For determination of flakiness index of coarse aggregate, where the  size of the coarse aggregate are larger than 6.3mm . 

Reference Standards

IS : 2386 (Part I) – 1963 – Method of test for aggregates for concrete (Part I) Particle size and shape.

Equipment & Apparatus

  • Thickness gauge
  • Sieves [63, 50, 40, 31.5, 25, 20, 16, 12.5, 10 & 6.3mm]
  • Balance [0-10 kg]

    Thickness Gauge
    Thickness Gauge

Preparation sample

Surface dry samples is used for the test. A minimum number of 200 pieces of any specified fraction is required to do the test. 


  1. The sample is sieved through IS sieve specified in Table shown below.

    Dimension of Thickness and Length Gauge
    Dimension of Thickness and Length Gauge
  2. A minimum of 200 pieces of each fraction is taken and weighed.
  3. In order to separate flaky materials, each fraction is then gauged individually for thickness on a thickness gauge. 
  4. The total amount of flaky material passing the thickness gauge is weighed to an accuracy of 0.1% of the weight of sample. 


In order to calculate the flakiness index of the entire sample of aggregates, first the weight of each fraction of aggregate passing and retained on the specified set of sieves is noted (Y1, Y2, Y3, Y4…..etc). Each piece of these are tried to be passed through the slot of the specified thickness of the thickness gauge are found and weighed (y1, y2, y3, y4…etc). Then the flakiness index is the percentage of materials passed through the thickness gauge on the various thickness gauges, expressed as a percentage of the total weight of the sample gauged.

Aggregate flakiness index 1


Flakiness index is reported in percentage to the nearest whole number

Safety & Precautions

  • Use hand gloves while removing containers from oven after switching off the oven.
  • Use safety shoes, mask & aprons at the time of test.
  • Thoroughly clean & dry the container 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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