 Welcome you all. Myself, Mr. SK Kulkarni, Assistant Professor, Balchan Institute of Technology, Sholapur. I am here to discuss with you workability of concrete, mainly slump test. Learning outcomes of today's session are, at the end of this session, students will be able to describe workability of concrete and codal specifications and they will be able to perform slump test on concrete in laboratory. What is workability? Workability of concrete is the ease with which concrete can be mixed, can be placed, consolidated and finished. So, when will be concrete called workable, when its internal friction between the particles of concrete will be minimum and lubrication will be good. Then only it can be easily mixed. Such a concrete is called a workable concrete and strength of concrete decreases with increase in workability beyond certain limit, remember. Here we can see workable concrete flowing easily. Now, there are some factors which affect workability of concrete, which are those first is water content, then mixed proportion, size and shape of aggregates, more the size of aggregate, less will be the surface area and more will be the workability of concrete. Surface texture of aggregate, rough the surface texture of aggregate, then more will be the surface area, less will be the workability likewise. Combining of aggregates and use of admixtures like super plasticizers, etc., all these factors affect workability significantly. Now, how to measure this workability? IS code has or Indian standard codes have devised these tests for measuring workability of concrete. Slump test, compacting factor test, flow test, wavy consistometer test mainly today we will focus on the first test that is slump test. Generally slump and compacting factor tests are used widely for measurement of workability and the degree of workability depends on the values of test results given by these workability tests. Now, there are certain specifications which are laid down for this slump value of concrete by Indian standard code IS 456, 2000. Degree of workability is divided into three parts for three ranges we can say low, medium and high, which will be lower workability of concrete when slump value which is measured in mm that we will discuss here after 25 to 50 mm of slump in mm shows that concrete is having lower workability and where this concrete is used for works of roads where the hand operated machines are used for vibrating the concrete and also mass concrete foundations. Then medium degree of workability when slump value ranges between 50 to 100 mm it comes under medium workability range and this work this particular concrete is used normally for all important types of works right. Then high workable concrete when it will be called high workable when slump is between 100 to 150 mm and it is used when sections with congested reinforcements are there. Slump test apartheid is devised by IS 7320 1974 which shall be used for performing this test here you can see the photograph and here the dimensions of the mold so standard dimensions are given this particular mold only shall be used for this test along with tamping rod with scale and travels. Now let us see step by step the test procedure which is given by IS 1199 1959 which are the steps. Step number one the internal surface of the mold is first cleaned and then thin layer of oil is applied to the internal surface. Then mold is placed on smooth horizontal rigid and nonabsorbent surface this is the next step why the internal surface is oiled so that there should not be any concrete which will be sticking to the internal surface of the mold after the test is done right. Then mold is filled with concrete in four layers remember mold is filled in four layers every one fourth height of the mold is tamped with the help of tamping rod 25 times remember right and the tamping should be done evenly over the cross section after top layer is rotted the concrete is truck of level with travel and now the mold is removed from the concrete immediately by raising it slowly and carefully in vertical direction here you can see. Now the concrete will slump or it will subside now what is the level difference between the height of the mold and subsided surface of the concrete that is matured and it is reported as slump of that particular concrete in mm. Now there are generally three to four patterns of slump of concrete depending upon the type of slump first is true slump when the slump is or the subsidence of the concrete is even right evenly it slumps it is called as true slump this first case is of true slump it is desirable one but generally sometimes it may shear the slump and it may be collapse slump or it may be zero slump what is shear slump if one half of the concrete surface slides down then it is shear slump when it will be shear slump when concrete is non-cohesive and it shows segregation of concrete. So how to measure the slump take the average of two levels and find out the slump then third is collapse concrete suddenly collapses like in third case when workability is much more you will see that collapse is there and one more type is zero slump there is no change of levels when workability is zero there will be zero slump significance of this test remember when the concrete mix is a plastic one it will give good slump value or consistent value if it is not a plastic mix or it is a stiff mix we will find that the variation is much less or almost zero so in such cases or when concrete is stiff we cannot use the slump test for measurement of workability is 456 suggests for such a low category of workability we should go for compacting factor test another test for measurement of slump now here is one exercise for you dear friends we will stop while here this particular example you have to solve say in a certain slump test height of subsidence of concrete after removal of mold is observed to be 200 mm if the height of mold is 284 mm initially compute slump of the concrete comment on workability of workability range of this concrete in which this slump value lies here are the answers slump of concrete height of mold minus height of subsidence of concrete so you will find that 285 minus 200 slump is 85 mm remarks as the range of slump is between 75 to 100 mm this particular concrete comes under medium workable range and so workability is medium one here are the few references go through this thank you.