Global warming from green-house-gas (GHG) effects consisting of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) has emerged as the most serious sustainability issue confronting the human civilization in recent times. In a series of reports, the United Nation’s Intergovernmental Panel on Climate Change (IPCC) has been pin-pointing the serious threat posed by global warming. IPCC’s Fifth Assessment Report1 highlighted that the GHG emissions have dramatically increased since the pre-industrial era to alarming levels. The CO2 emission level has increased sharply from 280 ppm in 1850 to around 403.3 ppm in 2016 – the highest level in 800,000 years! While this has resulted in the unprecedented increase in ocean levels and their acidification, there has been a drastic increase in extreme events – heat waves, tornados, floods, drought, etc.
IPCC’s latest special report2 on the impacts of “Global Warming of 1.50C” underlines the danger that the global warming is likely to reach 1.50C between 2030 and 2052, if it continues to increase at the current rate (Fig 1). The report draws on research conducted since nations unveiled the 2015 Paris Climate agreement, which seeks to curb GHG emissions and limit global temperature rise between 1.5 and 2°C. There is an urgent need to curb carbon emissions by at least 49% of 2017 levels by 2030 and then achieve carbon neutrality by 2050. The report also points out that limiting global warming to 1.5°C above pre-industrial levels would be a Herculean task, requiring rapid corrective actions jointly by governments, industries and societies.
India’s Vulnerability to Climate Change
India happens to be third largest CO2 emitting country in the world. However, in per capita terms, India’s contribution of GHG is not alarming. It is estimated that India’s per capita GHG emission in 2030-31 will vary from 2.77 tonnes to 5 tonnes of CO2e, which will be closer or less than the world average per capita CHG value of 4.22 tonnes CO2e.
However, there is no room for complacency. According to the latest report by HSBC3, India with its large population of 1.3 billion, is one of the most vulnerable countries to climate change, followed by Pakistan, the Philippines and Bangladesh. The bank assessed 67 developed, emerging and frontier markets on vulnerability to the physical impacts of climate change, sensitivity to extreme weather events, exposure to energy transition risks and ability to respond to climate change.
In this context, it is noteworthy that the Indian government has voluntarily pledged to abide by the following key decisions:
- To cut GHG emissions intensity by 33 to 35 percent, relative to 2005 levels, by 2030
- To achieve about 40% cumulative electric power installed capacity from non-fossil-fuel energy resources by 2030
- Set Clean Energy Targets of 100 GW Solar Power by 2022 and 60 GW Wind Power
To create an additional carbon sink of 2.5 to 3 billion tonnes of CO2 through forest and tree cover by 2030.
As far as the construction sector is concerned, construction and the built environment are the main consumers of resources ? energy, materials, water and land. Hence, both construction and built environment need to play a crucial role in achieving sustainable development. One should, therefore, appreciate that “sustainable construction” must be one of the main agendas of construction industries in all countries including India. Since concrete is the foremost material of construction, it will be highly essential to ensure the sustainability of concrete construction.
Amongst different materials of constructions such as steel, aluminium, glass, wood, etc., concrete happens to be comparatively sustainable. This is because of a variety of factors-it is made up of ingredients that are locally available, it does not produce any harmful by-product during production, it has a capacity to absorb a large proportion of agro-industrial waste, it does not corrode, it is fire-resistant and it can be recycled. Yet, it contains ordinary Portland cement, the production of which releases around 0.8 tonne of CO2 for every tonne of ordinary Portland cement produced.
Global Concrete Industry and Sustainability
Mehta provides the historic and projected annual cement and concrete consumption rates for the 75-year period from 1975 to 2050 (see Fig 2)4. He argues that if the current rate of cement and concrete consumption is not reduced in the near future, it will augment the global warming problem. Achieving major cuts in cement consumption and, at the same time, meeting the future concrete requirements of the world, is indeed a formidable task. Mehta advocates three sustainability tools, namely, (i) consume less concrete through innovative architecture and structural design (ii) use the 56- or 90-day compressive strengths criteria whenever possible to minimize the amount of cement in concrete, and (iii) consume less clinker in cement (see Fig 3).
