INFOCUS The graded aggregate and sand is dropped into the weighing machine, lifted to the mixer where the cement, admixture and water is added, mixed, and then dropped into the transit mixer. The pump lifts and pours the concrete to the construction level/area. 81. What is Ready Mix Concrete? Ready Mix Concrete (RMC) has cement, aggregates, water and other ingredients, which are weigh-batched at a centrally located plant. The concrete is then delivered to the construction site in transit mixers which are trucks fitted with rotating drums for carrying concrete. This concrete is in plastic condition which requires no further treatment before being placed in position to set and harden. At the construction site, it is placed by pumping with concrete pumps which can pump up to 100m horizontally and 20m vertically at the rate of 30cum/hr. 2. What are the advantages of RMC? • Better quality concrete is produced under a controlled environment. • Elimination of storage space for basic materials on site. • Elimination of procurement / hiring of plant and machinery on site. • Wastage of basic materials is avoided. • Labour associated with production of concrete is eliminated. • Noise and dust pollution at site is reduced. 3. What are the limitations of RMC? • The materials are batched at a central plant, and the mixing begins at that plant, so the travelling time from the plant to the site is critical over longer distances. • Transportation on roads with heavy traffic and narrow widths has been one of the major limitations for RMC to be used in Kathmandu. To overcome this limitation, most of the times RMC is delivered during night time when the traffic is not a hindrance. But this requires additional management of resources and labours on site to lay the concrete during night shifts. www.spacesnepal.com 30 • Concrete's limited time span between mixing and placing means that readymix should be placed within 90 minutes of batching at the plant. Sometimes, due to lack of management, the site staff is not well-prepared to lay the concrete immediately after the RMC pumping setup is ready, which causes damage to the concrete mix due to delay. Similarly, if the manufacturers delay the process of connecting the pumping equipments and pipes on site, the concrete mix is damaged due to delay. Thus, site staff as well as the manufacturers should be pre-informed and well-managed to take the best advantage of RMC. 4. What are its benefits over sitemix concrete? Parameter Site Mix Ready Mix Quality Varying Consistent Wastage on site 4-16% Nil Labour Required 20-30% 5-7% Time Required for Concreting (for approx. 1500Sqft) Storage of raw materials <strong>Nov</strong>ember-<strong>Dec</strong>ember <strong>2010</strong> 6-8hours Space Required in site 2-3hours No space required on site 5. How is the quality ensured? Different tests for fine aggregates, coarse aggregates, water, fresh concrete, hard concrete and for admixtures are carried out for the preparation of the concrete in a well equipped laboratory. Trial mixes are carried out and tested to ensure that each and every batch of concrete coming out of the plant meets the parameters of the client's requirements. <strong>6.</strong> What is the minimum quantity that can be purchased? Normally, the minimum capacity of a transit-mixer is 5cum. Thus, any construction of using more than 5cum can use RMC on site. However, using it on sites which has bulk requirement of concrete increases the efficiency and reduces the cost of RMC. 7. Is RMC expensive? Comparing with a good quality site mix concrete, it is observed that RMC costs about 10-15% more. But at the same time, the saving of time and assurance of quality is higher than the site-mix concreting. Thus, the cost of RMC needs to be weighed considering the site situation and the quantity of concreting required. Panchkanya Group Always Ahead, Always First Panchkanya Group of Industries is the first in the country to establish Ready Mix Concrete plant in Kathmandu. Known for innovative products and state-ofthe-art technologies, the Panchkanya Group which began in 1971, is a leading industrial and trading establishment of Nepal. Dealing with various products like Steel, Ready Mix Concrete, Bitumen, Plastic, Pipes, Wires & nails, etc, the Group has created its own brand name in the country. For more information : www.panchakanya.org
<strong>Nov</strong>ember-<strong>Dec</strong>ember <strong>2010</strong> 31 www.spacesnepal.com
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