 Welcome to the session self-compacting concrete, abbreviated as SCC, myself Mr. Chetanji Konapuri assistant professor, Department of Civil Engineering, Volchian Institute of Technology. Now, the learning outcomes for the sessions are, student will be able to understand the concept of self-compacting concrete, now what are the materials required for self-compacting concrete. Now, workability property is required for self-compacting concrete. Though self-compacting concrete the term itself is little complex, basically the concrete structures are made with vibration, means during concreting casting vibrations are given for achieving the full compaction. External efforts are taken to give full compaction to the concrete. But without compaction if the concrete is to be concreting is to be done, then what additional measures we have to take or what additional thing we have to do if the concrete without vibration or concrete casting is required to be done. So, that concept is in their self-compacting concrete. Now, there are some examples in which vibrations are not used full compaction is not actual, means underwater concreting is there, mass concrete is there, where vibrations are not given without vibration this concrete is done. But in these examples the strength is very less and consistent quality is not obtained in those types of concrete in which vibrations are not given. If consistent quality is required, if full compaction is to be achieved then external vibrator, external efforts are required or we have to apply vibrations to the concrete to get the full compaction. Now, self-compacting concrete is focused on high performance, better reliable and uniform quality. One is the consistent quality and concreting without vibration that is the basic concept of self-compacting concrete. Now, the recognition they have recognized means recognizing the lack of uniformity and complete compaction of concrete by vibrations. If this is to be achieved the researchers at University of Tokyo started to develop the concrete that concrete is known as self-compacting concrete. So, early 1990, Japan has developed and used the self-compacting concrete which does not require vibration to achieve full compaction. So, that was developed in Japan. Now, what are the materials required for self-compacting concrete? Same ingredients are used or anything else anything addition is done in that. Let us see. Regularly our cement OPC ordinary Portland cement 43 or 53 grade material is used. Aggregate theoretically 20 mm maximum size aggregate is allowed in self-compacting concrete. But 12 to 10 mm aggregates are required practically. Now, regarding mixing of the water, the same thing as we have the quality of the water which is assured for our regular concrete. The same thing can be considered for this self-compacting concrete. Next thing is chemical admixtures means admixtures or additions in the concrete is the having major part in self-compacting concrete. Basically super plasticizers are used in self-compacting concrete and we which is even an essential part of the self-compacting concrete. But the base of self-compacting sorry super plasticizer must be polycarbolic silated ethers. PC based super plasticizers are required. Next thing is there for stability purpose viscosity modifying agents are used for improving the free and freezing thaw resistance. Air entering agents are used and for controlling setting retarders are used. So, chemical admixtures is playing very important part in this self-compacting concrete. Next is mineral admixtures. So, self-compacting concrete means it must flow with its own weight so that there must be higher powder content. So, mineral admixtures are used for that. So, flash is used to improve the durability. Ground granulated blast furnace slag that is used to improve the rheological properties of the concrete. Silica fume one more fine powder used to improve the mechanical properties like strength parameters, compressive strength, legional strength, stone powder or finely crushed limestone or any other powder content. But the powders particle must be of smaller than or lesser than 125 micron can be used in the self-compacting concrete. Now, how the self-compacting concrete can be made? What are the methods or ways to make the self-compacting concrete? One thing is there first is you can increase the powder content of self-compacting concrete. Powder means cementitious material you can use in that. Second is you can improve the viscosity of that concrete means by addition of viscosity modifying admixtures means we will get proper flow. Both we can combine powder type we can increase the powder as well as we can improve the viscosity also the third way is to combine both the methods. Now, what are the requirements of self-compacting concrete? Why how we can call that concrete as a self-compacting concrete and to make the self-compacting concrete what are the requirements? One is there whenever we go for the design of or proportioning of that mix first thing is that the concrete must be able to flow under its own weight without vibration. So, we should make that type of concrete for which vibration is not required it must flow under its own weight. Now, whatever may be the reinforcement it may be dispersed reinforcement may be closed reinforcement may be very congested reinforcement the concrete should have the property of flow and it must flow under its own weight for all type of reinforcements. Next thing during this flow it must maintain its homogeneity there should not be any segregation also. So, maintaining the homogeneity with congested reinforcement without vibration under its own weight it must occupy the volume of casting the best natural example for self-compacting concrete is honey. Honey is the material if we pour honey in any shape and size of mold or container it will occupy the entire volume with the shape of that container or mold. So, we should make the concrete of honey nature. Now, concrete mix can only be classified as self-compacting concrete if it has following characteristics. First is filling ability second passing ability third is segregation resistance. Now, several tests are there several test methods are developed to characterize the properties of the concrete. Property is first is filling ability second passing ability third segregation to resistance. Now, the test methods are for the laboratory are designated for field control quality control the tests are designated some modifications are also suggested in the based on the maximum size of aggregate. Now, these are the test slump flow v funnel l box u box and all these tests are there to characterize the properties of concrete. Now, these are the workability requirements for the fresh self-compacting concrete. Now, first is slump flow by Brahms cone minimum it must be 650 mm maximum 800 mm. Now, next again slump flow is there but it is measured based on the time minimum 2 second maximum 5 second j ring test it is measured in mm maximum it should be of 10 mm v funnel test it is measured in time minimum 8 second maximum 12 second. Now, what are the complexities involved in making self-compacting concrete? So, we should think of those complexities and then we can proceed to the proportioning or mixing of self-compacting concrete. Concrete actually it is a heterogeneous material but we should make that as a homogeneous material. So, normal strength concrete itself is a complex material high strength and high performance concrete making of the high strength and HPC HSC HPC requires a very lower water cement ratio or water binder ratio that is again one complexity. Making of self-compacting concrete with high strength so which adds further complexity. The next thing is the basic characteristic of self-compacting concrete is flow and whenever the concrete which requires higher flow and higher strength both these two parameters are connected to each other. High strength require low water binder ratio high flow requires high workability high flow. So, for high strength silica fume is used which reduces the workability to unacceptable level and to restore this workability high dosage of super plasticizer is needed. But there are two problems of high dosage of super plasticizer two problems first is high dose all super plasticizers are not suitable for high dose and the side effects are excessive retardation this is the second problem FNR specification recommends paste volume to be more than 40 percent of the volume. So, again it requires higher powder content so which requires new generation plasticizer to disperse the concrete. So, one thing is there super plasticizer with the base of poly carboxylate shall be used which add cost into the self-compacting concrete. So, these are the references for the self-compacting concrete sessions. Thank you.