This standard prescribes the methods of test for estimating deleterious materials and organic impurities in aggregates intended for use in concrete. It includes procedures for determining the percentage of clay, fine silt, dust, lightweight pieces, and the presence of harmful organic compounds that can inhibit cement hydration.
Specifies methods for determining the amount of deleterious materials and organic impurities in aggregates.
Quick Reference Values
NaOH solution concentration (Organic Impurities)3 percent
Observation duration (Organic Impurities)24 hours
Specific gravity of zinc chloride (Light-weight Pieces)2.0
Oven drying temperature100 to 110 °C
Volume of glass bottle for organic impurities test350 ml
Key Formulas
Percentage of clay, fine silt and fine dust = (Weight of fine material / Total weight of sample) x 100
Percentage of light-weight pieces = (Weight of decanted light pieces / Weight of test sample) x 100
Practical Notes
The colorimetric test for organic impurities is an indicator; if the liquid turns darker than the standard reference color, the aggregate should not be immediately rejected but subjected to mortar compressive strength tests.
The sedimentation method is the standard laboratory method and provides a more accurate determination of clay and fine silt compared to the rapid field decantation method.
When testing for lightweight pieces, the zinc chloride solution must be handled with care and its specific gravity strictly maintained at 2.0.