 Mr. Chetanji Kunapuri, Assistant Professor, Department of Cellular Engineering, Walsh and Institute of Technology, Solapur. These are the learning outcomes. At the end of this session, students will be able to explain the ready-mix concrete abbreviated as RMC and the provisions of ready-mix concrete. Now, let's see the introduction. RMC is the specialized material in which cement, aggregate and other ingredients are way-badged at the plant in a central or truck mixer before delivery to the construction site in a condition ready for placing by the customer. And by simple understanding, we can say that RMC is manufactured at a place which is away from the site. It may be RMC plant and the construction site. These are the two locations. These two locations are linked by transport operation. Now, as per our IS, IS 4926-2003, concrete mixed in a stationary mixer offers central batching and mixing plant or in a truck mixer and supplied in a fresh condition to the purchaser either at site or into the purchaser's vehicle. So, this is the definition given by our IS. Now, why RMC, why ready-mix concrete shall be used? Several advantages are given and their explanations are also given. Let us see one by one. First is uniform and assured quality. Concrete variation is possible because of the batches. At every batch, there may be variation in the concrete and that variation will give some quality issue, quality problems in our concreting. So, for uniform and assured quality, so factory or plant, that is important. Factory made or plant made or factory manufactured some concrete. That is called as RMC concrete. So, the raw material and the production process quality will be better and uniform for the concrete which is made at plant. So, that is why we can select the RMC concrete. Second is durability of the concrete. How it is related to durability? That is because of this parameter. That is the correct water cement ratio. Correct water cement ratio can be maintained in the RMC concrete. So, durability of the RMC is consistent and better because on site, the water cement ratio and its control is difficult as well as very regular issue on site. Next is faster construction speed. In site-mix concrete, the contractor needs to mobilize the labor for mixing as well as for placing. So, in RMC, concrete supplied in a placeable condition can be directly placed by pumping. Hence, faster construction can be assured. Now, for a small works, so mobilizing the labor and placing of the concrete, whatever team is required, that is possible for big works. If a ready-made concrete is available, which can be directly placed, that will assure your faster construction. Next, elimination of the storage needs. Now, in very metro cities or the cities where the traffic is the problem, traffic is the issue. So, the stacking of raw materials is a big issue nearby the site. So, in urban situation, there is a problem of storage of raw materials. So, this will actually have given rise to the RMC concrete that is used for different purposes. Next is easier admixture addition. This is one more problem after the water cement ratio control, that is how to add the admixture and its proper dosage. So, in RMC, the admixtures can be added into controlled manner because of the use of sophisticated computer-controlled methods. And this is not possible in normal concrete. Now, reduction of the wastage of the material. This is an added advantage or we can see saving also. So, RMC materials are stored in bulk and used in bulk. Our wastage that occurs in loose handling of cement is completely avoided. So, let's see what RMC plant consists of. A, RMC plant with some auxiliary or supporting equipment. B, transit mixers. C, site equipment for handling. Now, for a small town, the capacity of the RMC plant, that is 55 to 60 meter cube per hour, would meet the requirements. Now, the working of that RMC plant we can consider 8 to 10 hours per shift. These are the auxiliary equipment which are required for the RMC plants. So, folk lift truck, wave bridge, captive diesel sails, storage cement silos for 2-3 days capacity, front end loader, telecommunication system, admission tanks, site laboratory. Now, let us see the typical layout and lab equipment required for RMC site. And it is shown in this figure 1 and the equipment which are required at the site laboratory, these are also shown in this table 1. You can see this site layout, these are required on site. Now, one more diagram is shown here which will show you the schematic of ready mix plant. You can see here different components are shown here. This is aggregate stacking, the cement silos, then pan mixer, then through the wave etcher the aggregates are stored or mixed in the pan mixer. And finally, the concrete is poured in this truck and through the truck it is transported to the site. So, these two batching plants are shown here for your reference. These two batching plants are shown and this is RMC unit. Now, let us see about the concrete specification. Is there any separate specification for ready mix concrete? Concrete RMC concrete is merely concrete manufacture away from the site with the exception of requirement for delivery. There should be no difference between specification of concrete and specification RMC because for RMC concrete is the specification difference and for site mix concrete specification that is not there. Only the basic aim is that specification of structural concrete is to control water cement ratio at different levels. This is the only issue and it is to produce concrete for of different qualities. Now, mix proportion specification, this is one of the specification through which water cement ratio is controlled through the mix proportion and the workability of the fresh concrete can be assured. Now, following table shows the concrete mix information to be furnished by the purchaser to the RMC supplier. So, all of you can see these particulars. What information must be given by the purchaser during every mix and load? So, you can see most important grade, chemical additives, mineral additives, then water cement ratio, maximum aggregate size, target workability and whatever workability is actually retained on site that you can check. This is important. Then, the most important thing is concrete testing frequency and any alternatives offered. These things you can see on this information. According to this information, you can assess the concrete on your site. Now, these are the codal provisions. Now, for making ready mix concrete, we have IS 4926-2003 and one more code is there that is American Standard Testing of Materials Code that C94. Now, most important parameter in that the time that elapsed says from the instant of adding of water to the placement of concrete. This is most important parameter in both the codes. Now, let's see about our IS Indian Standard 4926-2030 general requirements and clause 5 starts with the basis of supply. It must comply with the requirements of IS 456. RMC concrete must comply with RMC 456. Basic thing is IS 456 for that. All concrete will be supplied in terms of cubic meters and all proportioning is to be carried out by mass except water and admixture. So, this is the main thing. Ingredients must be proportioned with the mass and concrete must be supplied in terms of volume that is cubic meter. Water and admixtures can be used with the volume base. Now, time in transport, concrete shall be discharged from the truck mixer within two hours of the time of loading. This is suggested by our IS. For longer periods, it may be permitted if suitable retarding admixtures are used in cool or humid weather or chilled concrete is produced in that case only. In case of this time, IS TMC 94 permits only 90 minutes or before the drum has made 300 revolutions, whichever is earlier. Next is sampling and testing of RMC clause 6. For assessment of ready mix concrete, the point and time of sampling shall be at the discharge from the producer's delivery vehicle or from the mixer to the site. Now, this is the workability requirement you can see for slump and compaction factors, these things are given 25 mm plus or minus tolerance or 1 third plus or minus from the specified value. If the value is specified, some value specified, this tolerance can be considered. Let's even question based on this tolerance. If the specified value of this slump is 100 mm, what are the limits of the acceptance for workability due to delay of delivery? A is 75 to 125 BCD. Now we pause the video and give the answer for this. It is A 75 to 125 mm. Now, regarding this specified strength, the requirements of IS 456 must be satisfied by ready mix concrete. Sampling can be done after every 50 cubic meter or every 50 batches, whichever has a large frequency. Three specimens shall be made for each sample for testing at 28 days. And for quicker idea only, you can take models of rupture tests, bending tests of the concrete, by taking the beams after three days. After seven days, you can test compressive strength test. You can test 28 days compression test, but in all cases, 28 days compressive strength shall alone be the criteria for acceptance or rejection of the concrete. Other things are for your idea of quality that this test, but only 28 days is the criteria for acceptance or rejection. These are the references for the above session. Thank you.