Concrete Construction Scenario in India
Concrete construction scenario in India has witnessed significant changes during the last two decades. While a substantial volume of concrete produced in the country is still based on the old site-mixed and volume-batched practices, in recent years, the demand for higher speed of construction and improved quality necessitated adoption of mechanized and semi-mechanized techniques of construction in urban areas of India. This was conducive for the development of ready-mixed concrete (RMC).
The growth of RMC which started with metropolitan cities from the mid-1990s onwards, has spread to other major cities, and has now trickled down to tier II and III cities. No authentic data is available on the RMC industry in India; however, it is unofficially reported that there are more than 100 cities having at least one or more commercial RMC plants. Further, there seems to be a general agreement amongst industry experts that nearly 10-15 % of the cement produced in the country goes through the batch-plant concrete route. Thus, assuming an average cement content of 300 kg/m3 for the concrete produced from batch plants, it can be estimated on a rough basis that a total of around 90-120 million m3 of concrete is currently being produced by the organized concrete sector using modern batch-plant concrete in India.
Ingredients of Concrete: Does India possess Sufficient Resources?
Sustainability demands optimal utilization of non-renewable natural resources. In this context, it may be worthwhile to look into the availability of basic raw materials used in the production of concrete.
India has the distinction of being the second largest cement producer in the world, next to China. Based on the latest data from the Survey of Cement Industry, the Indian Cement Industry comprises of around 225 plants belonging to 84 companies, with an aggregate capacity of 444 million tonnes in 20145. More recent estimate6 indicates that the production level of cement would reach 340 million tonnes in 2020. Considering the huge expenditure being made on the development of physical infrastructure in the country – highways, expressways, airports, metro rails, ports, etc on the one hand and affordable housing on the others, the requirements for cement is bound to grow further beyond 2020.
Limestone is the basic raw material required in the production of cement. Although India can boast of having one of the largest reserves of limestone in the world, the total cement grade limestone reserves as classified based on United Nations Framework Classification (UNFC) system of classification, are just 8,949 million tonnes, while the reserves under the “remaining resource” category are 115,591 million tonnes7. The remaining reserves are those which have not been found economically viable due to techno-economical, environmental, social and legal aspects. Further, limestone deposits located near human settlement are not available for mining. Considering these constraints, the report of the Working Group on Cement Industry7 states … “based on the expected growth and consumption pattern, the current reserves are expected to last only for another 35-41 years”. From sustainability considerations, it is therefore prudent to use the limestone reserves sparingly, thus limiting the use of ordinary Portland cement.
Supplementary Cementious Materials (SCMs)
The limited future availability of limestone has already attracted attention towards alternative resources. These resources include a variety of supplementary cementitious materials (SCMs) such as fly ash, ground-granulated blast-furnace slag GGBS), condensed silica fume, high reactive metakaolin, rice husk ash, etc. Amongst the various SCMs, fly ash and GGBS are available in large quantities for use in cement and concrete. For example, according to the Central Electricity Authority (CEA), thermal power plants generated a total of 169.25 million tonnes of fly ash in 2016-17. Out of this, only 63% of fly ash (107.1 million tonnes) was utilized fruitfully8.
Major consumption fly ash is occurring in cement. The percentage of PPC in total cement produced has gone up dramatically from 43.17% in 2003-04 to 67.21% in 2009-107. However, Jain has expressed the opinion that the PPC percentage to the total cement produced in India has now saturated and that the same may witness only marginal increase in coming years9. Yet, there is still considerable scope to increase the utilization of fly ash as well as GGBS in concrete, mainly through the RMC route.
Aggregates are inert fillers which constitute around 70-80% mass of concrete. India has been lucky to have good reserves of basalt, granite, limestone, sandstone, etc. However, in recent years, as the concrete volumes have picked up, the concrete industry is feeling the pinch of a shortage of aggregates. The problem is exacerbated in respect of natural (river) sand in view of the dredging restrictions enforced by many state governments and local authorities. In northern India, especially in the Indo-Gangetic plains, river sand had been easily available in the past, but it is now becoming scarce in this region too. Also, in view of the very nature of the alluvial terrain of this region coarse aggregates are not as easily available locally as in South India, forcing concrete producers from North to fetch them from long distances.
With the slated increase in concrete volumes in coming years, aggregates will be required in large quantities. Crushed stone sand (CSS) produced from crushing of natural sand has emerged as a viable and environmental-friendly alternative to river sand and its use should be encouraged from the sustainability perspective.
