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Reliance on past methods and the drive to earn profits have often led to a compromise by the construction industry on the basics of safety, quality, economy and speed, says Er. JAGVIR GOYAL. Modern practices and non-destructive concrete testing coupled with the use of RMC, flyash bricks, and admixtures and compounds is the way forward. Economy, Quality, Progress and Safety: Four crucial parameters that need to be weighed precisely while taking decisions over the specifications for each component of a structure. But reality is far from this. A close look at the construction practices being adopted by individuals in residential construction as well as by government departments, which execute the major chunk of development works, tells a different tale. Quality and safety are often relegated to the bottom rung of priorities. There is a lot of hesitation in switching over to new materials as engineers lack faith in them. In addition, engineers lack the initiative to study and try new techniques, which, if adopted, could lead to more sound and economical structures. Many a time, the tendency to earn profits by compromising over the soundness of structural components that get hidden under an attractive façade prevails among builders. The Mason's Dictum Despite the construction industry having entered a revolutionary phase, the mason's dictum still continues to prevail. Computer-Aided Design (CAD), efficient and versatile machinery, highly sophisticated equipment, varieties and grades of concrete and cement and steel and eco-friendly substitutes to conventional materials are playing a pivotal role in changing the construction scene around the world. Yet, in many places in India, the old and traditional line is still being toed. The result? Wastage, leakage, cracks, dampness, efflorescence and termite attacks. All this necessitates an urgent need to view current practices and find the appropriate alternatives. Cement Content of Concrete Better strength of higher grades of cement and remarkable improvement in the technique of cement production necessitate a review of the minimum cement contents prescribed by various consultants and government departments in the concrete specifications laid down by them. It is also required to define new grades of concrete with respect to the grade of cement being used. According to assessments, if concrete grades are redefined and 'minimum cement contents' are reviewed and revised, an annual saving of Rs. 25000 million can be effected in India alone. The introduction of 33, 43 and 53 grades of cement has made the job of choosing the grade of cement easier. Experimentation has shown that there is ample scope to save without compromising on the strength or durability of the concrete. Thus the urgent need to redefine the minimum cement contents for each grade of concrete and further with respect to each grade of cement cannot be ignored. RMC and Hand Mixing Often Indian specifications in place even allow hand mixing of concrete, which does not produce a desirable blend of concrete ingredients, consumes more cement and does not ensure the control of the water-cement ratio. On the other hand, RMC (ready-mix concrete), a household term abroad, is yet to make a significant mark in India. Prepared and supplied to construction sites in a plastic, unhardened and ready-to-use state, with the use of RMC, the consumer avoids the burden of procurement of various aggregates, cement, plant and machinery. Moreover, strict quality control is ensured at the RMC station. In fact, RMC needs to be supported by the Government in terms of excise and tax concessions since it is a sure route to quality and long-term economy. It should be promoted on a large scale, while hand-mixing of concrete should be wiped off the Indian construction scene. Reinforced Brick Roofing The provision of reinforced brick (RB) roofing in houses is a practice often followed in India; this type of roofing has been more common than the strong, impervious and economical RCC. According to a survey, this is because people tend to follow whatever the mason suggests, and also because of the misconception that RCC roofing develops cracks while RB roofing does not. It is time for a rethink. RB roofing has bricks laid on edge and covered with a 40 mm. thick layer of concrete. Reinforcement is laid in gaps left between the bricks. A bottom cover of 12 mm. to the reinforcement means a slab thickness of 167 mm. The brick-laying arrangement decides the spacing of the reinforcement. On the other hand, RCC roofing can be just 113 mm. thick; its reinforcement spacing is decided by the designer and it is more economical than RB roofing. Brick masonry has a permissible compressive strength of 2.5 N/ sq. mm., while M15, the lowest grade concrete, has a strength of 15 N/ sq. mm. The only factor that goes in favour of RB roofing is the low thermal conductivity of bricks, which may help in lesser expansion of slab and better insulation to heat. However, this factor should be weighed against the drawbacks of this type of roofing. If proper end treatment is given to RCC slab by providing an 8 mm. gap at its end, filled with asbestos filler and a 10 mm. bearing plaster, no cracks would appear. The problem of efflorescence too occurs only in RB roofing. Thus, the practice of using RB roofing should be stopped; only RCC roofing should be used. Use of Bricks In fact, conventional bricks suffer from high porosity and low strength; the use of flyash in bricks can eliminate this. Flyash can be used in combination with clay or with lime and sand to produce clay-flyash bricks and flyash-sand-lime bricks. An actual experience in the use of clay flyash bricks shows that these may help in considerable increase in the utilisation of flyash and would provide really strong and