cheap when compared to alternatives. Concrete is used in almost every structure and plays a pivotal role in providing the structural rigidity of these structures. The fact of the matter is that we depend on cement and concrete. But that does not justify the blatant environmental impacts imposed by the production process. Many argue that the cement industry has been blatant for far too long and that steps need to be implemented in which these impacts can be reduced. The production process can be broken up into steps: obtaining raw materials, combining these raw materials and refining the product. Each and every step is extremely intensive in terms of the amount of resources it uses. The oil fuel consumption during this process is exuberant and the electrical power usage is appalling. All these facts are incomparable to the disastrous CO_2 emissions. These CO_2 are heavily contributing to Global Warming and must be controlled. The cement industry is also horribly guilty of polluting the natural environment. The chemicals and particles released during the production process has a horrible adverse effect on both the natural environment and the general population. Many serious medical conditions have been attributed to the emissions caused by the cement production process. Some might argue that all these disadvantages caused by cement production, heavily outweigh its advantages. The cement industry should concern themselves with ways in which they can reduce or eliminate these serious disadvantages. This can be achieved by opting for alternate materials to cement. There has been much success in using alternative materials. No major adverse affects have been recorded when using these alternative materials, which is its highlighting fact. The use of these alternative materials will reduce the amount of resources consumed in the production process and most importantly reduce the amount of CO_2 emissions. Also, the amount pollutants emitted into the environment can be drastically reduced by considering alternate kiln designs, opting for more efficient safety measures and better suited filtration methods. The cement industry should look at all of this as an advantage. They now have an opportunity to achieve a competitive edge in a cut-throat market. A production plant which has taken these environmental aspects into consideration during the cement production process will most likely experience better business. It also provides the cement industry a chance to clear its moral conscious and become ‘greener’.

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