Further, manufactured aggregates from industrial waste such as copper slag, steel slag, bottom ash from the thermal power plant and recycled concrete aggregates are now permitted to be used in concrete by the Bureau of Indian Standards (IS 383-2016), subject to some upper limits specified in the code. But, considering the fact that most of these sources of aggregates are located away from major construction sites, their use in concrete will be governed by the logistic consideration. Yet, wherever economically feasible, the use of such aggregates augurs well from the sustainability perspective.
Owing to the increasing population, industrialization and urbanization, the per capita availability of water is reducing in India. Further, rainfall is not uniformly distributed and is erratic. There a is a large variation in the rainfall received in different parts of the country Many areas in India are perpetually drought-prone.
Water is required for concrete production and curing in large quantity. Water is also required for washing of truck mixers and central mixer. RMC producers store the wash water in settlement pits/tanks and re-use the clear wash water for concrete production and for dust suppression. Some RMC producers employ a specially-designed Reclaimer system and/or filter press technology, which are capable of separating clear water and suspended solids from the wash water for reuse.
Why RMC is more Eco-friendly than SMC?
As compared to site-mixed concrete, RMC has many characteristics that enhance its environmental-friendly nature. These are briefly summarized as below:
Energy saving: In site-mixed concrete jobs considerable energy is wasted in multiple levels of transportation of concrete ingredients and concrete. With the use of RMC, there would be substantial savings in the overall energy cost used in construction.
Reduction in storage needs at site: With the use of RMC, there is no need to store cement, sand, aggregates, water, admixtures, etc. at construction sites, drastically reducing the space requirements at the site. In a metropolitan area, where there is a premium on space, this would lead to large savings. Further, the contractor/builder need not invest in temporary/permanent structures required for storing different concrete ingredients.
Reduction of wastage: In labour-intensive site-mixed concrete, wastages occur in the handling of all materials, including cement. The latter is generally of the order of 1 to 2 kg per 50-kg bag of cement, and this can be drastically minimized using RMC. Cement is a costly input and any savings in this input will go a long way in minimizing the wasteful use of non-renewable raw materials.
Reduction in public hazards: At a typical construction site in an urban area using site-mixed concrete, the stored ingredients of concrete, more often than not, spill on the footpaths and roads, obstructing pedestrian and vehicular traffic, besides clogging up manholes and drains. Such hazards do not exist on sites using RMC. A construction site using RMC would generally look neat and clean.
Reduction in Dust Emissions
At the RMC plant, relevant technology can be used to minimize dust emissions in accordance with local and national regulations. Ready Mixed Concrete Manufacturers’ Association has evolved dust pollution control strategies to mitigate the hazards of air pollution in a video10. Major features of the dust pollution control strategy include:
A 6-m high peripheral barricade with extended synthetic nets are provided over aggregate bins to suppress dust emission
Cement and other powdered materials (fly ash, GGBS, etc) are received in the RMC plant in closed bulkers and are loaded in silos pneumatically with no spillage or dust emission into the atmosphere.
Silos are fitted with dust filters at the top or bottom with pressure release valves. These filters are cleaned periodically under routine maintenance.
Water sprinklers fitted in the aggregate bins continuously rotate and sprinkle water on the stored aggregates to suppress dust and lower the surface temperature of the aggregates.
The aggregate hopper and conveyors are covered. Conveyor-ends that discharge aggregates into the hopper are covered with tin cladding and flexible plastic sheet to minimize dust emission.
The central mixer is covered and fitted with a filter to contain dust.
Hard concrete pavements are constructed in the entire vehicular area in RMC plants to contain dust generation
The tyres of the loaded transit mixer trucks are washed thoroughly before they are off to construction sites.
Trees are planted in the production sites to further contain pollution.
Why Greenpro Certification for RMC?
Leading Indian ready-mixed concrete producers are already making significant efforts to reduce GHG emissions by adopting a variety of technologies including the increased use of supplementary cementitious materials like fly ash and slag and controlling dust emissions. Yet, ample opportunities exist to improve the “green” performance of a variety of products from the ready-mixed concrete industry. Further, clear-cut guidelines are essential for assessing the “greenness” of concrete. Considering this, the Ready Mixed Concrete Manufacturers’ Association and the Green Products and Services Council (GPSC) of India under the Confederation of Indian Industries (CII) decided to develop Green Product Certification RMC. This initiative is supported by the Quality Council of India (QCI) and the International Finance Corporation (IFC).
