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June, 1999 LIVING in the age of increased specialisation demands a critical examination of various techniques and materials from time to time to adopt better technological alternatives wherever possible. Ready Mixed Concrete (RMC) is one such item that needs to be brought to the centre of Indian construction scene if the desired parameters of quality progress and durability are to be achieved. Though RMC is a household term abroad, it is yet to make a significant mark in India. Somehow the Indian engineers have been ignoring this item and putting conventional concrete production methods in the front seat. The present circumstances reveal that the pace of development coupled with better quality in construction can be maintained only if we switch over to RMC now and in a big way by the turn of the century. Ready Mixed Concrete is concrete that is prepared and supplied to construction sites in a plastic, unhardened and ready to use state. The consumer avoids all sorts of burden of procurement of various aggregates, cement, plant and machinery. Above all, a strict quality control can be ensured at the RMC station. The batching and mixing of different ingredients is done at a central batching and mixing plant. Final mixing is done in the truck-mounted transit mixers which carry the concrete to the site of its pouring. Though the batching plants are used at many project sites to produce the required quantity of concrete, the concept of RMC is different. The batching plants established at project sites are on temporary basis and cater to the needs of the project with respect to certain defined mix-designs. Many times these plants are manually operated or semi-mechanised and inherit a number of errors. A RMC station is established permanently in a city or town where the consumers lodge their concrete requirements along with the mix-designs and concrete is supplied to different locations as per given requirement and mix. A RMC station has a computerised and fully automatic arrangement for batching and mixing of ingredients. As many as 100 mix-designs can be stored under the RMC computerised control and concrete can be prepared for any of these mix designs. The consumer may be anyone, a government department, a private firm, a building contractor or even an individual. The batching and mixing plant of a RMC station are provided with various attachments such as loading and unloading screws, inclined belts, extraction belt, scales for weighing aggregates in batches — all provided to simplify the operations. The capacity of RMC station may vary from 15 to 150 cu.m. of concrete per hour depending upon the demand of concrete. Each RMC station maintains a fleet of transit mixers required to transport ready mixed concrete to various sites. The capacity of each of these mixers may vary from 4 to 7 cu.m. per hour. Concrete can be delivered to places as far as 20 km from the RMC station. Even a larger distance can be contemplated. Response That RMC will receive enough response in India, if marketed as a commercial product, can be assumed from the fact that when such a station was established near Bangalore in 1998, a number of enquiries for supply of concrete were received by the RMC station owner even before its commissioning. Within two months of its commissioning, the RMC station supplied more than 3500 cu.m. of concrete to various sites though many didn’t yet know about the existence of the plant. A survey of construction scene across the globe shows a total transformation from conventionally followed manual and semi-mechanised methods of concrete production to fully automatic and computerised ready-mixed concrete production. Today, USA is using 70% of its annual cement production in ready-mixed concrete through its 3700 RMC plants. India, as on date has just 17 such stations, most of which are established to meet the personal needs of Indian builders or for infrastructural project concrete requirements. Use of RMC as a commercial product is missing. Another interesting thing to be seen is that while Mumbai has 8 such stations followed by Bangalore with four and Calcutta with two. There is not even one ready-mixed concrete station in the capital. Advantages If we begin to enlist the advantages of Ready Mixed Concrete, there are many. RMC provides a solution to the ever lingering thought, ‘how to ensure quality in practice rather than doing just a paper-exercise’. Some advantages that immediately come to mind are: 1. Total automation of material-batching and weighing, thus eliminating over-batching or weighing of materials. 2. Admixtures get added to concrete with high accuracy. 3. Cement saving of 15 to 25 kg per cu.m. of concrete is achieved due to better control. 4. Accurate measurements result in a reduction in standard deviation thus reducing cost factor. 5. Pilferage of material, so much associated with construction works, gets eliminated. 6. There is a significant reduction in wastage of materials and labour. 7. Quality control to a very high degree. Flyash utilisation The most promising advantage of RMC to my mind is the large-scale utilisation of flyash because of its best blending with other materials in a RMC plant. Flyash is increasingly becoming an environmental hazard and its utilisation in concrete is essential to maintain to ecological balance. Economy achieved due to saving of cement is additional advantage. The problem that engineers have been facing is that flyash doesn’t get fully mixed up with concrete ingredients. At RMC stations, dispersion of flyash within concrete is not at all a problem even in concrete with high slump values. A private builder in India established a RMC plant for his building projects and used flyash in concrete. He found the consistency and strength of flyash concrete better than conventional concrete even for concrete of grade as high as M45. He went ahead with the use of flyash concrete in his works and by today, his RMC station has produced more than 1,00,000 cubic m of concrete. Could there be a better example than this to shun all our fears over flyash utilisation in concrete? The only requirement is a thorough mixing of flyash with concrete which is easily possible at RMC stations. Of course the other guidelines as laid in IS codes are to be followed as usual. Bottlenecks Why RMC has not taken off in India? What are the bottlenecks? Analysis shows that we are habitual of toeing the line and accept new developments with great caution even if these are beneficial to us. Another factor has been that Indian construction industry has been highly labour-intensive. The scene has changed now. Most of the skilled labour has shifted to Middle-East, looking for better avenues and labour is no longer cheaper in India. The only bottleneck in real terms is the initial investment required to establish a RMC station. This needs to be given a careful thought by the industrialist as well as the government. While the industrialist should rest assured that the future belongs to RMC and should go ahead to diversify or invest in this field for rich gains, the government too should offer concessions, excise-free and sales tax-free holding to RMC-industrialists. To usher RMC in — a sure route to quality and economy — the following steps should be taken: 1. Use of RMC should be specified by the government departments for all the major power, irrigation and other infrastructural projects. 2. Special concessions should be announced for RMC industry. More emphasis should be laid over setting of RMC stations for commercial supply of RMC just like any other commodity. 3. In the construction-industry seminars held from time to time, the industrialists should make commitment to invest in RMC industry. 4. Bureau of Indian Standards, who showed great “efficiency” in drafting an IS code on RMC in 1976 should revise it with respect to the present construction scene and should add guidelines for supply of RMC as a commercial product.
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