efflorescence-free bricks to the end user at a competitive price. Keeping in view the better test results of clay flyash bricks, one should switch over to them by revising work specifications and adding the items of brickwork in clay flyash bricks to tender documents. Government departments should declare it compulsory to use only flyash bricks in all public works. Testing of Structures Through the years, scientists and engineers have kept themselves engaged studying concrete's behaviour and reaction with other materials so as to make it more economical, strong, durable and compatible with other materials. At the same time, it has been played with, tempered with and downgraded in quality to satisfy the greed of those with vested interests. A major handicap in the past has been the inability to test it to be as per specified parameters without destroying it. Now, many tests and instruments are available that can check the strength, soundness or even full anatomy of a structure without disintegrating it. Engineers should become fully conversant with these instruments and avail of them whenever in doubt (see table). Non-destructive testing instruments are accurate, easy to operate and give quick results. All new structures should be thus evaluated before being put into use and all outlived structures should also be tested before their demolition. This practice can minimise visual assessment and guesswork. Marble Flooring Natural sunlight and warmth flowing freely across shining floors; colours with a futuristic look, classy showcases and a sophisticated but functional living space…this is the dream scenario of every home owner or builder. This can be converted into reality provided economical alternatives are adopted that provide equally good service and cut down construction costs. Flooring, for example, eats up a major percentage of the total cost of a building. The latest trend is to provide marble flooring in buildings. A fine and traditional alternative to marble flooring is pure white terrazzo flooring in white cement with 4-7 mm. white marble chips, rubbed and finished with granite polish. The strips to be provided in the floor would also be white, of plastic. This flooring looks wonderful and is much cheaper than marble; the only consideration is to engage good masons and use good quality white cement and marble chips. While laying absolutely white terrazzo flooring, care has to be taken that the cement, chips and strips have to be pure white with no pigment or coloured chips. Full attention has to be paid to the rubbing and polishing of the floor. White cement and chips are to be mixed as one part cement with one-and-a-half part chips and laid in a 9 mm. thick layer. Sometimes, the mason insists on a one-to-one ratio of cement and chips; this is not to be allowed! Neglect of Safety Safety is often given short shrift by builders and engineers. Irreparable loss of money, manpower and progress may occur whenever scaffolding fails, a roof collapses or a fatal accident takes place at a site. With the loss of a worker's life in an on-site accident, the morale of the working force usually sinks and affects work progress. The Indian construction industry is highly labour-intensive. Although mechanisation in construction projects is inevitable, cheap and unorganised labour is convenient and profitable to builders. It is thus time for a 'Construction Safety Manual', to be made a part of the standard tender document in every organisation and strictly enforced by the supervising agency. Such a manual should include guidelines on safety measures to be taken while handling tools, equipment and machinery; safety arrangements to be made at the work site; safety measures to be taken when work is in progress; accessories to be provided to workers; and the organisational set-up of the safety organisation to be established at the work site. Non-Usage of Admixtures and Compounds The construction chemical industry has developed very fast, aiming at a synthesis of chemistry and construction. The world over, there has been something akin to a revolution in the development of admixtures and compounds. The development of concrete admixtures, like plasticisers, super plasticisers, accelerators, retarders and air entrainers; waterproofing admixtures; protective coatings, which are epoxy, silicon, rubber, polyurethane, liquid chemical and modified bitumen based; adhesives like epoxy adhesives, styrene butadiene rubber adhesives, polymer-based non-saponification adhesives and cement-based powder adhesives; and sealants have all opened up endless possibilities of easier laying of concrete, saving old buildings, making new buildings damp-proof, impervious and efflorescence-free, and increasing the life of materials prone to corrosion. These admixtures and compounds can enhance the quality of construction, provide complete waterproofing, protect floors against abrasion and chemical action by the application of protective coatings, create water-repelling barriers and seal all types of cracks in sanitary ware, plumbing joints, stoneware, walls and roofing. However, the use of these admixtures has not yet become common in India. There is no real reason for not taking full benefit of these materials. In sum, the Indian construction industry has shown great reluctance in adopting new techniques and materials for construction; thus depriving itself of the many benefits they promise. Finding it more convenient and expedient to continue following old practices, it has still not overwhelmingly adopted RMC, non-destructive concrete testing, flyash bricks, and admixtures and compounds. The four basics - safety, quality, economy and speed - have to be urgently taken note of in order to avail of the tremendous opportunities promised by the 21st century.
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