GREEN CONSTRUCTION AND MAKING CONCRETE "GREEN "
Anil Kumar Pillai, AGM - Technical Services , Madras Cements Ltd, Chennai
Madras Cements Ltd (MCL) , the flagship company of the RAMCO group has interests in cement, cotton yarn, software systems, fibre cement products and wind energy. It is one of the largest cement companies in India with a capacity of 12.49 million tonnes per annum . The Company has taken initiatives in introducing the latest technology in cement plants and also has initiated number of environmental friendly measures at its Plants . The company also has wind energy capacity of 159.19 MW. The Ramco wind farm has a total of 229 wind energy generators and is the biggest in Asia. The Alathiyur plant of the Company has also been recognized as the "greenest cement plant" in the country by the Delhi based Centre for Science and Environment (CSE), which has awarded it "4 LEAVES" as part of its Green Rating Project. Madras Cements is the first and the only cement company to get such a rating in India. Madras Cements is the first company to bring more than half a dozen new technologies and they include: surface mining technology for limestone mining, vertical mills for cement grinding, fuzzy logic software system for process controls, pre calciner technology, most modern programmable logic controllers (PLC), advanced x-ray technology for quality control, highly effective ESPs and bag filters for dust control as well as enterprise mobile computing for business processes. The adoption of the state of the art technologies has enabled Madras Cements to be an energy efficient company.
RRDC (RAMCO RESEARCH DEVELOPMENT CENTRE) the Company has a Research Centre at Chennai where modern test equipments are available for testing cement and concrete. The Research Centre apart from analyzing cement samples also is involved in conducting concrete trials for various grades. There are many concrete trials done at the Research centre for various customers with various chemical admixtures to study the compatibility.
World Environment day is celebrated on June 5th every year. The Construction Industry in India due to its large scale generates lots of wastes which is capable of recycling. In order to avoid global warming many countries are taking initiatives so that the activities which enhance their growth is also environment friendly . Any activity in construction that fulfils the requirement of durability and sustainability is environment friendly. The stake holders in this movement are the builders , the Consulting Engineers , Architects and the building material manufacturers like cement ,aggregates, chemical admixtures , Ready Mix Concretes etc .
IGBC 'S definition of a green building
In India CII's Indian green Building Council has been taking lot of initiatives in promoting the concept of green buildings. Green Building defined as per IGBC ( CII) is "A green building is one which uses less water, optimises energy efficiency, conserves natural resources, generates less waste and provides healthier spaces for occupants, as compared to a conventional building. " Any building can get themselves green rated based on the rating system of LEED (Leadership in Energy and Environmental Design) .
High resolution Photograph of Alathiyur Plant would be given by Shashank Sharma
Alathiyur Plant of Madras Cements Ltd which has won the Four Leaves Award
Why green buildings :
India as a country has the potential to grow and therefore to develop the infrastructure green buildings have become necessary . Reasons for encouraging the green concept in construction industry are as follows:
1. Populations will continue to increase
2. Infrastructure needs will grow in order to provide for the basic needs of the increasing population
3. Natural resources are limited. The mineral resources (limestone and aggregates) and non-renewal energy necessary for cement and concrete productions are becoming scarce
Hence there is an urgent need to reduce the "green house" emissions, particularly carbon dioxide (CO2) to combat global warming
Concept of green in construction :
The green concept in any construction starts from the planning stage to design to implementation stage.
In the design stage environmentally sustainable design could be listed as follows:
1. Orientation of building could be in a way so as to maximise incident solar energy .
2. Ensure Ventilation to reduce utilisation of energy
3. Use of renewable electricity generation through Photovoltaic cells
4. Insulation in buildings to prevent migration of energy
5. Rain water harvesting
6. Water efficient appliances and fittings.
CONSTRUCTION &DEMOLITION WASTES
It is estimated that 1 billion tons of construction and demolition (C&D) waste are generated annually worldwide. Utilization of such waste by recycling can provide economic and environmental benefits. In recent years, utilizing C&D waste for new construction through recycling and reuse has received increased attention throughout the world, especially in the European countries, Japan, U. S., and Taiwan.
Practical and economic experiences from Japan and Denmark suggest that road base and sub-base materials are expected to be the most important area of use of C&D waste
GREEN CONCRETE
Concrete can be made green by making it durable and sustainable . As remarked by Prof. Adam Neville " It is now known that or many conditions of exposure of concrete structures , both strength and durability have to be considered explicitly at the design stage . The emphasis is on the word "both" because it would be a mistake to replace overemphasis on strength by overemphasis on durability "
Durability in concrete structures:
If concrete structures are made durable there could be large savings in natural resources and energy The most significant incorporation of the Roman's was the use of pozzolan-lime cement by mixing volcanic ash from the Mt. Vesuvius with lime. Best know surviving example is the Pantheon in Rome. As per IS 1489( Part 1 ) : 1991 - Portland Pozzolona Cement produces less heat of hydration and offers greater resistance to the attack of aggressive waters than normal Portland cement . Moreover it reduces the leaching of Calcium hydroxide liberated during setting and hydration of cement . It is particularly useful in marine and hydraulic construction and other mass concrete structures.
