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The Story of Concrete and The Threat it Poses to The Natural World
Development, in the context of nation building, usually refers to infrastructural development. The word ‘infrastructure’ which means the basic systems and services that are necessary for a country or an organization to run smoothly, for example buildings, transport and water and power supplies, originated in the early 20th century somewhere in the European continent. In just a century it has made its impact felt in every nook and corner of our planet even the Arctic and Antarctic Circles.
Whether it is a residential building, a rigid pavement, a bridge, a dam in a hydro-electric project, the only construction material that comes to our mind in today’s world isconcrete. It is perceived that this material of immense durability has made our life easier and yes, it is true to a considerable extent. Without concrete we cannot think of multi-storied buildings providing shelter to a huge number of families in a small plot of land in a country with a rapidly increasing population, modern health infrastructure and durable highways. However with the ever- evolving definitionof needs and necessities, the demand for infrastructure and its development has exponentially increased in the recent times and consequently more concretehas found its way onto the Earth’s surface.
When we had asphalt roads, concrete highways became our need for a better future. When we have four lane highways, we are craving for evenwider expressways. Similarly, we have started stuffing our homes and our lives alike with electronic gadgets, now these have become our necessities. Consequently, the need for more and more energy to keep them running has emerged. In the quest for more electricity generation we started building concrete dams on our rivers without bothering to submerge thousands of hectares of green forests, villages. Small dams, big dams and then mega dams and millions of tonnes of concrete kept on flowing and accumulating on the Earth’s surface. These structures have their own numerous environmental impacts which shall have to be addressed separately. In this article the impacts of Concrete and its constituents shall be discussed with an objective to figure out the magnitude of the threat it poses on the natural world if we continue on this path in the same pace.
The three main constituents of concrete are cement, sand and aggregates (gravel).Cement production is one of the leading contributors of CO2 emissions, it causes around 2 - 3% of the worldwide total of CO2 emissions. According to a report on India cement industry published by India Brand Equity Foundation (IBEF), our country produces more than 300 million metric tonnes of cement in a year and is the second biggest producer of cement after China. Apart from CO2 emissions Cement production adversely affects the natural environment in a number of ways. Lime stone being the major ingredient in Cement clinkers; rampant limestone mining in biodiversity rich areas has led to loss of habitat especially of the endemic flora and fauna which are of immense ecological importance. Moreover, open cast limestone mining alters the geomorphology of the area triggering landslides, rock falls etc. Alkaline discharge from limestone mines pollutes the receiving waterbodies affecting the aquatic life forms all well as contaminates the prime sources of drinking water. Similarly other minerals such as gypsum have to be mined from within the earth crust for production of cement. With each tonne of cement produced we are adding more than 0.9tonnes of carbon dioxide into the atmosphere, more than 1.65 tonnes of limestone has to be quarried from the nature’s reserves and around 0.4 tonnes of clay has to be extracted from the earth crust.
After cement, sand and gravel are the major constituents of concrete. For each tonne of cement, the construction industry requires about six to seven tonnes of sand and gravel. In today’s world billions of tonnes of aggregates (sand and gravel) is used every year for production of concrete; if this entire quantity is piled up at one place, it would resemble a huge mountain. And each year we are ripping off mountains of sand and gravel from the body of our planet Earth. The sand and gravel at the riverbed acts as the river’s skeletal structure which helps the river to maintain its course. River sand also acts as a medium for natural water purification as well as ground water recharge. Further it is a part of the natural habitat for several aquatic life forms and also nesting and breeding grounds for several rare amphibian and reptile species. Extraction of sand destroys the natural habitat of these species thereby disrupting with the entire ecosystem. Excessive sand mining from the river bed also has enormous hydrological impacts too. Extraction of sand and gravel from the river bed reduces its erosion resistance, thus accelerates scouring of the streambed leading to geomorphic changes, which affects the course of the river, eroding banks and finally causing floods. Apart from rivers, aggregates are quarried from hills and mountains. Stone quarries leave scars on our natural landscapes which is difficult to heal. Quarrying affects the entire ecosystem. Apart from loss of vegetation and habitat it affects the natural drainage system, augments erosion and triggers siltation of nearby water bodies. This whole phenomenon gives rise to a vicious circle of development and destruction. Cement, sand and aggregates in prescribed proportion and after addition of water to this mix, the most durable building material on earth is ready to build a whole new grey concrete world. Bridges, skyscrapers, expressways, dams, retaining walls and the list goes on. And on the other side with ever increasing concrete structures our cities are being converted into heat islands. Concrete surfaces absorb the heat from the sunrays and add to the urban heat island (UHI) effect. Moreover, water usage in concrete amounts to almost one tenth of world’s Industrial water use adding to the woes in the water stressed cities and towns. Further, concrete production is one of the biggest sources of particulates emission causing respiratory diseases to worsen. Most part of the earth’s surface is being covered with an impermeable concrete layer especially in our cities. This impermeable layer of concrete does not allow rain water to percolate obstructing the natural process of ground water recharge. Ground water depletion has triggered water scarcity in most of our cities which does not have any accessible surface water source. In recent times urban flooding has become a frequent occurrence. Concrete is to be blamed for this as well. Reduction in infiltration of rain water into the soil and increase of runoff from concrete surfaces is the leading cause for flash floods in the modern and developed cities.
We cannot deny the fact that despite of its durability and wide range of utility, concrete has a profound ecological footprint. Concrete and the process of its production have adversely affected and continuing to affect the entire ecosystem, it has adversely affected river systems, it has been degrading the air quality, augmenting green house effect, heating up the atmosphere, triggering loss of natural habitat, accelerating occurrence of flash floods; in a nutshell it has become a material of destruction rather than development. It is the prime need of the hour to evaluate the necessity of each and every concrete structure which is being proposed to be built in our near future. For example, to reduce traffic congestion the most acceptable solution might be a flyover made up of thousands of tonnes of concrete in order to make way for the ever increasing number of vehicles that run on fossil fuel emitting harmful gases in to our atmosphere. May be, we can search for some sustainable alternatives in the form of better public transportation, may be more of us can choose greener modes of transportation like bicycles and e-bikes which requires less space and less fuel. Moreover, there is an enormous scope of Research and Development to reduce the footprint of concrete. Development of smart materials as alternatives for sand and aggregate, recycled concrete and similar innovations in the field of sustainable building materials have to be encouraged. It might not be an easy task to find greener alternatives all of a sudden but gradually and collectively we can. With time we will have to explore, innovate and switch to sustainable alternatives as these are evolving as the only tools left for us to sustain our life on this planet. And the Earth continues to provide enough to satisfy every man's needs.