The Greenpro certification for RMC is one such initiative by the GPSC. Greenpro for RMC was launched during Indian Green Building Congress held at Jaipur in October 2017.
Objectives of Greenpro for RMC
The main objective of Greenpro for RMC is to facilitate the Indian ready-mixed concrete producers to adopt green measures and to enhance the green performance of their products with the ultimate objective of reducing the GHG emissions of the RMC industry.
The GPSC has estimated that GHG emission reduction to the tune of 150,000 tonnes / annum can be expected on account of reduction in resource consumption during the manufacturing process and increase of additives in ready-mixed concrete.
Salient Features of Greenpro for RMC
For evolving the certification system, GPSC set up an Expert Group. The expert group followed the prescriptive as well as the performance-based approach.
The certification system evaluates the green features of RMC based on eight well-known parameters, namely, product design, product performance, raw materials, manufacturing process, waste management, life-cycle approach, product stewardship and innovations. The certification aims to improve resource conservation through increased use of recycled content (e.g. manufactured/recycled aggregates, fly ash, slag, etc.) enhanced energy efficiency, water efficiency, minimization of waste, etc. by adopting the well-known 3”R”(Reduce, Recycle and Reuse) techniques.
Under the GPSC certification, points (credits) would be awarded on the basis of concrete properties which reduce the environmental degradation. Some of the concrete products which can qualify such requirements include:
Concretes containing higher levels of supplementary cementitious materials such as fly ash, slag, etc., which helps in reducing the requirement of Portland Cement.
Concretes having low densities (e.g. concretes containing EPS, foam, etc.) – the use of which improves the thermal insulation of the building envelop.
Self-compacting concrete, which eliminates the need for vibration during placing of concrete, thereby helping in noise reduction.
High-strength concrete, which has the potential to minimize concrete section sizes, thereby reducing the requirement of the concrete itself.
Pervious concrete having high percolation rate to water, contributing to rain water harvesting and filtration of percolating water.
Many others helping to reduce the GHG emissions.
Incidentally, it may be pointed out that the first two requirements mentioned above are in line with the sustainability tools suggested by the well-known concrete technologist, Prof P K Mehta described in earlier paragraph4.
Considering the fact that the sources of good quality aggregates are depleting fast in different parts of India, the GPSC certification encourages the use of alternative sources of aggregates such as aggregates from steel, iron and copper slag, bottom ash from the thermal power plant and recycled concrete aggregates. Such use is, of course, subject to the condition that the requirements specified in IS 383 dealing with aggregates for use in concrete are followed and that such variety of aggregates are sourced from closer and economically viable distances.
Under the RMC manufacturing processes, the following aspects have been carefully considered:
Energy efficiency: Reduction in specific energy consumption
Water efficiency: Reduction in specific water requirement
Particulate emission reduction: PM 10 and PM 2.5
Concrete Sludge Management: Reduction in the quantity of waste generation
Renewable Power: Use of on-site and off-site renewable sources for meeting energy needs
Product Stewardship: Includes education of stakeholders, QMS for measuring rejection rates and extended product responsibility
Innovations: Recognize initiatives that are not addressed in this certification but which have a profound impact on protecting environment.
For the product to be taken up for Greenpro certification, the RMC producer needs to comply with the following requirements:
- Factory license under the Factories Act for permission to operate the plant
- Valid consent to operate under the Water (Prevention & Control of Pollution) Act & Air (Prevention and Control of Pollution) Act
- Valid authorization under the Hazardous Waste (management, handling & transboundary movement) Rules
Occupational Health & Safety compliance as per the norms of Developed jointly by the National Safety Council of India (NSC) and RMCMA.
Minimum Equipment and Systems Requirements:
For getting the Greenpro certification, the RMC plant needs to have a valid RMC Capability Certification from the RMCPCS scheme spearheaded by the Quality Council of India (QCI). If such certification is not available, the CII team will carry out an audit of the plant to ensure compliance with the major features of the QCI certification scheme.