Curing is essential for maintaining durability in concrete . There has been advances in curing Internal curing has been defined by the American Concrete Institute (ACI) as "supplying water throughout a freshly placed cementitious mixture using reservoirs, via pre-wetted lightweight aggregates, that readily release water as needed for hydration or to replace moisture lost through evaporation or self-desiccation"
High Performance concrete
As mentioned in literature high performance concrete does not mean high compressive strength alone. It also means fulfilling other desirable properties in concrete like adequate workability and durability . More recent developments in the use of high-performance concrete, low permeability, concrete mixtures, proper use of air-entrainment, epoxy-coated reinforcement, protective coatings, and corrosion-reducing admixtures have greatly increased the service life of concrete.
High Performance concrete will play a vital role in reducing the environmental degradation since making high performance concrete essentially means optimising the use of ingredients of concrete by measuring the concrete parameters and installing the required quality assurance measures at sites.
Concrete at site should not be evaluated on the basis of prescriptions but performance is the criteria . Ready mix concrete at site is normally checked on the basis of performance but there are customers who also put limits on the quantity of constituent materials . One cannot have both prescriptions and performance in view of the variability of the materials used .
Life Cycle Cost approach :
Decisions relating to planning and implementation of projects are done on the basis of initial costs alone . This is not the right approach for costing a project .
Life-cycle cost approach should be considered by the owners by seeking a better and durable concrete structure rather than lower initial cost.
Life cycle Cost approach will help in finalising materials for concrete which fulfils the criteria of durability and sustainability
Extending Service Life of Existing structures
Extending the service life of the existing infrastructure (instead of removal and rebuild) through periodic inspection, evaluation, proper maintenance, and appropriate repair not only requires less natural resources and energy but also minimizes environmental impacts..
Corrective and Preventive Maintenance :
"Both corrective maintenance and preventive maintenance are essential. This may be unpalatable to some people but it is not really surprising: all construction materials,as well as all natural materials, which are subjected to moisture or to temperature variation deteriorate. In the fullness of time, rocks disintegrate and so will concrete, however good. Maintenance ensures that concrete does not do so in our lifetime or that of our children" ( As quoted by Adam Neville in Consideration of durability of concrete structures: Past, present, and future , Materials and Structures/Vol. 34, March 2001, pp 114-118 )
Practical measures to be implemented at site for green concrete :
Mix Design :
Concrete Mix Design will help in optimisation of constituent materials for concrete . Nominal Mixes is uneconomical and sometimes excess cement may lead to shrinkage cracks in concrete . There is a perception that usage of excess cement will enhance the quality of concrete . Due to insistence from the client masons and contractors use excess cement in concrete which will deteriorate the quality of concrete structures. As per Mehta PK ( 2002) in his article Greening of the concrete industry for sustainable development , the concrete industry also uses significant amounts of water and aggregates and is in total the largest user of natural resources in the world.
Use of Blended Cement :
Use of Blended cement like flyash based Portland pozzolana cement will help in densification of the cement paste, lower heat of hydration .Usage of flyash in concrete is not a new phenomenon and its usage can be traced back to 1930's where its having a history of giving durability and structural benefits.
Measure of Durability :
Durability in concrete structures should be measured through RCPT test ( Rapid Chloride Penetration Test ). Depending on charge passed durability of concrete structures could be evaluated. The measure of durability if implemented at site will help in promotion of durable concrete .
Practices like Effective Curing :
Effective curing is being done for slabs. However curing is also be done effectively for vertical structural members like columns where curing is more dependent on people spraying water.
Practices like effective curing will ensure durability of structures but the challenge is implementation of this practice especially during hot summer season .
Formwork removal :
Whenever formwork has to be removed quickly the required quality control measures and testing arrangements should be available at site. Without these measures quick removal of formwork can lead to deterioration of structures . There are concrete technologists who suggests that formwork will have to be left in place for ensuring water does not escape from concrete surface.
Indian Cement Industry with Modern Cement Plants with Latest Technology and Energy Efficient Plants
- On the energy front the cement industry has proactively responded to the initiatives of Bureau of Energy Efficiency ( BEE) which comes under the Ministry of Power in improvement of and reduction in energy consumption norms for cement sector .
- Some of the Plants have become global benchmark in energy consumption second to Japan
Carbon Credits :
In the Summit hosted by Kyoto, Japan - 1997 targets for reduction of greenhouse gases emitted by the industrialized countries were set. Clean Development Mechanism ( CDM) provides a commodity ( GHG /carbon equivalent units) and aims to provide mutually shared benefits for investors and host . Developed countries funding projects for reducing emission targets in developing countries thereby receiving credits for the same is a concept which will give impetus to greening of the construction industry .
A global trade in flyash has the potential to reduce Green house gas emissions embodied in concrete, if the flyash is used to reduce the consumption of Portland cement per cubic metre of concrete ( Impact of flyash content and flyash transportation distance on embodied greenhouse gas emissions and water consumption in concrete - Kate R.O'Brien, Julien Menache, Liza M.O’Moore 2009 )
The concept of green buildings is getting more acceptance in the Indian Construction industry . The LEED ratings of many buildings in India is a reflection of this phenomenon . Carbon credits is expected to become more common and it is expecting that trading in carbon credits would increase in future.
Anil Kumar Pillai BE ( Civil ) , EMBA , MBA , PGDCM , MIMA , MIE
AGM - Technical Services , Madras Cements Ltd, Chennai