Puneet Arora explains that construction and construction material are major areas where man has been dependent on natural resources – but there is a clear need to be more efficient in using our natural resources.
For an engineer, the best, most efficient and cost effective solutions come from nature. Since ages, traditional Indian construction has been using natural products in abundance. However, with increasing population and resulting demand in recent times, there has been a huge increase in extraction and use of available resources. Over dependence on limited resources is taking its toll. Unplanned urbanisation, industrialisation and over population also create imbalance in the eco-system by infringing upon the natural habitat of the flora and fauna of the area. This is visible not just in terms of resource shortages, heavy deforestation and depleting wildlife but also in the form of extreme climate, droughts, floods, environment pollution and ecological imbalances threatening human existence itself. Nature has been warning us in its many manifestations to mend our ways and respect the delicate balance.
Construction and construction material are major areas where man has been dependent on natural resources. Recent awareness and focus on afforestation, control on mining of metal ores, stones, minerals, aggregates and sand has come after visible effects of environmental damage. There is a clear need to be more efficient in using our natural resources.
The construction sector at large and cement sector specifically has also done its bit to adopt greener technology to reduce and mitigate some of the damaging effects. Some simple and basic steps can have a dominant impact towards environment friendly construction and development.
Local is GREEN: In search of green construction material, there is an increasing trend to adopt modern material. An important aspect for engineers and architects is to maximise the use of locally available construction material to the extent permitted by aesthetic and utility needs. We may be burning much more carbon in transporting “an eco-friendly” product from thousands of kilometres for avoiding use of locally available material which may be even bamboo, jute or mined stone. Use of local material will generally have lesser environment impact. Lower cost is definitely an added advantage.
Use of light-weight construction material: Structural safety against imposed load and natural events like wind and earthquake is an important aspect of building design and construction. With right selection of material which is light weight yet strong, the dead load imposed of the superstructure can be considerably reduced. With use of advanced composites and efficient technology, even equipment load is being reduced. Such developments go a long way in reducing requirements of cement, sand, stone and steel through optimum structural design.
Slag and Pozzolana cement: Manufacture and use of Pozzolana Portland Cement (PPC) and Ground Granulated Blast-furnace Slag (GGBS) Cement or Portland Slag Cement (PSC) is now a norm. By blending fly ash and blast furnace slag which were considered disposable waste by power plants and steel manufacturing units, the consumption of limestone is reduced by 25 to 50%. The effective savings are enormous especially when savings in electrical and thermal energy consumption in all processes are taken into account. The use obviously has much desired positive environmental benefits by conserving use of minerals as well as minimising waste disposal issues. For end users, the product available has been made superior by technology in terms of strength, durability and corrosion resistance properties.
High tensile ductile reinforcement: A praise worthy product of technology is high tensile reinforcement used in Reinforced Cement Concrete (RCC) construction. Now high yield strength (Fe500) steel rebars are being predominantly used in place of traditional mild steel (Fe240) considerably reducing the weight of steel required in RCC. Weldability of these high strength rebars offers scope of additional 2 to 5% reduction in quantity by welding in place of overlap. Thus, the total demand in terms of steel requirement can be substantially reduced with use of new technology increasing sustainability of our iron ore resources.
Precast pre-stressed construction: Present day mega infrastructure projects including metro railway, highway bridges, large construction projects and railways have adopted precast and pre-stressed RCC construction techniques. These technologies offer benefits of best utilisation of material properties resulting in reduced need of cement and steel. The construction time and material wastage is also considerably reduced by means of centralized and controlled manufacture of precast components. No doubt, the quality and aesthetics of RCC precast components is vastly superior to in-situ casting. Reduction in weight offers additional savings.
Efficient energy utilisation: The rising fuel & electricity costs have driven us to development and adoption of energy efficient technologies. Our traditional Vaastu concepts have an underlying theme of maximising use of natural light and ventilation. The new-age green technologies are re-emphasising these concepts. Hollow block masonry for construction of exterior walls is being re-invented to reduce the impact of extreme weather on building interiors. With better architecture and daylight simulation models, the need for artificial lights and ventilation can be minimised resulting in huge reduction in electricity demand.New age technologies such as LED lighting, building and plant energy management systems help in the reduction of our energy footprint further. Modern industrial establishments are also adopting heat conservation and regeneration techniques for increasing energy efficiencies. Use of bio-wastes as alternative fuels, use of solar, wind and tidal energy etc. provide avenues for conserving our scarce resources.
Use of eco sensitive and recyclable materials: Increasing use of fibre composites, glass, aluminium, ash bricks etc.in construction have significantly reduced the carbon imprint as well as demand pressure on our natural resources. Some new age construction material is also being designed to be recyclable while simultaneously saving construction time, water and energy needs. Redevelopment of infrastructure has also provided for avenues to recycle scrap and debris generated from demolished infrastructure for new construction. Recycling of metal and glass is commonplace. Use of crushed, demolished concrete as aggregate is slowly catching up.
Water and air conservation: Another great feature of green construction is decrease in water requirement. Responsible industry is targeting zero discharge as well as zero pollution by innovation and technology. Today,the increased universal awareness for sustainability is driving innovation for eco-friendly solutions. Use of additives for concrete that reduce water requirement is finding good use. Use of curing compounds further helps reduce water required for curing of concrete.
Very rightly said – Environment is not what we have inherited from our ancestors but what we owe to the future generations. With ever increasing demand of natural resources, there is a greater need to save our planet from environment deterioration. Conserving our ecosystem is the only way to sustain human life and our only protection against natural disasters!
(The author is Executive Director, Projects, Dalmia Bharat Group.)