THE INDIAN EXPERIENCE OF READY MIXED CONCRETE (RMC)

Transcription

1 THE INDIAN EXPERIENCE OF READY MIXED CONCRETE (RMC) C. R. Alimchandani*, STUP Consultants Ltd., India 32nd Conference on OUR WORLD IN CONCRETE & STRUCTURES: August 2007, Singapore Article Online Id: The online version of this article can be found at: This article is brought to you with the support of Singapore Concrete Institute All Rights reserved for CI Premier PTE LTD You are not Allowed to re distribute or re sale the article in any format without written approval of CI Premier PTE LTD Visit Our Website for more information

2 32 nd Conference on OUR WORLD IN CONCRETE & STRUCTURES: August 2007, Singapore THE INDIAN EXPERIENCE OF READY MIXED CONCRETE (RMC) C. R. Alimchandani*, STUP Consultants Ltd., India Abstract Although the first RMC plant operated in India in 1987, the growth of RMC has picked up only in the last decade. Most of the RMC plants are located in 7 large cities of India, where they contribute 30% to 60% of total concrete used in these cities. RMC, on all India basis contributes to about 5% of total concrete used. The growing popularity of RMC in cities is for obvious reasons of constraints of construction space and need to control environmental pollution. This is in spite of about 12% to 20% higher cost as compared to site mixed concrete. The number of RMC plants in India, are growing rapidly and being relatively new ones having most up-to-date machinery and technology. The detailed information given in the paper is based on data collected by 7 large offices of STUP Consultants P. Limited in India where they are actively recommending the use of RMC in many major projects in all fields of Civil and Engineering and Architectural applications in essence to obtain better quality of work.. Keywords : Ready Mix Concrete, environmental pollution control, space constraints at site concreting in large cities, India, growth of RMC. Fig 1 : Subway at Pune picture of one of the entry ramps to the main subway

3 The first use of RMC took place in the city of Pune in 1987 but they did not have transit mixers and they could not supply agitated concrete at the speed required for the Tanaji Wadi subway, which had a very wide bottom slab and high retaining walls. RMC could not be used by us and the RMC unit made efforts with others, but failed to satisfy and closed down. RMC has, however, grown modestly during the last decade. One of the main reasons for this lack of growth of RMC in India lies in the construction practices followed in the country, which are traditionally labour-intensive. Even today, a substantial proportion of concrete produced in the country is volumetrically-batched and site-mixed, involving a large number of unskilled laborers in various operations. The situation is however, slowly changing and a trend in favour of mechanization/semimechanization in construction is clearly discernible in the urban centers. It is therefore logical that most of the RMC plants are concentrated in these centers. RMC has helped in creating and boosting the demand for bulk cement. In fact, both are mutually complimentary and nurturing RMC would go a long way in modernizing the construction sector. Besides, both are today considered to be eco-friendly practices as they have the ability of minimizing wastage of raw materials and reducing pollution. On the other hand, being late starters, RMC producers in India have the advantage of adopting the latest-generation plant and equipment, and many of the RMC facilities in India have state-of-the-art plants, with sophisticated micro-processor based controls having ability of accurate weighing and batching, automatic charging, adjustments for moisture compensation, inventory control, etc., besides having a fleet of transit mixers of various capacities, most of these plants possess well equipped facilities for pumping concrete. Fig 2 : Geographical spread of STUP Mumbai To get a clear and up-to-date picture of what is happening in the seven most important urban centers of India, where our large offices are located (I leave out 8 smaller offices in India and larger offices in the Middle East, Europe and the USA, because these are not relevant to this presentation), I have collected information on the present status of use of RMC versus total concrete used in these cities. The yellow indicates where we have worked in the world since we were founded at Mumbai in as a centre of excellence for Asia and Africa in Prestressed Concrete. During the same period we have diversified to try and reach excellence in every field of Structural, Civil Engineering and Architecture and we have grown to a size of 1400 persons all searching for Excellence. Please forgive me for speaking about my company at OWICS for the first time in 3 decades the object of giving these details is to indicate that we have tried to cover the use of RMC in these 7 major cities in all the disciplines in which we are working.

4 In Delhi, capital of India: Fig 3 : Transit Mixer pours RMC into a concrete pump Fig 4 : Two Transit Mixers pouring RMC simultaneously The percentage of RMC to total concrete being used is 28.5%. RMC is being used for bridges, flyovers and large commercial and residential buildings. The total volume of RMC used per year from 9 plants operating in Delhi is 1.56 million cubic meters. Several big projects have their own Batching Plants and Transit Mixers and the aggregate volume produced per annum from the same is difficult to quantify and has, therefore, been left out. The price of RMC is in the range of US $ 90 to US $ 100 per cu.m. The price of concrete from onsite Batching Plants for large projects is in the range of US $ 82 to 90 per cu.m., i.e. 9% to 10% cheaper than RMC.

5 RMC plants are situated in the suburbs of NOIDA and GURGAON and transit time is less than 1 hour for concrete supplied within these suburbs. While for the main city, RMC is supplied mainly at night due to day time traffic restrictions and the average transit time has become one and half to two hours, even at night. Our Delhi office considers that RMC is a success in Delhi, in spite of the extra cost compared to site mixed concrete mainly because of space constraints at urban sites and also because of reliable quality, speed and volume of supply of RMC. At Ahmedabad the capital of the state of Gujarat Fig 5 : Loading aggregate into a hopper which will feed it to a conveyor leading to a mixing plant 90% of the concrete used is RMC for multi-storey commercial complexes and bridges due to shortage of space for onsite Batching Plants. Fig 6 : Loading a Transit Mixer at the RMC Plant The total RMC used is 0.5 million cu.m. per year. The cost of RMC was US $ 67 per cu.m against site batched concrete which was US $ 55 per cu.m. i.e % cheaper than RMC.