The Greenpro evaluation will be done by a third-party conformity agency appointed by GPSC. The products will be certified based on the credit points achieved during the evaluation. While the maximum achievable credit points are 100, the product and the plant supplying the product will be certified as a green product, based on certain minimum points earned during evaluation. Incidentally, the RMC Plant supplying the Greenpro-certified product needs to satisfy all mandatory requirements mentioned above.
RMC Plants from Godrej Honoured with the First Certification
Godrej & Boyce Mfg. Co. Ltd. were amongst the first RMC manufacturers to offer their plants for certification under Greenpro RMC. Godrej offered three of their plants –Vikhroli, Mumbai; Ambernath, Thane district and Dhayatri near Pune. The process of the audit of these plants commenced with the training of some 18 personnel of Godrej in October 2018, culminating in the certification of their first plant at Vikroli in November 2018. During the Green Building Congress held at HICC, Hyderabad in November 2018, the Greenpro RMC Certificate was received by Mr. Anup Mathew, Senior Vice President & Business Head, Godrej Construction from Mr. Tuyen D. Nguyen, Principal Operations Officer, Manufacturing, Agribusiness and Services, International Finance Corporation (Fig 4). After completion of the audits of the two remaining plants from Godrej, these plants have also been awarded the Greenpro RMC certification recently.
It is understood that certain plants belonging to Ultratech Cement Ltd. and ACC Ltd. have applied for certification under Greenpro RMC. More RMC producers are expected to join this cause.
The ready-mixed concrete industry in India, which has been growing steadily during the past, is slated to grow further in near future. While the leading RMC producers from India have already taken many green initiatives, ample opportunities exist to further improve the “green” performance of the RMC industry’s products. The Greenpro certification is a good tool for this purpose. The use of this tool will go a long way in enhancing the green performance of the products from RMC industry and will also help in achieving the ultimate objective of reducing the GHG emissions from the industry
- “Climate Change 2014 Synthesis Report Summery for Policymakers” Based on Fifth Assessment Report (AR5), Intergovernmental Panel on Climate Change (IPCC), 2014 p. 32.
- “Global Warming of 1.50C” Summery for Policy Makers, Intergovernmental Panel on Climate Change, Printed October 2018 by the IPCC, Switzerland.
- “India most vulnerable country to climate change – HSBC report”, https://www.reuters.com/article/us-climatechange-hsbc/india-most
- Mehta, P.K., “Global Concrete Industry Sustainability”, Concrete International, February 2009, pp. 45-48.
- “Glorious 100 years of cement industry 1914-2014” Survey of Cement Industry and Directory 2015, 4th edition, Industrial Chronicle, Hyderabad.
- Cement Sector, Report of Nirmal Bang Institutional Equities, March 26, 2018.
- Report of the Working Group on Cement Industry for XII Five Year Plan, Department of Industrial Policy and Promotion, Ministry of Commerce and Industry, December 2011.
- Report on Fly Ash Generation and its utilization in the Country for 2016-17, central Electricity Authority, New Delhi December 2017.
- Jain A K (2010), Fly ash utilization in Indian cement industry: Current status, future prospects, Seminar on Concrete Sustainability, Indian Concrete Institute, pp.46-51.
- Guidelines on Pollution Control Measures, Ready Mixed Concrete Manufacturers’ Association, http://www.rmcmaindia.org/ environment.html
Mr Vijay Kulkarni is currently the Partner with Midas Techfin Consultants LLP. He is the Head-Technical Committee, Greenpro Certification for RMC by CII. Formerly, Mr Kulkarni was the Principal Consultant, Ready Mixed Concrete Manufacturers’ Association (RMCMA), India. He was the Past President of the Indian Concrete Institute (ICI). Presently, he is the Chair of ICI Committee on Concrete Durability and Co-Chair of ICI’s Technical Board. He is the Member of the Technical & Sustainability Committees of the European Ready Mixed Concrete Organization (ERMCO) and also of the BIS Committees on Cement and Concrete. He has published around 60 technical papers in national and internal journals/magazines/ seminars/conferences. Mr Kulkarni is the recipient of the Outstanding Concrete Technologist award from ICI and the best paper awards from both IRC and ICI. Earlier, Mr Kulkarni was the Editor, The Indian Concrete Journal (ICJ).