 Welcome to the session High Performance Concrete. This is Professor C.G. Konapure, Department of Civil Engineering, Vulture Institute of Technology, Sulapur. Now at the end of this session, students will be able to understand the concept of high performance concrete, aggregates used for high performance concrete, mixtures of high performance concrete means some of the proportions. These are the learning outcomes for high performance concrete. Now let us see what is the high performance concrete, the concept. High workability, high strength, high density, low permeability and resistance to chemical attack. This is the first concept involved in high performance concrete. High performance concrete is also high strength concrete but it has few more qualities. Even by densification and strengthening of transition zone, many desirable properties can be improved. Now the fourth one is reducing the quantity of water is the fundamental step for making HPC. Now HPC, high performance concrete I will designate as HPC. Next thing is use of mineral and mixture is necessary in case of high performance concrete. So why it is required? It is required to improve the quality of transition zone. For that purpose use of silica fume which is one more mineral and mixture, it is to be used and it is necessary. Transition zone means the zone between aggregate and cement paint which is nothing but the pond also. Now the second mineral and mixture best quality of fly ash. That mineral admixture also we can use. Third one more mineral admixture is this GGPS. GGPS is ground granulated blast furnace lag. So silica fume, fly ash, ground granulated blast furnace lag, these three mineral admixtures are generally used in high performance concrete. Now all these materials when cement is used, mineral admixtures are used and if these three mineral admixtures which were explained earlier statement. If all these are combinedly used then the water demand will increase. So all these materials required increased water demand. In that case we need to use this chemical admixture. Use of chemical admixture is now compulsory in case of HPC. So chemical admixture specifically use of appropriate super plasticizer is a key material in making high performance concrete. So super plasticizer actually which disperse all the ingredient particles in the concrete. So which will disperse and based on that dispersion the workability of high performance concrete can be increased. Second thing compatibility and optimum dosage of super plasticizer shall be designed. Now whatever super plasticizer is used whether it is compatible for that concrete or not then once it is compatible then optimum dosage of that super plasticizer which required to increase the workability of that concrete that optimum dosage shall be designed. Now next thing is aggregates for high performance concrete. In normal strength concrete the strength of aggregate by itself play a minor role. In case of normal strength concrete aggregates are important but the strength of aggregate plays a minor role. When it comes to HPC where the bond between aggregate and cement paste is so strong that results in significant transfer of stress across transition zone. So this bond between aggregate and cement is very important and it must be strong means the entire load or stresses that must be transferred through transition zone to the aggregates. Strength of cement paste is higher than the strength of aggregate because of low water cement ratio. In case of normal concrete the strength of aggregates is more than the matrix or mix of their cement paste but in case of high performance concrete strength of cement paste is higher than the strength of aggregate. This is because of only low water cement ratio. When water cement ratio is reduced this paste becomes very hard. Now the key question in this presentation is what is the aggregate size used for high performance concrete. So just you pause the video and answer about this what is the aggregate size for HPC. So here the explanation is given. Practical experience up to 100 MPa maximum size of aggregate we can keep 20 mm up to 100 MPa. If your concrete is having strength more than 100 MPa then 10 to 12 mm aggregates can be used. Shape crushed aggregates can be used cubic crushed aggregates. Now many instances the strength of aggregate particles has been found to be factor that limits the comprehensive strength of the high performance concrete that is why the aggregate size is important. Now the last important point which is disadvantageous for HPC there is a more flaky or elongated materials decreases the workability and also the strength. So flaky aggregates elongated at aggregates these are generally in case of normal strength concrete also reducing workability strength. But in HPC that reduction in the workability and strength due to this flaky and elongated material is very large. Now these are some typical mixtures, typical HPC mixtures used in some important buildings in USA and other countries. So this reference is from a MSHET book. So we will discuss only these first and second mix. Now we can see water which is used to produce one meter cube of concrete water requirement is 165 kg per meter cube. Cement used 505 kg per meter cube. Flash 60 kg per meter cube. Coarse aggregate 1030 kg per meter cube. Fine aggregate 630 kg per meter cube. Now this water reducer we can see here is 975 ml per cubic meter means 0.975 liters per cubic meter that much water reducer is used. If you see the water cement ratio water is 195 cement is 505 water cement ratio is never about 0.35. Now this picture has given strength at 28 day 65 and again it was checked at 91th day. So strength gain is again observed and that strength is improved up to 79 MPa. Second mix you can observe here these are the weights of these materials given. Just the thing is the difference in first and second is water cement ratio is little increased that is 0.37. Super plasticizer that is used retarder is also used. So the difference in first and second mix is use of chemical add mixtures. Now the strength at 28 day for the second mix is 80 MPa and at 91 day it is 87 MPa. So here you can see these five buildings which are constructed by HPC water tower place Chicago, Joigny, Bridge, France and some other structures. These are the references which are used for this session. Thank you.