6 The average transit time is 45 to 60 minutes, and can vary due to traffic problems by 30 to 60 minutes. The rate of increase in demand is naturally slow and will increase only as per the quantum of supply when the building industry resorts to RMC. At Mumbai, Capital of the State of Maharashtra which is as large a metropolis as Delhi or Kolkata: Fig 7 : A RCC Girder cast by RMC being erected at the Mithi River Fig 8 : PSC Girders being stacked at the precasting yard The total quantity of RMC used in Mumbai last year is 1.5 million cu.m. of concrete. This represents 60% of the concrete being consumed at Mumbai for major road and flyover projects. The average transit time at Mumbai is 4 hours during the daytime. The traffic situation is 350 to 400 vehicles a day in Mumbai. The Mumbai Metropolitan Region Development Authority is considering going to court for staying the plying of the new US $ 2500 car which is going to be produced very soon by TATA Automobiles, as the same will lead to a catastrophic rise in congestion in the city of Mumbai. At present a wide variety of concretes are being manufactured : High Strength Concrete, High Performance Concrete, Self Levelling Concrete, Fibre Reinforced Concrete. The aspect of reliability, quality and speed of supply makes for RMCs success, so far.

7 At Bangalore, capital of the State of Karnataka. Fig 9 : Construction of Flyover near Bangalore Airport There are 34 RMC plants producing about 2.6 million cu.m. of RMC per annum. This represents 60% of the concrete consumed per annum. Fig 10 : A Friction Slab being fed with concrete by a transit mixer in the background Cost of RMC is 20% higher than that produced at site by mixing machines and 12% higher than that produced at site by large Batching Plants. RMC is used in major infrastructure projects as well as residential buildings and even in the construction of minor culverts RMC is very successful at Bangalore, and the existing 34 RMC plants are unable to cope with the rising demand. Transit Mixers take 30 to 60 minutes to travel 15 km. RMC is successful in spite of increased cost because they deliver fast and supply a reliable quality of concrete.

8 RMC is more used when large scale concreting is involved and placement of 30 cu.m. per hour of concreting maintaining high quality is possible. For smaller pours where a concrete pump is not involved site produced concrete is preferred. The other advantage of RMC is, that, of course, space and security for storage of large and fine aggregates and cement at site are eliminated. The reason why Bangalore is ahead of other Indian Cities, is the large volume of construction in the I.T. Capital of India and therefore the excellent exposure of Business and Government with the world, including a special attachment to Singapore. At Chennai, capital of the State of Tamil Nadu. Fig 11 : Airport Road Flyover The total quantity of RMC used is 80% for industrial, residential and major bridge and flyover projects, and the price of RMC varies by approximately 5% to 10% more depending on the mix of concrete used. Fig 12 : Airport Road Flyover

9 Fig 13 : Kathipara Flyover The average transit time for transporting RMC from the plant to the site is 2 to 3 hours as the traffic is less. RMC is a success in Chennai as quality can be ensured at the Batching Plant as well as reduced involvement of labourers, in this busy city where there is a shortage of labourers. The increase in demand of RMC beyond the estimated 1 million tons, is expected only if large individual residential buildings resort to RMC. At Kolkata, capital of the State of Bengal. Fig 14 : Box Girder stacked in the stacking yard The total quantity of RMC used is between 30% to 35% per annum and the volume of RMC used from seven Batching Plants of varying capacities of 30 cu.m per hour to 90 cu.m. per hour is 1 million cu.m. per annum. RMC is being used in Kolkata city for major buildings. However it is being used for major bridges outside Kolkata. Total capacity of the seven Batching Plants is about 1 million cu.m per annum. The price of RMC is approximately US $ 102 per cu.m. against US $ 78 per cu.m for concrete from onsite Batching Plants. The price includes transportation US $ 0.28 per km. The Batching Plants are located in the suburbs of Kolkata, Sonarpur and Rajarhat and one plant in Dankuni catering mainly for the twin city of Howrah and to some extent to the northern fringe of Kolkata. The average transit time is approximately 1 ½ to 2 hours during the day.

10 Fig 15 : Second Vivekananda Bridge Tollway Project Our Kolkata office considers that RMC is reasonably successful but expects that RMC will cater to 50% of the total requirement in Kolkata in a decade. While you can see a healthy growth in the above urban centres totaling about 8 million tons per annum, our cement consumption is about 110 million tons per annum and India is the second largest consumer of the same in the world, we are expected to close the gap with China in the next two decades. The total volume of RMC used is about million cu.m. per annum all over India. The average transit time is 2 to 3 hours. You may note that only 5% of the total concrete consumed in India is RMC. Generally RMC is a success in the Urban centers where the same is produced. Part of extra cost is compensated by reduced labour and increased speed. Variability of time is a source of dis-satisfaction, yet it is much better compared to delays at site due to shortage of cement supply, space, labour, etc. Standard and Poor states that India will be the second largest economy in the world by Dr Abdul Kalam, our immediate past President has written a well informed book saying India will be a developed country by 2020, and more recently, while he was President, he said, because of the 4 eminent economists running the country he expects we will reach this status earlier. In this century we will become the world s largest economy, because of our being able to stabilize our 1.6 billion persons as compared to China, which will stabilize around a population of 1.2 billion both near the middle of the century. An American Economist once spoke to our Main Rotary Club at Mumbai and said if the last century was a century of America the current century will be one of India. Another French Economist had a breakfast meeting with the objective of arousing the interest of French Businessmen to do business with India, and he said you would be seeing, in the next 3 decades, a country transforming into a hundred cities like Singapore are all these sayings going to come true? I will not be alive when they do.