 Welcome to the session, High Performance Concrete, myself, Mr. Chetan G. Konapure, Assistant Professor of Department of Cellular Engineering, Virgin Institute of Technology. Now these are the learning outcomes at the end of this session, student will be able to understand the silent features of high performance concrete, mixtures of high performance concrete. Now the regular concrete or conventional concrete, we know that it is a mixture of ingredients and in earlier session we have seen high strength concrete, the one parameter was there that is the strength which was enhanced in a high strength concrete. Now the term high performance concrete means the performance means what? What are the performance criteria? So high performance concrete is used to refer the concrete for a required performance for measurement of the construction application means basically based on the industrial requirement and the construction applications the performance level for different parameters and properties can be enhanced and that concrete is called as high performance concrete. Now high performance concrete is also high strength concrete but it has few more qualities. Now what are the performance criteria? What are the these qualities which can be enhanced? For example, high workability, high strength means workability and strength can be enhanced that is a regular thing in the concrete but what are the other performance levels? Next thing is high density, low permeability, resistance to chemical attack, resistance to sulphate attack all these things actually reveals more durable concrete or high durable concrete. So durability of the concrete with high strength and with other enhanced properties is basically high performance concrete. How that can be achieved? What is the theme in that achieving of high performance concrete? So densification and strengthening of the transition zone that will give us some enhanced their desirable properties and that these properties can be improved by this theme of densification and strengthening of transition zone. Now what is transition zone? Transition zone is the coating on the aggregate may be fine aggregate or coarse aggregate coating of the cement paste surrounding to these aggregates. So the stresses are transferred from matrix cement paste to the aggregates that zone is called as the transition zone. Now let us see the schematic diagram which explains the approaches for production of HPC. How the high performance concrete can be produced? Basic theme is all parameters like workability, strength density are with high requirements but most important thing is durability. High durability is also expected especially durability is the key parameter in the HPC. Now there is one approach that is reducing the capillary pores we can achieve. Second way is we can bind the sites to prevent the transportation of chloride ions. So these two approaches are useful for production of HPC. Now these capillary pores are the sources through which the durability of the concrete may affect. And second thing is the chloride ions that will also affect the durability of the concrete. So both the things can be controlled in HPC to get the high performance concrete, high durability concrete. How these capillary pores can be reduced? Next is we can go for reduced water binder ratio for very low water cement ratio for we need admixture. Next is use of fine fillers, silica film we can use, good compaction you improved curing by these four features we can increase the we can reduce the capillary pores. And next is how we can prevent the transportation of chloride ions that is by binding the sites for chloride ions and it is for that we can use cementitious supplementary cementitious material SCM. So supplementary cementitious material are ground granulated blast furnace leg, flash, metacoline, rice husk and blends ash. Now these features are increasing the physical resistance of the concrete means all the mechanical properties can be increased and by using these supplementary cementitious material the concrete can be made durable. So increased physical resistance means mechanical properties may be compressive strength, flexural strength, tensile strength that can be increased and by using supplementary cementitious material durability of concrete can be enhanced. Now the first feature, silent feature use of water now for mixing purpose water is used. Now the fundamental step in HPC is low water cement ratio or reducing the quantity of water in the concrete. So reducing the quantity of water means whatever water is required for hydration process that is actually used and rest of the quantity of water is basically required for workability. So if we go for a lower water cement ratio probably we will get more dense concrete more durable concrete that is the one thing. Now next is use of mineral admixture this is the second thing. Now fine materials the fillers which are having a particle size less than cement those fillers we can add into the concrete. Why these are required as I have explained in the schematic diagram in earlier slide to reduce the capillary pores we have to use the filler material especially silica fume. So the particle size of silica fume is one hundredth size of the particle size of cement. So this can reduce the capillary pores those and most important thing is silica fume improves the quality of transition zone. Now the transition zone is actually the weak portion, weak zone in the concrete. So effective stress transfer is possible through this transition zone. If that is improved your durability concrete will increase. Next is supplementary cement issues material. Now we can use base quality flash ground granulated blast furnace like that can be used. Why it is used? So the chloride ions transportation can be prevented and we can get better durability. Now the chemical admixtures or third silent feature is so use of appropriate super plasticizer this will facilitate to use reduced amount of water which will reduce the water demand and most important thing is chemical admixture is whether that chemical admixture is compatible to the material or ingredient which is used for the concrete may be aggregate, fine and your cement type of cement so compatibility of the chemical admixture shall be checked and the optimum dosage of super plasticizer for the particular water cement ratio quantity of water dosage shall be designed. Now fourth important feature is aggregates for high performance concrete. Now basically the in normal concrete the strength of aggregate plays important role in case of HPC major of the strength of the concrete volume can be taken by this volume of the aggregate. So strength of the aggregate is also important parameter. Next thing is now the load of stresses which is which is coming on the concrete sections in which SPC is used that these stresses from cement paste to aggregate it must transfer and that is by means of only bond between aggregate and cement paste. Now your bond between aggregate and cement must be proper and strong so as your bond between the aggregate and cement paste is good or strong which ensures the significance transfer of stress across transition zone so bond is also important for that your aggregate must be of good quality. Now next thing is as low water cement ratio is used for HPC sometimes strength of cement paste is greater than the strength of the aggregate but what is the aggregate size used for HPC? This is the question for all of you students so just write down the aggregate side for the SPC pause the video. Now for aggregate side for SPC in various authors if the strength of the concrete is up to 100 MPa the maximum size of aggregate is 20 mm and if the strength is more than 100 MPa maximum size may be in between 12 to 10 mm but practically in several trials for the materials which is available for that 12 mm 10 mm is the practically proved aggregate size for HPC. Now the shape of aggregate must be cubic so which gives the proper transition zone and crushed aggregate shall be used. Now in many instances strength of aggregate is important because if aggregates are cut for a particular load so the strength at that cut that failure governs the complication strength of HPC. More flaky aggregate or elongated aggregate decreases the workability and strength. Now these are the typical mixtures for HPC so I have calculated the proportions here the cement and fly ash the both cementations but if you consider one your fine aggregate is 1.82 then sorry coarse aggregate is 1.82 fine aggregate is 1.15 and chemical admixture water reducer is used that is of 1.75 percent. Now we can see here two mixes which were shown in earlier table in first mix I have calculated and shown on that table itself. Now second mix in which water cemetery shows 0.37 and fine aggregate is 1.651 coarse aggregate 2.22. Now we can see here the super plasticizer dose here you can see 11.25 litre per meter cube this dose is 2.6 percent of weight of cement. Now water used in first mix is 125 kg per meter cube water in mix 2 is 165 kg per meter cube. So, in second mix quantity of water is less that is why super plasticizer dosage is more. These are the references for this session. Thank you.