hello viewers and welcome to this series on laboratory measurement in highway engineering aggregates used in the surface layer of the road pavement are subjected to veer due to vehicles moving over it the friction between the moving tire and the road surface results in abrasion of aggregates this effect is further enhanced due to presence of dust particles on road surface therefore the aggregate should be enough resistance against abrasion this property is evaluated by abrasion value test various types of tests can be used for determining abrasion value these are Los Angeles abrasion value test devil abrasion test and Dorrie abrasion test in this program we shall determine loss and less abrasion value of aggregates the apparatus required for this test as per is 386 part four is Los Angeles abrasion machine it has a hollow steel cylinder having an internal diameter of 17 centimeters and length 15 centimeters the machine can rotate about the horizontal axis a removable cover is provided which men clamp is just proved a steel shelf projecting radially is provided for the full length the Shelf is placed at a distance of minimum 125 centimeters from the opening in the direction of rotation in addition we need abrasive charge that comprised of steel balls of diameters 48 millimeters and weighing between 392 for 45 grams 12 such balls should be available for the test their number is dependent on the type of grading used we require a weighing machine preferably an electronic balance of capacity 5 to 10 kg and accuracy one gram or better and i--i sieve of size 1.7 millimeters the other sieve sizes depend on the grading selected the aggregate used for the test comprised of a grading as specified in this table the selection of grading is dependent on its designated use for example for WBM we shall select grading ii for use in SDBC grading b c or d are selected we shall be conducting the test using grading B therefore we shall require is sieves of size 20 millimeters twelve point five millimeters and ten millimeters a total of 2.5 kg of material passing 20 mm sieve and retained on 12.5 mm sieve is taken and also 2.5 kg or material passing 12.5 mm sieve and retained on 10 mm sieve is taken first of all dry the material in an oven maintained at 105 210 degree centigrade for four hours take the material out and allow it to cool to room temperature now measure the exact quantity of the material as per the grading specified and note down the exact weight of sample corresponding to the selected grading take the abrasives charge for grading B we need 11 balls now we shall test this material before starting ensure that the cylinder is clean from inside now place the aggregate sample along with the abrasive charge in the cylinder fix the cover firmly in position check that the counter is reading zero now switch on the machine allow the machine to run at the speed of 32 33 revolutions per minute give 500 revolutions or reading a B C or D and 1000 revolutions for reading e f or g since we are using reading b we will subject the samples with 500 revolution during the movement he aggregate are subject to evasion by this team ball they also rub against each other which is known as attrition the aggregates and the steel balls detained by the shell fall when they reach talk thereby resulting in the impact thus both the abrasion and impact occur during this test therefore this test simulates field conditions better as compared to any other such test after the test is complete open this steel cover remove the crushed material from within this cylinder receive this material through 1.7 millimeter sieve where this fraction passing through sieve to an accuracy of one gram as a counter check also a fraction retained on see determine the loss and list abrasion value as weight of fraction passing 1.7 millimeter sieve as a percentage of total material taken which in this case is found to be twenty five point eight percent repeat the test and report the mean of two samples as loss and this abrasion value Indian Road Congress has specified limits of loss and list abrasion value for different types of road construction the sample tested here has Los Angeles abrasion value of twenty six point six percent which is found to be well within the limits therefore we can conclude that this sample is suitable for construction in SDBC in this program we have seen as how Los Angeles abrasion value is determined due to its measurement of both resistance in abrasion and impact this test remains to be most popular we can conduct other tests on aggregate and found their suitability for use in road construction thank you and goodbye