Determination of Resistance to Fragmentation by the LOS Angeles Test Method - Assignment Example

4. Compare the results of the test with the specifications and diagnose there appropriate use. Apparatus The apparatus that are used for this test are as follow and these all conform to the BSI standard “BSI. (1998-2006)EN 1097-2.. Tests for mechanical and physical properties of aggregates ? Part 2: Methods for the determination of resistance to fragmentation”. 1. Electronic Weighing Balance with a precision of 0.1 g 2. Test sieves used for los Angeles Test are of the aperture sizes of 1.

6 , 10, 11.2/12.5 & 14 mm. 3. Los Angeles Apparatus with all parts and mechanisms. 4. 11 Spherical ball loads/charges with diameter of atleast 45 mm and atleast total weight of 4690g. 5. Miscellaneous apparatus for assistance in movement of material during the test. Procedure 1. The first step would be sampling and preparation of test specimen according to the that mentioned in the standards. BSI. (1998-2006) EN 1097-2dictates that an initial separation is done by sieve of 10mm and sieve no 14mm.

Then from this acquired sample another specimen is produced which contains about 60-70% of passing of 12.5mm sieve and 30-40 % of passing of 11.2 mm sieve. 2. About 5000g of the above sample is prepared and exact weight is measured and recorded along with all details of the aggregate. 3. This sample is then shifted into the Los Angeles Apparatus and then 11 spherical charges are placed along with it. The lid of the drum is closed. 4. The drum is set to 500 rpms, then the sound proofing cabinet is closed and test is initiated. 5. When due rounds are done the fragmented sample is acquired from the drum and then sieved from sieve of 1.

6 mm and the retained material is weighted. 6. Lastly the Los Angeles test Value is acquired through the following formula Los Angeles Value = L.A Value = x 100 Where FW= Final Weight retained on 1.6mm Sieve Data and Calculations Type of Aggregate = Recycled Aggregate Initial mass of the sample = 5000 g Final mass of the sample retained = 3778.39 g On 1.6 mm sieve Los Angeles Value = L.A Value = x 100 Where FW= Final Weight retained on 1.6mm Sieve L.A Value = x 100 = 24.43 % Type of Aggregate = Thames Valley (Natural Aggregate) Initial mass of the sample = 5000 g Final mass of the sample retained = 4100 g On 1.

6 mm sieve Los Angeles Value = L.A Value = x 100 Where FW= Final Weight retained on 1.6mm Sieve L.A Value = x 100 = 18 % Discussion (a) Sources of Error There are several points during this experiment where that might cause an error in the test results.The first point which can be a source of error is the faulty preparation of standardized test specimen for testing, and the standards are not followed. Hence it is suggested that all specifications must be followed and exact percentages of aggregates are to be used.

So that the test results can be corrected and recommendations validated.Then the no of rpm must be 500 and the no of charges must be exactly 11. Then the material must be properly handled and after fragmentation process it should be ensured that the all the sample is taken from the drum and sieved properly. Then throughout the sieving process the sieves should be proper that is the aperture size should be uniform throughout the sieve. Old and over used sieves might have larger openings in them, hence contaminating the standard samples. b) The above table is an