 I am here to talk with you on consistency and compressive strength tests on cement and ice specifications. Learning outcomes of today's session are at the end of the session students will be able to describe codal specifications for consistency and compressive strength on cement, perform standard consistency and compressive strength test on cement in laboratory. There are many ingredients like cement, sand, coarse aggregate, water and admixture if any which are added together to manufacture good quality concrete. It is important to know the properties of these ingredients as they impart strength and durability to concrete. We know cement is the most important constituent of concrete because it is used to bind sand and aggregate in presence with water and it registers atmospheric action. There are specifications laid down by different ice cores for different grades of cement. Like for 33 grades of cement, ice 269, 1989 gives standard specifications and likewise. Now, standard consistency, this particular test its permissible values or their normal range generally lies between 25 to 36 percent. The compressive strength after curing of 3 days for 33 grade cement should be minimum 16 Newton per mm square, after 7 days of curing should be 22 Newton per mm square and after 28 days it should be 33 Newton per mm square. These are the minimum values for 43 grade these values are 23, 33 and 43 for 53 grade these are 27, 37 and 53 Newton per mm square respectively. Now let us study standard consistency test of cement. This particular test is carried out as per IS 4031 part 4, 1988. Now what is normal consistency or consistency? It is a minimum percentage of water by weight of cement which is required to be added in cement for its hydration and which will form a consistent paste. Now what is standard consistency? There is a little difference. The standard consistency of a cement paste is defined as that consistency which will permit the wickad plunger to penetrate to a point 5 to 7 mm from the bottom of the wickad mold. And what are the normal values of standard consistency of cement? The range between 25 to 36 percent. Now let us see consistency test procedure objective to obtain standard consistency of cement. Apertise used wickad's apertise here you can see wickad's apertise with plunger. And this particular test should be carried out at a temperature 27 plus or minus 2 degree centigrade and the relative humidity of the laboratory should be 65 plus or minus 5 percentage. Now firstly what is done in this particular test? Cement of 400 grams is weighed accurately on a weighing balance and water which should be potable water or distilled water is taken and initially 30 percent of water can be taken as a trial percentage because this is a trial and error procedure. If 30 percent water does not give the results you have to change the percentage of water. So initially you can start from 30 percent and remember mixing time should not be less than 3 minutes and not more than 5 minutes. The mixing time will be counted from time of adding of water to the dry cement till the commencement of filling the mold of wickad's apertise. Now here you can see the wickad's apertise. This mold is completely filled with this particular pest. It is labeled then it is shaken so as to expel the air if any and now the plunger is brought in contact with the pest and it is released from there. Now plunger is having diameter 10 mm and 50 mm is its length. Now when this is released it will penetrate into the pest. Now this penetration from bottom should be 5 to 7 mm here we can see from bottom it should be 5 to 7 mm. If this condition is satisfied that particular percentage of water is taken as standard consistency of cement. Otherwise percentage of water is changed mix is changed and this particular test is again repeated till we satisfy this particular condition and that particular percentage is taken as percentage consistency for that particular cement. Now let us see compressive strength test of cement which is performed as per IS-4031 part 6, 1988. Now compressive strength of cement is determined by taking compressive strength test on mortar cube which is compacted by means of a standard vibration machine and the standard sand as per IS-659-66 is used for preparing these mortar cubes and size of the mortar cube is 70.60 mm. Now objective to find compressive strength of cement materials used standard sand, water, cement sample, apartus, cube molds, straw well, mixing tray, vibrating machine, timer, weighing balance etc. Now let us see the procedure. Take 200 gram of cement and 600 gram of standard sand and mix them dry thoroughly. Now add water P by 4 plus 3 percent of total weight of cement and sand. In this P is percentage consistency, percentage of water which is obtained in consistency test and total weight of cement and sand is 800. So that much water is added. Now these cubes, these are the cubes of size 70.6 mm, these are initially cleaned and internal faces of these cubes are oiled so that any cement will not stick to the interior surface and these cubes are filled with the mortar and these cubes are vibrated on this vibrating machine for two minutes specified speed of vibration is 12000 plus or minus 400 per minute which will achieve full compaction. Now these cube molds are removed from the machine and they are kept at 27.2 27 plus or minus 2 degree centigrade and relative humidity of 90 percent for 24 hours. Now after 24 hours these cubes are removed from the mold and immersed in water as they are shown here for curing. At least nine cubes are prepared in this manner and now these cubes, three cubes are tested for three days, three for seven days and three for 28 days according to Indian Standard Code on compression testing machine as shown here. Weight of loading should be uniform and it should be 35 Newton per mm square per minute. This is the specified speed as per ISCO. Now here is one numerical problem for you. Let us solve this. What is it? In a 28 days compressor strength test on cement one specimen is observed to be having strength of 43.5 Newton per mm square. What is the actual load carried by the specimen in kilometer? What is the grade of cement? You have to comment on grade of cement. Now let us solve this problem. Now we know dimensions of cubes which are cast in this particular test are 70.60 mm by 70.60 mm by 70.60 mm. Hence cross sectional area on which load is acting will be 5000 mm square. So now using the relation stress or strength of the concrete specimen, this mortar specimen will be equal to load divided by cross sectional area. Now strength is given as 43.5 Newton per mm square, keep the values is equal to P, let P be the load which is unknown divided by cross sectional area is 5000 P is equal to this much Newton. Find out the value in kilo Newton dividing it by 1000. So it is 217.5 kilo Newton. This is the answer. Now in remarks what you will comment? This is a 43 grade cement because it is 28 days strength is more than 43 Newton per mm square. Now friends here is one exercise for you. Let us pause video for some while here and solve this problem. Cement mortar cubes are being tested in machine, average load carried by specimen is 270 kilo Newton. What is the average compressive strength of this particular cement? And what is the grade of this cement? And second question, this is generally consistency of cement ranges from the blank space is there to this particular percentage. Now solve these two problems, here are the answers. Compressive strength of cement comes to be 54 Newton per mm square. And grade of cement is 53 because the strength is more than 53 Newton per mm square. And consistency of cement ranges from 25 to 36 percent. These are the answers. Now these are the IS codes which are there for methods of tests on cement. These are generally referred for methods of tests on cement. And these are the IS codes for specifications on cement. So IS 269 is there and these codes are there. Now these are the references, go through these references. Thank you.