Elongation Index Test 1q495l

Transportation Engineering Laboratory, IITG

EXPERIMENT NO. NAME OF THE EXPERIMENT: ELONGATION INDEX TEST AIM OF THE EXPERIMENT: To determine the Elongation Index of the given sample of coarse aggregate. TEST DESCRIPTION: In order to calculate the elongation index of the entire sample of aggregates, first the weight of each fraction of aggregate ing and retained on the specified set of sieves is noted. Each piece of these are tried to be ed through specified length of the gauge length with its longest side and those elongated pieces which do not the gauge are separated and then the elongated index is the total weight of the material retained on the various length gauges, expressed as a percentage of the total weight of the sample gauged. APPARATUS REQUIRED FOR THE TEST: 

A balance which is having accuracy in measuring of 0.1% of the

 

weight of the sample. Metal Gauge: The metal gauge shall be of the pattern shown in Fig.1 Sieves: IS Sieves of sizes 25 mm, 20 mm, 16 mm, 12.5 mm, 10 mm and 6.3 mm.

Fig.1: Length gauge sketch

Fig.2:

Length

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Transportation Engineering Laboratory, IITG

RELEVANT CODES: ASTM 4791-10: Standard Test Method for Flat Particles, Elongated Particles or Flat and Elongated Particles in Coarse Aggregate, American Society for Testing and Materials IS 2386 (Part I)-1963 Methods of Test for aggregates for Concrete; Particle size and shape; Bureau of Indian Standards PROCEDURE: 1. The sample of aggregates to be tested is sieved through a set of sieves and separated into specified size ranges. 2. Minimum 200 pieces of any fraction to be tested are taken and weighed properly. 3. The aggregates from each of the size range are then individually ed through the appropriate gauge of the length gauge with the longest side in order to separate the elongated particles. 4. The gauge length will be 1.8 times the main size of the aggregate. 5. The portion of elongated aggregate having length greater than the specified gauge from each range is weighed. 6. This weight is then divided by the total weight of sample taken from different size ranges and the ratio is expressed in percentage which is the required elongation index.

PRECAUTIONS:  Use safety shoes, mask & aprons at the time of test.  Thoroughly clean & dry the gauge before testing.  Special care should be taken that no outer air enters when using the balance.  All parts of the equipment should always be kept clean.  After the end of the test sieve should be clean by smooth brush.

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