specific gravity and water absorption of coarse aggregate

Method of specific gravity and water absorption of coarse aggregate using Glass vessel

Specific gravity test of aggregates is done to measure the quality of the aggregates and the water absorption test determines the water holding capacity of the coarse and fine aggregates. Method of specific gravity and water absorption of coarse aggregate given below:

Test standard : IS 2386 -Part 3 : 1963

Test Apparatus :

  1. Weighing Balance
  2. Wide-mouthed glass vessel or Jar of capacity about 1.5 liters
  3. Plane glass plate
  4. Hot air oven
  5. Airtight container
  6. Dry soft absorbent cloths.

Test Procedure :

  1. Take about 1kg of the sample by quartering method, washed and remove all fine particles and dust.
  2. Fill the aggregate in glass vessel & immersed it in distilled water at a temperature of 22-32 °C for 24±1/2 hours.
  3. After that, it has to rotate vessel clockwise & anti-clockwise for removing the air and bubbles on the surface.
  4. Now overfilled glass vessel by adding distilled water & slide the plane disc of glass plate over the vessel so that no air is entrapped in the vessel.
  5. Weight the vessel (A, gms), The vessel shall be dried on outside.
  6. Empty the vessel, Refill the vessel with distilled water & slide the glass plate. Dry the vessel from outside & again weighed (B, gms).
  7. Dry the sample using dry soft cloths gently (Saturated Condition ) and aggregate shall be weighed ( C, gms)
  8. Now aggregate sample shall be placed in the oven at a temperature of 100-1100C for 24±1/2 hours.
  9. After 24 hour again weighed the sample aggregate (D, gms).

Calculation of Specific gravity & water absorption of the aggregate

Specific gravity = {D/[C-(A-B)]}

Apparent specific gravity = {D/[D-(A-B)]}

Water absorption (%) = {(C-D)/D} x 100

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