DELETERIOUS MATERIAL TEST OF AGGREGATE

Method of Deleterious material test of aggregate by routine examination.

Deleterious materials mean aggregate properties that can cause of effect on the strength and durability of the concrete. Impurities in Aggregates (soft particles, chert, clay lumps and coal, lignite, or other lightweight materials) are change the setting times and rates of hardening of concrete.

Test standard: IS 2386-Part II: 1963

Test Apparatus:

  • Weighing Balance
  • IS Sieves of size 40mm, 20mm, 10mm, 4.75mm, 2.36mm, 1.18mm, 850 microns
  • Hot air Oven.
  • GI tray

Sample preparation:

Dry the sample in hot air electric oven at a temperature not exceeding 110 °C.

Test sample from the representative sample shall be taken as:

  • For fine aggregate: The test sample shall consist of particle retained on 1.18mm IS Sieve & weight not less than 100gms.
  • For coarse aggregate: Test sample shall be prepared by sieving the material on different size IS sieves.

Weight of the sample for different sizes shall not be less than those given below:

Size of the particle Minimum weight of sample (gms)
Over 4.75 to 10mm1000
Over 10 to 20mm2000
Over 20 to 40mm3000
Over 40mm5000
Weight of the sample for different sizes

Test Procedure Deleterious material test of aggregate

Take sample by quartering method and Weight (say W1gms) & spread it on GI tray in thin layer.

Examine the test sample for clay lumps, which shall consist of all particles that can be easily broken into finely divided particles with the fingers.

After all clay particles have been broken, the residue from the clay lumps shall be removed using sieves as:

Size of particle (mm)Size of the sieve for sieving residue of clay lumps (mm)
Fine aggregate (Retained on 1.18mm IS Sieve)850 Microns
Over 4.75 to 10mm2.36
Over 10 to 20mm4.75
Over 20 to 40mm4.75
Over 40mm4.75
Size of sieve according to size of particle

Weight the sample again after removal of residue (Say W2, gms).

Calculated of Clay lumps (%) = {(W1-W2)/W1}x100

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Founder & Admin of civilengineeringsolution.com, I am a civil engineer working as a Assistant Engineer (QA/QC).

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